diff --git a/compiler/.vscode/settings.json b/compiler/.vscode/settings.json
index 956857a..0da43e9 100644
--- a/compiler/.vscode/settings.json
+++ b/compiler/.vscode/settings.json
@@ -1,7 +1,7 @@
 {
   "C_Cpp.default.includePath": [
     "${workspaceFolder}/include/",
-    "/usr/include/antlr4-runtime",
+    "${workspaceFolder}/build/antlr4_runtime/src/antlr4_runtime/runtime/Cpp/runtime/src",
   ],
   "files.associations": {
     "*.embeddedhtml": "html",
@@ -77,6 +77,8 @@
     "typeinfo": "cpp",
     "valarray": "cpp",
     "variant": "cpp",
-    "*.inc": "cpp"
+    "*.inc": "cpp",
+    "source_location": "cpp",
+    "text_encoding": "cpp"
   }
 }
\ No newline at end of file
diff --git a/compiler/CMakeLists.txt b/compiler/CMakeLists.txt
index f79d0b2..7f5ab21 100644
--- a/compiler/CMakeLists.txt
+++ b/compiler/CMakeLists.txt
@@ -17,7 +17,7 @@ list(APPEND CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake)
 include(ExternalAntlr4Cpp)
 
 find_package( 
- Boost 1.84 REQUIRED 
+ Boost 1.83 REQUIRED 
  COMPONENTS json 
 )
 
diff --git a/compiler/cmake/ExternalAntlr4Cpp.cmake b/compiler/cmake/ExternalAntlr4Cpp.cmake
index 4da7fbc..95953e1 100644
--- a/compiler/cmake/ExternalAntlr4Cpp.cmake
+++ b/compiler/cmake/ExternalAntlr4Cpp.cmake
@@ -18,7 +18,7 @@ endif()
 
 # Ensure that the include dir already exists at configure time (to avoid cmake erroring
 # on non-existent include dirs)
-file(MAKE_DIRECTORY "${ANTLR4_INCLUDE_DIRS}")
+file(MAKE_DIRECTORY ${ANTLR4_INCLUDE_DIRS})
 
 if(${CMAKE_GENERATOR} MATCHES "Visual Studio.*")
   set(ANTLR4_OUTPUT_DIR ${ANTLR4_ROOT}/runtime/Cpp/runtime/$(Configuration))
diff --git a/compiler/include/AST/AST.h b/compiler/include/AST/AST.h
new file mode 100644
index 0000000..bc6f373
--- /dev/null
+++ b/compiler/include/AST/AST.h
@@ -0,0 +1,27 @@
+#pragma once
+
+#include "Base.h"
+
+#include "Expr/BinExpr.h"
+#include "Expr/CallExpr.h"
+#include "Expr/CastExpr.h"
+#include "Expr/Identifier.h"
+#include "Expr/LambdaExpr.h"
+#include "Expr/UnExpr.h"
+#include "Expr/Value.h"
+
+#include "Module/Import.h"
+#include "Module/Module.h"
+
+#include "Stmt/AssignStmt.h"
+#include "Stmt/ExprStmt.h"
+#include "Stmt/FnDecl.h"
+#include "Stmt/IfStmt.h"
+#include "Stmt/RetStmt.h"
+#include "Stmt/VarDecl.h"
+#include "Stmt/WhileStmt.h"
+
+#include "Type/FunctionType.h"
+#include "Type/PrimitiveType.h"
+
+#include "TypeName/PrimitiveTypeName.h"
diff --git a/compiler/include/AST/Base.h b/compiler/include/AST/Base.h
index 5943484..209c28c 100644
--- a/compiler/include/AST/Base.h
+++ b/compiler/include/AST/Base.h
@@ -1,5 +1,6 @@
 #pragma once
 
+#include <any>
 #include <boost/json/serialize.hpp>
 #include <exception>
 #include <functional>
@@ -11,42 +12,75 @@
 
 #include <boost/json.hpp>
 
-#define LOC_ARG const Location &location
+#define LOC_ARG const SourceRange &sourceRange
 
 namespace plsm {
 namespace ast {
 
-class Location {
+class BinExpr;
+class CallExpr;
+class CastExpr;
+class Identifier;
+class LambdaExpr;
+class UnExpr;
+class IntValue;
+class FloatValue;
+
+class Import;
+class Module;
+
+class AssignStmt;
+class ExprStmt;
+class FnParam;
+class FnDecl;
+class IfStmt;
+class RetStmt;
+class VarDecl;
+class WhileStmt;
+
+class PrimitiveTypeName;
+
+class ASTVisitor {
 public:
-  Location(const std::string &file, std::pair<size_t, size_t> start,
-           std::pair<size_t, size_t> end)
-      : file(file), start(start), end(end) {}
+  virtual ~ASTVisitor() = default;
 
-  const std::string file;
-  const std::pair<size_t, size_t> start, end;
+  virtual std::any visit(BinExpr &binExpr, std::any param) = 0;
+  virtual std::any visit(CallExpr &callExpr, std::any param) = 0;
+  virtual std::any visit(CastExpr &castExpr, std::any param) = 0;
+  virtual std::any visit(Identifier &identifier, std::any param) = 0;
+  virtual std::any visit(LambdaExpr &lambdaExpr, std::any param) = 0;
+  virtual std::any visit(UnExpr &unExpr, std::any param) = 0;
+  virtual std::any visit(IntValue &intValue, std::any param) = 0;
+  virtual std::any visit(FloatValue &floatValue, std::any param) = 0;
 
-  static Location json() { return Location("<json>", {-1, -1}, {-1, -1}); };
+  virtual std::any visit(Import &import, std::any param) = 0;
+  virtual std::any visit(Module &module, std::any param) = 0;
+
+  virtual std::any visit(AssignStmt &assignStmt, std::any param) = 0;
+  virtual std::any visit(ExprStmt &exprStmt, std::any param) = 0;
+  virtual std::any visit(FnParam &fnParam, std::any param) = 0;
+  virtual std::any visit(FnDecl &fnDecl, std::any param) = 0;
+  virtual std::any visit(IfStmt &ifStmt, std::any param) = 0;
+  virtual std::any visit(RetStmt &retStmt, std::any param) = 0;
+  virtual std::any visit(VarDecl &varDecl, std::any param) = 0;
+  virtual std::any visit(WhileStmt &whileStmt, std::any param) = 0;
+
+  virtual std::any visit(PrimitiveTypeName &primitiveTypeName,
+                         std::any param) = 0;
 };
 
-class ASTNode {
-public:
-  ASTNode(LOC_ARG) : location(location) {}
-  virtual ~ASTNode() = default;
+} // namespace ast
+} // namespace plsm
 
-  const Location location;
+namespace plsm {
+namespace ast {
+
+class Jsonable {
+public:
+  virtual ~Jsonable() = default;
 
   virtual boost::json::value toJson() = 0;
 
-  virtual std::string toJsonString() {
-    return boost::json::serialize(toJson());
-  }
-
-  static std::unique_ptr<ASTNode> fromJson(boost::json::value json);
-
-  virtual bool isExpr() { return false; }
-  virtual bool isStmt() { return false; }
-  virtual bool isType() { return false; }
-
 protected:
   template <class CurrNode>
   static inline boost::json::value getJsonProperty(boost::json::value json,
@@ -88,7 +122,7 @@ protected:
                                     std::string property) {
     auto arr = getJsonProperty<CurrNode>(json, property).as_array();
 
-    std::vector<std::unique_ptr<SubNode>> result;
+    std::vector<SubNode *> result;
     for (auto &el : arr) {
       result.push_back(SubNode::fromJson(el));
     }
@@ -97,31 +131,80 @@ protected:
   }
 };
 
+class SourceRange {
+public:
+  SourceRange(const std::string &file, const std::string &text,
+              std::pair<size_t, size_t> start, std::pair<size_t, size_t> end)
+      : file(file), text(text), start(start), end(end) {}
+
+  const std::string file, text;
+  const std::pair<size_t, size_t> start, end;
+
+  static SourceRange unknown() {
+    return SourceRange("<?>", "<?>", {-1, -1}, {-1, -1});
+  };
+
+  static SourceRange json() {
+    return SourceRange("<json>", "<?>", {-1, -1}, {-1, -1});
+  };
+};
+
+class ASTNode : public Jsonable {
+public:
+  ASTNode(LOC_ARG) : Jsonable(), sourceRange(sourceRange) {}
+  virtual ~ASTNode() = default;
+
+  const SourceRange sourceRange;
+
+  virtual std::string toJsonString() {
+    return boost::json::serialize(toJson(), {});
+  }
+
+  static ASTNode *fromJson(boost::json::value json);
+
+  virtual bool isExpr() { return false; }
+  virtual bool isStmt() { return false; }
+  virtual bool isTypeName() { return false; }
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) = 0;
+};
+
 class Expr : public ASTNode {
 public:
-  Expr(LOC_ARG) : ASTNode(location) {}
+  Expr(LOC_ARG) : ASTNode(sourceRange) {}
+  virtual ~Expr() = default;
 
-  static std::unique_ptr<Expr> fromJson(boost::json::value json);
+  static Expr *fromJson(boost::json::value json);
 
   virtual bool isExpr() override { return true; }
 };
 
 class Stmt : public ASTNode {
 public:
-  Stmt(LOC_ARG) : ASTNode(location) {}
+  Stmt(LOC_ARG) : ASTNode(sourceRange) {}
+  virtual ~Stmt() = default;
 
-  static std::unique_ptr<Stmt> fromJson(boost::json::value json);
+  static Stmt *fromJson(boost::json::value json);
 
   virtual bool isStmt() override { return true; }
 };
 
-class Type : public ASTNode {
+class TypeName : public ASTNode {
 public:
-  Type(LOC_ARG) : ASTNode(location) {}
+  TypeName(LOC_ARG) : ASTNode(sourceRange) {}
+  virtual ~TypeName() = default;
 
-  static std::unique_ptr<Type> fromJson(boost::json::value json);
+  static TypeName *fromJson(boost::json::value json);
 
-  virtual bool isType() override { return true; }
+  virtual bool isTypeName() override { return true; }
+};
+
+class Type : public Jsonable {
+public:
+  Type() : Jsonable() {}
+  virtual ~Type() = default;
+
+  static Type *fromJson(boost::json::value json);
 };
 
 } // namespace ast
diff --git a/compiler/include/AST/Def.h b/compiler/include/AST/Def.h
deleted file mode 100644
index c0e2da4..0000000
--- a/compiler/include/AST/Def.h
+++ /dev/null
@@ -1,29 +0,0 @@
-#pragma once
-
-#include "Base.h"
-
-#include "Expr/BinExpr.h"
-#include "Expr/Block.h"
-#include "Expr/Call.h"
-#include "Expr/Closure.h"
-#include "Expr/Identifier.h"
-#include "Expr/PropExpr.h"
-#include "Expr/Tuple.h"
-#include "Expr/UnaryExpr.h"
-#include "Expr/Value.h"
-
-#include "Stmt/ExprStmt.h"
-#include "Stmt/FnDef.h"
-#include "Stmt/TraitAlias.h"
-#include "Stmt/TraitDef.h"
-#include "Stmt/TypeAlias.h"
-#include "Stmt/TypeDef.h"
-#include "Stmt/ValDecl.h"
-
-#include "Type/Closure.h"
-#include "Type/Generic.h"
-#include "Type/Named.h"
-#include "Type/Tuple.h"
-
-#include "Module/Import.h"
-#include "Module/Module.h"
diff --git a/compiler/include/AST/Expr/BinExpr.h b/compiler/include/AST/Expr/BinExpr.h
index bb5fb93..5a36d08 100644
--- a/compiler/include/AST/Expr/BinExpr.h
+++ b/compiler/include/AST/Expr/BinExpr.h
@@ -1,37 +1,44 @@
 #pragma once
 
 #include "AST/Base.h"
-#include <iomanip>
 #include <memory>
-#include <sstream>
 #include <string>
 
 namespace plsm {
 namespace ast {
 
-class BinExpr : public Expr {
-  const std::string op;
-  const std::unique_ptr<Expr> left, right;
+enum BinOp {
+  ADD,
+  SUB,
+  MUL,
+  DIV,
+  MOD,
 
-public:
-  BinExpr(LOC_ARG, std::unique_ptr<Expr> &left, const std::string &op,
-          std::unique_ptr<Expr> &right)
-      : Expr(location), left(std::move(left)), op(op), right(std::move(right)) {
-  }
+  EQ,
+  NE,
+  GT,
+  GE,
+  LT,
+  LE,
 
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<BinExpr> fromJson(boost::json::value json);
+  AND,
+  OR,
 };
 
-class PrefExpr : public Expr {
-  const std::unique_ptr<Expr> expr;
+class BinExpr : public Expr {
+  const BinOp op;
+  const std::shared_ptr<Expr> lhs, rhs;
 
 public:
-  PrefExpr(LOC_ARG, std::unique_ptr<Expr> &expr)
-      : Expr(location), expr(std::move(expr)) {}
+  BinExpr(LOC_ARG, const BinOp op, Expr *lhs, Expr *rhs)
+      : Expr(sourceRange), op(op), lhs(lhs), rhs(rhs) {}
 
   virtual boost::json::value toJson() override;
-  static std::unique_ptr<PrefExpr> fromJson(boost::json::value json);
+  static BinExpr *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
 };
 
 } // namespace ast
diff --git a/compiler/include/AST/Expr/Block.h b/compiler/include/AST/Expr/Block.h
deleted file mode 100644
index 7b7843c..0000000
--- a/compiler/include/AST/Expr/Block.h
+++ /dev/null
@@ -1,25 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <memory>
-#include <sstream>
-#include <vector>
-
-namespace plsm {
-namespace ast {
-
-class BlockExpr : public Expr {
-  const std::vector<std::unique_ptr<Stmt>> stmts;
-  const std::unique_ptr<Expr> result;
-
-public:
-  BlockExpr(LOC_ARG, std::vector<std::unique_ptr<Stmt>> &stmts,
-            std::unique_ptr<Expr> &result)
-      : Expr(location), stmts(std::move(stmts)), result(std::move(result)) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<BlockExpr> fromJson(boost::json::value json);
-};
-
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Expr/Call.h b/compiler/include/AST/Expr/Call.h
deleted file mode 100644
index e7d8dbe..0000000
--- a/compiler/include/AST/Expr/Call.h
+++ /dev/null
@@ -1,25 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <memory>
-#include <sstream>
-#include <vector>
-
-namespace plsm {
-namespace ast {
-
-class CallExpr : public Expr {
-  const std::unique_ptr<Expr> callee;
-  const std::vector<std::unique_ptr<Expr>> args;
-
-public:
-  CallExpr(LOC_ARG, std::unique_ptr<Expr> &callee,
-           std::vector<std::unique_ptr<Expr>> &args)
-      : Expr(location), callee(std::move(callee)), args(std::move(args)) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<CallExpr> fromJson(boost::json::value json);
-};
-
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Expr/CallExpr.h b/compiler/include/AST/Expr/CallExpr.h
new file mode 100644
index 0000000..5dbdd5a
--- /dev/null
+++ b/compiler/include/AST/Expr/CallExpr.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <memory>
+#include <vector>
+
+namespace plsm {
+namespace ast {
+
+class CallExpr : public Expr {
+  const std::shared_ptr<Expr> callee;
+  std::vector<std::shared_ptr<Expr>> args;
+
+public:
+  CallExpr(LOC_ARG, Expr *callee, std::vector<Expr *> args)
+      : Expr(sourceRange), callee(callee), args() {
+    for (auto &arg : args) {
+      this->args.push_back(std::shared_ptr<Expr>(arg));
+    }
+  }
+
+  virtual boost::json::value toJson() override;
+  static CallExpr *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
+};
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/include/AST/Expr/CastExpr.h b/compiler/include/AST/Expr/CastExpr.h
new file mode 100644
index 0000000..d4224ad
--- /dev/null
+++ b/compiler/include/AST/Expr/CastExpr.h
@@ -0,0 +1,26 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <string>
+
+namespace plsm {
+namespace ast {
+
+class CastExpr : public Expr {
+  const std::shared_ptr<Expr> value;
+  const std::shared_ptr<TypeName> typeName;
+
+public:
+  CastExpr(LOC_ARG, Expr *value, TypeName *typeName)
+      : Expr(sourceRange), value(value), typeName(typeName) {}
+
+  virtual boost::json::value toJson() override;
+  static CastExpr *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
+};
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/include/AST/Expr/Closure.h b/compiler/include/AST/Expr/Closure.h
deleted file mode 100644
index a04e720..0000000
--- a/compiler/include/AST/Expr/Closure.h
+++ /dev/null
@@ -1,25 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <memory>
-#include <sstream>
-#include <string>
-#include <vector>
-
-namespace plsm {
-namespace ast {
-class FnArg;
-
-class Closure : public Expr {
-  const std::vector<std::unique_ptr<FnArg>> args;
-  const std::unique_ptr<Expr> body;
-
-public:
-  Closure(LOC_ARG, std::vector<std::unique_ptr<FnArg>> &args, std::unique_ptr<Expr> &body)
-      : Expr(location), args(std::move(args)), body(std::move(body)) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<Closure> fromJson(boost::json::value json);
-};
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Expr/Identifier.h b/compiler/include/AST/Expr/Identifier.h
index 384b32e..451c300 100644
--- a/compiler/include/AST/Expr/Identifier.h
+++ b/compiler/include/AST/Expr/Identifier.h
@@ -9,10 +9,15 @@ class Identifier : public Expr {
   const std::string name;
 
 public:
-  Identifier(LOC_ARG, const std::string &name) : Expr(location), name(name) {}
+  Identifier(LOC_ARG, const std::string &name)
+      : Expr(sourceRange), name(name) {}
 
   virtual boost::json::value toJson() override;
-  static std::unique_ptr<Identifier> fromJson(boost::json::value json);
+  static Identifier *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
 };
 
 } // namespace ast
diff --git a/compiler/include/AST/Expr/LambdaExpr.h b/compiler/include/AST/Expr/LambdaExpr.h
new file mode 100644
index 0000000..3d94e95
--- /dev/null
+++ b/compiler/include/AST/Expr/LambdaExpr.h
@@ -0,0 +1,36 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <memory>
+#include <string>
+#include <vector>
+
+namespace plsm {
+namespace ast {
+class FnParam;
+
+class LambdaExpr : public Expr {
+  std::vector<std::shared_ptr<FnParam>> params;
+  std::vector<std::shared_ptr<Expr>> body;
+
+public:
+  LambdaExpr(LOC_ARG, std::vector<FnParam *> params, std::vector<Expr *> body)
+      : Expr(sourceRange), params(), body() {
+    for (auto &param : params) {
+      this->params.push_back(std::shared_ptr<FnParam>(param));
+    }
+
+    for (auto &expr : body) {
+      this->body.push_back(std::shared_ptr<Expr>(expr));
+    }
+  }
+
+  virtual boost::json::value toJson() override;
+  static LambdaExpr *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
+};
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/include/AST/Expr/PropExpr.h b/compiler/include/AST/Expr/PropExpr.h
deleted file mode 100644
index 564c826..0000000
--- a/compiler/include/AST/Expr/PropExpr.h
+++ /dev/null
@@ -1,22 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <memory>
-#include <sstream>
-#include <string>
-
-namespace plsm {
-namespace ast {
-class PropExpr : public Expr {
-  const std::unique_ptr<Expr> expr;
-  const std::string property;
-
-public:
-  PropExpr(LOC_ARG, std::unique_ptr<Expr> &expr, const std::string &property)
-      : Expr(location), expr(std::move(expr)), property(property) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<PropExpr> fromJson(boost::json::value json);
-};
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Expr/Tuple.h b/compiler/include/AST/Expr/Tuple.h
deleted file mode 100644
index db45bf2..0000000
--- a/compiler/include/AST/Expr/Tuple.h
+++ /dev/null
@@ -1,23 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <memory>
-#include <sstream>
-#include <vector>
-
-namespace plsm {
-namespace ast {
-
-class Tuple : public Expr {
-  const std::vector<std::unique_ptr<Expr>> values;
-
-public:
-  Tuple(LOC_ARG, std::vector<std::unique_ptr<Expr>> &values)
-      : Expr(location), values(std::move(values)) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<Tuple> fromJson(boost::json::value json);
-};
-
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Expr/UnExpr.h b/compiler/include/AST/Expr/UnExpr.h
new file mode 100644
index 0000000..a415435
--- /dev/null
+++ b/compiler/include/AST/Expr/UnExpr.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <memory>
+#include <string>
+
+namespace plsm {
+namespace ast {
+enum UnOp {
+  NOT,
+  POS,
+  NEG,
+};
+
+class UnExpr : public Expr {
+  const UnOp op;
+  const std::shared_ptr<Expr> expr;
+
+public:
+  UnExpr(LOC_ARG, const UnOp op, Expr *expr)
+      : Expr(sourceRange), op(op), expr(expr) {}
+
+  virtual boost::json::value toJson() override;
+  static UnExpr *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
+};
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/include/AST/Expr/UnaryExpr.h b/compiler/include/AST/Expr/UnaryExpr.h
deleted file mode 100644
index 1809242..0000000
--- a/compiler/include/AST/Expr/UnaryExpr.h
+++ /dev/null
@@ -1,23 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <iomanip>
-#include <memory>
-#include <sstream>
-#include <string>
-
-namespace plsm {
-namespace ast {
-class UnaryExpr : public Expr {
-  const std::string op;
-  const std::unique_ptr<Expr> expr;
-
-public:
-  UnaryExpr(LOC_ARG, const std::string &op, std::unique_ptr<Expr> &expr)
-      : Expr(location), op(op), expr(std::move(expr)) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<UnaryExpr> fromJson(boost::json::value json);
-};
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Expr/Value.h b/compiler/include/AST/Expr/Value.h
index 32c730c..81f4b8a 100644
--- a/compiler/include/AST/Expr/Value.h
+++ b/compiler/include/AST/Expr/Value.h
@@ -1,38 +1,47 @@
 #pragma once
 
 #include "AST/Base.h"
-#include <string>
-#include <cstdint>
 #include <cfloat>
+#include <cstdint>
+#include <string>
 
 namespace plsm {
 namespace ast {
-class NullValue : public Expr {
-public:
-  NullValue(LOC_ARG) : Expr(location) {}
+// class NullValue : public Expr {
+// public:
+//   NullValue(LOC_ARG) : Expr(sourceRange) {}
 
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<NullValue> fromJson(boost::json::value json);
-};
+//   virtual boost::json::value toJson() override;
+//   static std::unique_ptr<NullValue> fromJson(boost::json::value json);
+// };
 
 class IntValue : public Expr {
   const std::int64_t value;
 
 public:
-  IntValue(LOC_ARG, int64_t value) : Expr(location), value(value) {}
+  IntValue(LOC_ARG, int64_t value) : Expr(sourceRange), value(value) {}
 
   virtual boost::json::value toJson() override;
-  static std::unique_ptr<IntValue> fromJson(boost::json::value json);
+  static IntValue *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
 };
 
 class FloatValue : public Expr {
   const std::double_t value;
 
 public:
-  FloatValue(LOC_ARG, double value) : Expr(location), value(value) {}
+  FloatValue(LOC_ARG, double value) : Expr(sourceRange), value(value) {}
 
   virtual boost::json::value toJson() override;
-  static std::unique_ptr<FloatValue> fromJson(boost::json::value json);
+  static FloatValue *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
 };
+
 } // namespace ast
 } // namespace plsm
diff --git a/compiler/include/AST/Module/Import.h b/compiler/include/AST/Module/Import.h
index c0b8038..6ba9014 100644
--- a/compiler/include/AST/Module/Import.h
+++ b/compiler/include/AST/Module/Import.h
@@ -1,8 +1,6 @@
 #pragma once
 
 #include "AST/Base.h"
-#include <iomanip>
-#include <sstream>
 #include <string>
 
 namespace plsm {
@@ -12,10 +10,14 @@ class Import : public ASTNode {
 
 public:
   Import(LOC_ARG, const std::string &moduleName)
-      : ASTNode(location), moduleName(moduleName) {}
+      : ASTNode(sourceRange), moduleName(moduleName) {}
 
   virtual boost::json::value toJson() override;
-  static std::unique_ptr<Import> fromJson(boost::json::value json);
+  static Import *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
 };
 } // namespace ast
 } // namespace plsm
diff --git a/compiler/include/AST/Module/Module.h b/compiler/include/AST/Module/Module.h
index 84140c2..c2fd40e 100644
--- a/compiler/include/AST/Module/Module.h
+++ b/compiler/include/AST/Module/Module.h
@@ -1,11 +1,8 @@
 #pragma once
 
 #include "AST/Base.h"
-#include <cstddef>
-#include <iomanip>
 #include <memory>
 #include <vector>
-#include <sstream>
 
 namespace plsm {
 namespace ast {
@@ -13,18 +10,28 @@ class Import;
 
 class Module : public ASTNode {
   const std::string name;
-  const std::vector<std::unique_ptr<Import>> imports;
-  const std::vector<std::unique_ptr<Stmt>> stmts;
+  std::vector<std::shared_ptr<Import>> imports;
+  std::vector<std::shared_ptr<Stmt>> stmts;
 
 public:
-  Module(LOC_ARG, const std::string &name,
-         std::vector<std::unique_ptr<Import>> &imports,
-         std::vector<std::unique_ptr<Stmt>> &stmts)
-      : ASTNode(location), name(name), imports(std::move(imports)),
-        stmts(std::move(stmts)) {}
+  Module(LOC_ARG, const std::string &name, const std::vector<Import *> &imports,
+         const std::vector<Stmt *> &stmts)
+      : ASTNode(sourceRange), name(name), imports(), stmts() {
+    for (auto &import : imports) {
+      this->imports.push_back(std::shared_ptr<Import>(import));
+    }
+
+    for (auto &stmt : stmts) {
+      this->stmts.push_back(std::shared_ptr<Stmt>(stmt));
+    }
+  }
 
   virtual boost::json::value toJson() override;
-  static std::unique_ptr<Module> fromJson(boost::json::value json);
+  static Module *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
 };
 } // namespace ast
 } // namespace plsm
diff --git a/compiler/include/AST/Stmt/AssignStmt.h b/compiler/include/AST/Stmt/AssignStmt.h
new file mode 100644
index 0000000..560145e
--- /dev/null
+++ b/compiler/include/AST/Stmt/AssignStmt.h
@@ -0,0 +1,27 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <memory>
+#include <string>
+
+namespace plsm {
+namespace ast {
+
+class AssignStmt : public Stmt {
+  const std::shared_ptr<Expr> lval;
+  const std::shared_ptr<Expr> rval;
+
+public:
+  AssignStmt(LOC_ARG, Expr *lval, Expr *rval)
+      : Stmt(sourceRange), lval(lval), rval(rval) {}
+
+  virtual boost::json::value toJson() override;
+  static AssignStmt *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
+};
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/include/AST/Stmt/ExprStmt.h b/compiler/include/AST/Stmt/ExprStmt.h
index 9ec58d8..6dfeb55 100644
--- a/compiler/include/AST/Stmt/ExprStmt.h
+++ b/compiler/include/AST/Stmt/ExprStmt.h
@@ -6,14 +6,17 @@
 namespace plsm {
 namespace ast {
 class ExprStmt : public Stmt {
-  const std::unique_ptr<Expr> expr;
+  const std::shared_ptr<Expr> expr;
 
 public:
-  ExprStmt(LOC_ARG, std::unique_ptr<Expr> &expr)
-      : Stmt(location), expr(std::move(expr)) {}
+  ExprStmt(LOC_ARG, Expr *expr) : Stmt(sourceRange), expr(expr) {}
 
   virtual boost::json::value toJson() override;
-  static std::unique_ptr<ExprStmt> fromJson(boost::json::value json);
+  static ExprStmt *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
 };
 } // namespace ast
 } // namespace plsm
diff --git a/compiler/include/AST/Stmt/FnDecl.h b/compiler/include/AST/Stmt/FnDecl.h
new file mode 100644
index 0000000..1ab6c43
--- /dev/null
+++ b/compiler/include/AST/Stmt/FnDecl.h
@@ -0,0 +1,56 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <memory>
+#include <string>
+#include <vector>
+
+namespace plsm {
+namespace ast {
+
+class FnParam : public ASTNode {
+  const std::string name;
+  const std::shared_ptr<TypeName> typeName;
+
+public:
+  FnParam(LOC_ARG, const std::string &name, TypeName *typeName)
+      : ASTNode(sourceRange), name(name), typeName(typeName) {}
+
+  virtual boost::json::value toJson() override;
+  static FnParam *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
+};
+
+class FnDecl : public Stmt {
+  const std::string name;
+  std::vector<std::shared_ptr<FnParam>> params;
+  const std::shared_ptr<TypeName> returnTypeName;
+  std::vector<std::shared_ptr<Stmt>> body;
+
+public:
+  FnDecl(LOC_ARG, const std::string &name, const std::vector<FnParam *> &params,
+         TypeName *returnTypeName, const std::vector<Stmt *> &body)
+      : Stmt(sourceRange), name(name), params(), returnTypeName(returnTypeName),
+        body() {
+    for (auto &param : params) {
+      this->params.push_back(std::shared_ptr<FnParam>(param));
+    }
+
+    for (auto &stmt : body) {
+      this->body.push_back(std::shared_ptr<Stmt>(stmt));
+    }
+  }
+
+  virtual boost::json::value toJson() override;
+  static FnDecl *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
+};
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/include/AST/Stmt/FnDef.h b/compiler/include/AST/Stmt/FnDef.h
deleted file mode 100644
index 7d57ece..0000000
--- a/compiler/include/AST/Stmt/FnDef.h
+++ /dev/null
@@ -1,41 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <iomanip>
-#include <memory>
-#include <sstream>
-#include <string>
-#include <vector>
-
-namespace plsm {
-namespace ast {
-class FnArg : public ASTNode {
-  const std::string name;
-  const std::unique_ptr<Type> type;
-
-public:
-  FnArg(LOC_ARG, const std::string &name, std::unique_ptr<Type> &type)
-      : ASTNode(location), name(name), type(std::move(type)) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<FnArg> fromJson(boost::json::value json);
-};
-
-class FnDef : public Stmt {
-  const std::string name;
-  const std::vector<std::unique_ptr<FnArg>> args;
-  const std::unique_ptr<Type> returnType;
-  const std::unique_ptr<Expr> body;
-
-public:
-  FnDef(LOC_ARG, const std::string &name,
-        std::vector<std::unique_ptr<FnArg>> &args,
-        std::unique_ptr<Type> &returnType, std::unique_ptr<Expr> &body)
-      : Stmt(location), name(name), args(std::move(args)),
-        returnType(std::move(returnType)), body(std::move(body)) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<FnDef> fromJson(boost::json::value json);
-};
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Stmt/IfStmt.h b/compiler/include/AST/Stmt/IfStmt.h
new file mode 100644
index 0000000..f32400a
--- /dev/null
+++ b/compiler/include/AST/Stmt/IfStmt.h
@@ -0,0 +1,36 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <memory>
+#include <vector>
+
+namespace plsm {
+namespace ast {
+
+class IfStmt : public Stmt {
+  const std::shared_ptr<Expr> condition;
+  std::vector<std::shared_ptr<Stmt>> ifBody, elseBody;
+
+public:
+  IfStmt(LOC_ARG, Expr *condition, const std::vector<Stmt *> &ifBody,
+         const std::vector<Stmt *> &elseBody)
+      : Stmt(sourceRange), condition(condition) {
+    for (auto &stmt : ifBody) {
+      this->ifBody.push_back(std::shared_ptr<Stmt>(stmt));
+    }
+
+    for (auto &stmt : elseBody) {
+      this->elseBody.push_back(std::shared_ptr<Stmt>(stmt));
+    }
+  }
+
+  virtual boost::json::value toJson() override;
+  static IfStmt *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
+};
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/include/AST/Stmt/RetStmt.h b/compiler/include/AST/Stmt/RetStmt.h
new file mode 100644
index 0000000..b8514d5
--- /dev/null
+++ b/compiler/include/AST/Stmt/RetStmt.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <memory>
+
+namespace plsm {
+namespace ast {
+class RetStmt : public Stmt {
+  const std::shared_ptr<Expr> value;
+
+public:
+  RetStmt(LOC_ARG, Expr *value) : Stmt(sourceRange), value(value) {}
+
+  virtual boost::json::value toJson() override;
+  static RetStmt *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
+};
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/include/AST/Stmt/TraitAlias.h b/compiler/include/AST/Stmt/TraitAlias.h
deleted file mode 100644
index 9ad1723..0000000
--- a/compiler/include/AST/Stmt/TraitAlias.h
+++ /dev/null
@@ -1,24 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <iomanip>
-#include <memory>
-#include <sstream>
-#include <string>
-#include <vector>
-
-namespace plsm {
-namespace ast {
-class TraitAlias : public Stmt {
-  const std::string alias;
-  const std::string aliased;
-
-public:
-  TraitAlias(LOC_ARG, const std::string &alias, const std::string &aliased)
-      : Stmt(location), alias(alias), aliased(aliased) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<TraitAlias> fromJson(boost::json::value json);
-};
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Stmt/TraitDef.h b/compiler/include/AST/Stmt/TraitDef.h
deleted file mode 100644
index 946a055..0000000
--- a/compiler/include/AST/Stmt/TraitDef.h
+++ /dev/null
@@ -1,26 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <iomanip>
-#include <memory>
-#include <sstream>
-#include <string>
-#include <vector>
-
-namespace plsm {
-namespace ast {
-class FnDef;
-class TraitDef : public Stmt {
-  const std::string name;
-  const std::vector<std::unique_ptr<FnDef>> traits;
-
-public:
-  TraitDef(LOC_ARG, const std::string &name,
-           std::vector<std::unique_ptr<FnDef>> &traits)
-      : Stmt(location), name(name), traits(std::move(traits)) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<TraitDef> fromJson(boost::json::value json);
-};
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Stmt/TypeAlias.h b/compiler/include/AST/Stmt/TypeAlias.h
deleted file mode 100644
index 97a3060..0000000
--- a/compiler/include/AST/Stmt/TypeAlias.h
+++ /dev/null
@@ -1,24 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <iomanip>
-#include <memory>
-#include <sstream>
-#include <string>
-#include <vector>
-
-namespace plsm {
-namespace ast {
-class TypeAlias : public Stmt {
-  const std::string alias;
-  const std::unique_ptr<Type> type;
-
-public:
-  TypeAlias(LOC_ARG, const std::string &alias, std::unique_ptr<Type> &type)
-      : Stmt(location), alias(alias), type(std::move(type)) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<TypeAlias> fromJson(boost::json::value json);
-};
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Stmt/TypeDef.h b/compiler/include/AST/Stmt/TypeDef.h
deleted file mode 100644
index 883bd1c..0000000
--- a/compiler/include/AST/Stmt/TypeDef.h
+++ /dev/null
@@ -1,29 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <memory>
-#include <string>
-#include <vector>
-
-namespace plsm {
-namespace ast {
-class FnDef;
-class FnArg;
-
-class TypeDef : public Stmt {
-  const std::string name;
-  const std::vector<std::unique_ptr<FnArg>> attrs;
-  const std::vector<std::unique_ptr<FnDef>> members;
-
-public:
-  TypeDef(LOC_ARG, const std::string &name,
-          std::vector<std::unique_ptr<FnArg>> &attrs,
-          std::vector<std::unique_ptr<FnDef>> &members)
-      : Stmt(location), name(name), attrs(std::move(attrs)),
-        members(std::move(members)) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<TypeDef> fromJson(boost::json::value json);
-};
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Stmt/ValDecl.h b/compiler/include/AST/Stmt/ValDecl.h
deleted file mode 100644
index 3f65947..0000000
--- a/compiler/include/AST/Stmt/ValDecl.h
+++ /dev/null
@@ -1,24 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <memory>
-#include <string>
-
-namespace plsm {
-namespace ast {
-class ValDecl : public Stmt {
-  const std::string name;
-  const std::unique_ptr<Type> type;
-  const std::unique_ptr<Expr> value;
-
-public:
-  ValDecl(LOC_ARG, const std::string &name, std::unique_ptr<Type> &type,
-          std::unique_ptr<Expr> &value)
-      : Stmt(location), name(name), type(std::move(type)),
-        value(std::move(value)) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<ValDecl> fromJson(boost::json::value json);
-};
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Stmt/VarDecl.h b/compiler/include/AST/Stmt/VarDecl.h
new file mode 100644
index 0000000..10c01f8
--- /dev/null
+++ b/compiler/include/AST/Stmt/VarDecl.h
@@ -0,0 +1,26 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <memory>
+#include <string>
+
+namespace plsm {
+namespace ast {
+
+class VarDecl : public Stmt {
+  const std::string name;
+  const std::shared_ptr<TypeName> typeName;
+
+public:
+  VarDecl(LOC_ARG, const std::string &name, TypeName *typeName)
+      : Stmt(sourceRange), name(name), typeName(typeName) {}
+
+  virtual boost::json::value toJson() override;
+  static VarDecl *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
+};
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/include/AST/Stmt/WhileStmt.h b/compiler/include/AST/Stmt/WhileStmt.h
new file mode 100644
index 0000000..5b1318d
--- /dev/null
+++ b/compiler/include/AST/Stmt/WhileStmt.h
@@ -0,0 +1,29 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <memory>
+#include <vector>
+
+namespace plsm {
+namespace ast {
+class WhileStmt : public Stmt {
+  const std::shared_ptr<Expr> condition;
+  std::vector<std::shared_ptr<Stmt>> body;
+
+public:
+  WhileStmt(LOC_ARG, Expr *condition, const std::vector<Stmt *> &body)
+      : Stmt(sourceRange), condition(condition) {
+    for (auto &stmt : body) {
+      this->body.push_back(std::shared_ptr<Stmt>(stmt));
+    }
+  }
+
+  virtual boost::json::value toJson() override;
+  static WhileStmt *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
+};
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/include/AST/Type/Closure.h b/compiler/include/AST/Type/Closure.h
deleted file mode 100644
index 06a432f..0000000
--- a/compiler/include/AST/Type/Closure.h
+++ /dev/null
@@ -1,23 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <memory>
-#include <vector>
-
-namespace plsm {
-namespace ast {
-class ClosureType : public Type {
-  const std::vector<std::unique_ptr<Type>> from;
-  const std::unique_ptr<Type> to;
-
-public:
-  ClosureType(LOC_ARG, std::vector<std::unique_ptr<Type>> &from,
-              std::unique_ptr<Type> &to)
-      : Type(location), from(std::move(from)), to(std::move(to)) {}
-
-  
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<ClosureType> fromJson(boost::json::value json);
-};
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Type/FunctionType.h b/compiler/include/AST/Type/FunctionType.h
new file mode 100644
index 0000000..d23c2ab
--- /dev/null
+++ b/compiler/include/AST/Type/FunctionType.h
@@ -0,0 +1,25 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <memory>
+#include <vector>
+
+namespace plsm {
+namespace ast {
+class FunctionType : public Type {
+  std::vector<std::unique_ptr<Type>> paramTypes;
+  const std::unique_ptr<Type> returnType;
+
+public:
+  FunctionType(const std::vector<Type *> &paramTypes, Type *returnType)
+      : Type(), returnType(returnType) {
+    for (auto &paramType : paramTypes) {
+      this->paramTypes.push_back(std::unique_ptr<Type>(paramType));
+    }
+  }
+
+  virtual boost::json::value toJson() override;
+  static FunctionType *fromJson(boost::json::value json);
+};
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/include/AST/Type/Generic.h b/compiler/include/AST/Type/Generic.h
deleted file mode 100644
index 33443d0..0000000
--- a/compiler/include/AST/Type/Generic.h
+++ /dev/null
@@ -1,23 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <memory>
-#include <string>
-#include <vector>
-
-namespace plsm {
-namespace ast {
-class GenericType : public Type {
-  const std::string name;
-  const std::vector<std::unique_ptr<Type>> types;
-
-public:
-  GenericType(LOC_ARG, const std::string &name,
-              std::vector<std::unique_ptr<Type>> &types)
-      : Type(location), name(name), types(std::move(types)) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<GenericType> fromJson(boost::json::value json);
-};
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Type/Named.h b/compiler/include/AST/Type/Named.h
deleted file mode 100644
index bb51a49..0000000
--- a/compiler/include/AST/Type/Named.h
+++ /dev/null
@@ -1,20 +0,0 @@
-#pragma once
-
-#include "AST/Base.h"
-#include <string>
-
-namespace plsm {
-namespace ast {
-
-class NamedType : public Type {
-  const std::string name;
-
-public:
-  NamedType(LOC_ARG, const std::string &name) : Type(location), name(name) {}
-
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<NamedType> fromJson(boost::json::value json);
-};
-
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/Type/PrimitiveType.h b/compiler/include/AST/Type/PrimitiveType.h
new file mode 100644
index 0000000..ecc10a3
--- /dev/null
+++ b/compiler/include/AST/Type/PrimitiveType.h
@@ -0,0 +1,22 @@
+#pragma once
+
+#include "AST/Base.h"
+
+namespace plsm {
+namespace ast {
+
+class PrimitiveType : public Type {
+  const std::string name;
+
+public:
+  PrimitiveType(const std::string &name) : Type(), name(name) {}
+
+  bool operator==(const PrimitiveType &other) { return name == other.name; }
+  bool operator!=(const PrimitiveType &other) { return !(*this == other); }
+
+  virtual boost::json::value toJson() override;
+  static PrimitiveType *fromJson(boost::json::value json);
+};
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/include/AST/Type/Tuple.h b/compiler/include/AST/Type/Tuple.h
deleted file mode 100644
index b80f4ec..0000000
--- a/compiler/include/AST/Type/Tuple.h
+++ /dev/null
@@ -1,21 +0,0 @@
-#pragma once
-
-#include "AST/Def.h"
-#include <memory>
-#include <vector>
-
-namespace plsm {
-namespace ast {
-class TupleType : public Type {
-  const std::vector<std::unique_ptr<Type>> types;
-
-public:
-  TupleType(LOC_ARG, std::vector<std::unique_ptr<Type>> &types)
-      : Type(location), types(std::move(types)) {}
-
-  
-  virtual boost::json::value toJson() override;
-  static std::unique_ptr<TupleType> fromJson(boost::json::value json);
-};
-} // namespace ast
-} // namespace plsm
diff --git a/compiler/include/AST/TypeName/PrimitiveTypeName.h b/compiler/include/AST/TypeName/PrimitiveTypeName.h
new file mode 100644
index 0000000..282557e
--- /dev/null
+++ b/compiler/include/AST/TypeName/PrimitiveTypeName.h
@@ -0,0 +1,27 @@
+#pragma once
+
+#include "AST/Base.h"
+
+namespace plsm {
+namespace ast {
+
+class PrimitiveTypeName : public TypeName {
+  const std::string name;
+
+public:
+  PrimitiveTypeName(LOC_ARG, const std::string &name)
+      : TypeName(sourceRange), name(name) {}
+
+  bool operator==(const PrimitiveTypeName &other) { return name == other.name; }
+  bool operator!=(const PrimitiveTypeName &other) { return !(*this == other); }
+
+  virtual boost::json::value toJson() override;
+  static PrimitiveTypeName *fromJson(boost::json::value json);
+
+  virtual std::any accept(ASTVisitor *visitor, std::any param) override {
+    return visitor->visit(*this, param);
+  }
+};
+
+} // namespace ast
+} // namespace plsm
\ No newline at end of file
diff --git a/compiler/include/Parser.h b/compiler/include/Parser.h
index 2904152..1d509d4 100644
--- a/compiler/include/Parser.h
+++ b/compiler/include/Parser.h
@@ -1,12 +1,11 @@
 #pragma once
 
-#include <string>
 #include <stdexcept>
+#include <string>
 
-#include "AST/Def.h"
+#include "AST/AST.h"
 
-namespace plsm
-{
-  std::unique_ptr<ast::Module> parse(const std::string &file, const std::string &input);
+namespace plsm {
+std::shared_ptr<ast::Module> parse(const std::string &file,
+                                   const std::string &input);
 }
-
diff --git a/compiler/plsm.g4 b/compiler/plsm.g4
index 56493b4..cfd408a 100644
--- a/compiler/plsm.g4
+++ b/compiler/plsm.g4
@@ -1,84 +1,323 @@
 grammar plsm;
 
-module: MODULE identifier ';' moduleImport* moduleStmt*;
+@parser::header {
+#include "AST/AST.h"
 
-moduleImport: IMPORT importName ';';
-importName: identifier ('/' identifier)*;
-moduleStmt: let | fnDecl | fnDef | traitDef | typeDef;
+using namespace plsm::ast;
+}
 
-traitDef: TRAIT identifier '=' identifier ';'
-        | TRAIT identifier '=' '{' (fnDecl)* '}' ';';
+@parser::members {
 
-typeDef: TYPE identifier '=' type ';'
-       | TYPE identifier '=' ('(' fnDefArgs ')')? '{' (fnDecl | fnDef)* '}' ';';
+std::string filename;
 
-fnDef: FN identifier '[' fnDefArgs? ']' type '=' expr ';';
-fnDefArgs: identifier type (',' identifier type)*;
+void setFileName(const std::string &filename) { this->filename = filename; }
 
-fnDecl: FN identifier '[' fnDeclArgs? ']' type ';';
-fnDeclArgs: identifier? type (',' identifier? type)*;
+inline SourceRange getSourceRange(antlr4::ParserRuleContext *ctx) {
+     if (!ctx->getStart() || !ctx->getStop()) {
+          return SourceRange::unknown();
+     }
 
-let: LET identifier type? '=' expr ';';
+     return SourceRange(
+          filename, ctx->getText(),
+          std::pair<size_t, size_t>(ctx->getStart()->getLine(),
+                                    ctx->getStart()->getCharPositionInLine()),
+          std::pair<size_t, size_t>(ctx->getStop()->getLine(),
+                                    ctx->getStop()->getCharPositionInLine()));
+}
 
-exprStmt: expr ';';
+}
 
-type: type1; // novisit
-type1: type0
-     | '(' type ')'
-     | '(' tupleTypeList ')'          // tuple
-     | '[' typeList? ']' '->' type;   // closure
-type0: identifier
-     | identifier '{' typeList '}';   // generic
+module
+	returns[Module *ast]: (stmts += topLevelStmt)* {
+          std::vector<Stmt *> stmts;
+          for (auto &stmt : $ctx->stmts) {
+               stmts.push_back(stmt->ast);
+          }
 
-tupleTypeList: type (',' type)+;
-typeList: type (',' type)*;
+          $ast = new Module(getSourceRange($ctx), "default", std::vector<Import *>(), stmts);
+     };
+
+topLevelStmt
+	returns[Stmt *ast]:
+	varDecl {
+          $ast = $ctx->varDecl()->ast;
+     }
+	| fnDecl {
+          $ast = $ctx->fnDecl()->ast;
+     };
+
+stmt
+	returns[Stmt *ast]:
+	exprStmt {
+          $ast = $ctx->exprStmt()->ast;
+     }
+	| varDecl {
+          $ast = $ctx->varDecl()->ast;
+     }
+	| retStmt {
+          $ast = $ctx->retStmt()->ast;
+     }
+	| assignStmt {
+          $ast = $ctx->assignStmt()->ast;
+     }
+	| implDeclAssignStmt {
+          $ast = $ctx->implDeclAssignStmt()->ast;
+     }
+	| ifStmt {
+          $ast = $ctx->ifStmt()->ast;
+     }
+	| whileStmt {
+          $ast = $ctx->whileStmt()->ast;
+     };
+
+whileStmt
+	returns[WhileStmt *ast]:
+	'while' '(' condition = expr ')' (
+		'{' (stmts += stmt)* '}'
+		| singleStmt = stmt
+	) {
+          auto cond = $ctx->condition->ast;
+
+          std::vector<Stmt *> body;
+          for (auto &stmt : $ctx->stmts) {
+               body.push_back(stmt->ast);
+          }
+          if ($ctx->singleStmt) body.push_back($ctx->singleStmt->ast);
+
+          $ast = new WhileStmt(getSourceRange($ctx), cond, body);
+     };
+
+ifStmt
+	returns[IfStmt *ast]:
+	'if' '(' condition = expr ')' (
+		'{' (ifStmts += stmt)* '}'
+		| ifSingleStmt = stmt
+	) (
+		'else' (
+			'{' (elseStmts += stmt)* '}'
+			| elseSingleStmt = stmt
+		)
+	)? {
+          auto cond = $ctx->condition->ast;
+
+          std::vector<Stmt *> ifBody;
+          for (auto &stmt : $ctx->ifStmts) {
+               ifBody.push_back(stmt->ast);
+          }
+          if ($ctx->ifSingleStmt) ifBody.push_back($ctx->ifSingleStmt->ast);
 
 
-expr: expr3; // novisit
-expr3: expr2
-     | '[' fnDefArgs? ']' '->' expr     // closure
-     | '{' blockStmt* (expr ';') '}';
-expr2: expr1
-     | expr2 operator expr1;        // binary expr
-expr1: expr0
-     | operator expr0;              // unary expr
-expr0: literal
-     | identifier
-     | expr0 '[' exprList? ']'      // fn call
-     | '(' expr ')'
-     | '(' tupleExprList ')'        // tuple
-     | expr0 '.' identifier;        // property accessor
+          std::vector<Stmt *> elseBody;
+          for (auto &stmt : $ctx->elseStmts) {
+               elseBody.push_back(stmt->ast);
+          }
+          if ($ctx->elseSingleStmt) elseBody.push_back($ctx->elseSingleStmt->ast);
 
-blockStmt: let | exprStmt | fnDef;
-tupleExprList: expr (',' expr)+;
-exprList: expr (',' expr)*;
+          $ast = new IfStmt(getSourceRange($ctx), cond, ifBody, elseBody);
+     };
 
-identifierList: identifier (',' identifier)*;
+implDeclAssignStmt
+	returns[Stmt *ast]:
+	IDENTIFIER ':=' expr {
+          // TODO
+     };
 
-literal: NULL='null' | INT_LIT | FLOAT_LIT;
+assignStmt
+	returns[AssignStmt *ast]:
+	lval = expr '=' rval = expr {
+          $ast = new AssignStmt(getSourceRange($ctx), $ctx->lval->ast, $ctx->rval->ast);
+     };
 
-operator: '=' | '->'
-        | OPERATOR;
+retStmt
+	returns[RetStmt *ast]:
+	'ret' expr ';' {
+          $ast = new RetStmt(getSourceRange($ctx), $ctx->expr()->ast);
+     };
 
-identifier: keyword | IDENTIFIER;
-keyword: BINOP | FN | IMPORT | LET | MODULE | NATIVE | TRAIT | TYPE | UNOP;
+fnDecl
+	returns[FnDecl *ast]:
+	'fun' name = IDENTIFIER '(' (
+		params += fnParam (',' params += fnParam)*
+	)? ')' typeName '{' (stmts += stmt)* '}' {
+          auto name = $ctx->name->getText();
 
+          std::vector<FnParam *> params;
+          for (auto &param : $ctx->params) {
+               params.push_back(param->ast);
+          }
 
-INT_LIT: [0-9]+ | '0x' [0-9a-fA-F]+ | '0o' [0-7]+ | '0b' [01]+;
-FLOAT_LIT: [0-9]+ '.' | [0-9]* '.' [0-9]+;
+          auto returnTypeName = $ctx->typeName()->ast;
 
-OPERATOR: ('+'|'-'|'*'|'/'|'%'|'!'|'&'|'$'|'§'|'|'|'='|'<'|'>'|'?'|'~'|'#'|':'|'^'|'\\'|'.')+;
+          std::vector<Stmt *> body;
+          for (auto &stmt : $ctx->stmts) {
+               body.push_back(stmt->ast);
+          }
 
-BINOP: 'binop';
-FN: 'fn';
-IMPORT: 'import';
-LET: 'let';
-MODULE: 'module';
-NATIVE: 'native';
-TRAIT: 'trait';
-TYPE: 'type';
-UNOP: 'unop';
+          $ast = new FnDecl(getSourceRange($ctx), name, params, returnTypeName, body);
+     };
+
+fnParam
+	returns[FnParam *ast]:
+	IDENTIFIER typeName {
+          $ast = new FnParam(getSourceRange($ctx), $ctx->IDENTIFIER()->getText(), $ctx->typeName()->ast);
+     };
+
+varDecl
+	returns[VarDecl *ast]:
+	'var' IDENTIFIER ':' typeName ';' {
+          auto name = $ctx->IDENTIFIER()->getText();
+          $ast = new VarDecl(getSourceRange($ctx), name, $ctx->typeName()->ast);
+     };
+
+exprStmt
+	returns[ExprStmt *ast]:
+	expr ';' {
+          $ast = new ExprStmt(getSourceRange($ctx), $ctx->expr()->ast);
+     };
+
+expr
+	returns[Expr *ast]:
+	value = binaryExpr {
+          $ast = $ctx->value->ast;
+     };
+
+binaryExpr
+	returns[Expr *ast]:
+	value = unaryExpr {
+          $ast = $ctx->value->ast;
+     }
+	| lhs = binaryExpr op = ('*' | '/' | '%') rhs = binaryExpr {
+          auto opText = $ctx->op->getText();
+
+          BinOp op;
+          if (opText == "*") op = BinOp::MUL;
+          if (opText == "/") op = BinOp::DIV;
+          if (opText == "%") op = BinOp::MOD;
+
+          $ast = new BinExpr(getSourceRange($ctx), op, $ctx->lhs->ast, $ctx->rhs->ast);
+     }
+	| lhs = binaryExpr op = ('+' | '-') rhs = binaryExpr {
+          auto opText = $ctx->op->getText();
+
+          BinOp op;
+          if (opText == "+") op = BinOp::ADD;
+          if (opText == "-") op = BinOp::SUB;
+
+          $ast = new BinExpr(getSourceRange($ctx), op, $ctx->lhs->ast, $ctx->rhs->ast);
+     }
+	| operand = binaryExpr 'as' typeName {
+          $ast = new CastExpr(getSourceRange($ctx), $ctx->operand->ast, $ctx->typeName()->ast);
+     }
+	| lhs = binaryExpr op = (
+		'=='
+		| '!='
+		| '>='
+		| '<='
+		| '>'
+		| '<'
+	) rhs = binaryExpr {
+          auto opText = $ctx->op->getText();
+
+          BinOp op;
+          if (opText == "==") op = BinOp::EQ;
+          if (opText == "!=") op = BinOp::NE;
+          if (opText == ">=") op = BinOp::GE;
+          if (opText == "<=") op = BinOp::LE;
+          if (opText == ">") op = BinOp::GT;
+          if (opText == "<") op = BinOp::LT;
+
+          $ast = new BinExpr(getSourceRange($ctx), op, $ctx->lhs->ast, $ctx->rhs->ast);
+     }
+	| lhs = binaryExpr '&&' rhs = binaryExpr {
+          $ast = new BinExpr(getSourceRange($ctx), BinOp::AND, $ctx->lhs->ast, $ctx->rhs->ast);
+     }
+	| lhs = binaryExpr '||' rhs = binaryExpr {
+          $ast = new BinExpr(getSourceRange($ctx), BinOp::OR, $ctx->lhs->ast, $ctx->rhs->ast);
+     };
+
+unaryExpr
+	returns[Expr *ast]:
+	factorExpr {
+          $ast = $ctx->factorExpr()->ast;
+     }
+	| functionCall {
+          $ast = $ctx->functionCall()->ast;
+     }
+	| '!' unaryExpr {
+          $ast = new UnExpr(getSourceRange($ctx), UnOp::NOT, $ctx->unaryExpr()->ast);
+     }
+	| '+' unaryExpr {
+          $ast = new UnExpr(getSourceRange($ctx), UnOp::POS, $ctx->unaryExpr()->ast);
+     }
+	| '-' unaryExpr {
+          $ast = new UnExpr(getSourceRange($ctx), UnOp::NEG, $ctx->unaryExpr()->ast);
+     };
+
+factorExpr
+	returns[Expr *ast]:
+	IDENTIFIER {
+          $ast = new Identifier(getSourceRange($ctx), $ctx->IDENTIFIER()->getText());
+     }
+	| INT {
+          auto text = $ctx->INT()->getText();
+
+          int64_t value;
+
+          if (!text.rfind("0x", 0))
+               value = std::strtol(text.substr(2).data(), NULL, 16);
+
+          else if (!text.rfind("0o", 0))
+               value = std::strtol(text.substr(2).data(), NULL, 8);
+
+          else if (!text.rfind("0b", 0))
+               value = std::strtol(text.substr(2).data(), NULL, 2);
+
+          else
+               value = std::strtol(text.data(), NULL, 10);
+
+          $ast = new IntValue(getSourceRange($ctx), value);
+     }
+	| FLOAT {
+          auto text = $ctx->FLOAT()->getText();
+
+          if (text.at(text.size() - 1) == '.')
+               text += "0";
+          if (text.at(0) == '0')
+               text = "0" + text;
+
+          double value = std::strtod(text.data(), NULL);
+          $ast = new FloatValue(getSourceRange($ctx), value);
+     }
+	| BOOL {
+          auto text = $ctx->BOOL()->getText();
+          $ast = new IntValue(getSourceRange($ctx), text == "true" ? 1 : 0);
+     }
+	| '(' expr ')' {
+          $ast = $ctx->expr()->ast;
+     };
+
+functionCall
+	returns[Expr *ast]:
+	callee = factorExpr '(' (args += expr (',' args += expr)*)? ')' {
+          std::vector<Expr *> args;
+          for (auto &arg : $ctx->args) {
+               args.push_back(arg->ast);
+          }
+
+          $ast = new CallExpr(getSourceRange($ctx), $ctx->callee->ast, args);
+     };
+
+typeName
+	returns[TypeName *ast]:
+	IDENTIFIER {
+          auto text = $ctx->IDENTIFIER()->getText();
+          $ast = new PrimitiveTypeName(getSourceRange($ctx), text);
+     };
+
+INT: [0-9]+ | '0x' [0-9a-fA-F]+ | '0o' [0-7]+ | '0b' [01]+;
+FLOAT: [0-9]+ '.' | [0-9]* '.' [0-9]+;
+BOOL: 'true' | 'false';
 
 IDENTIFIER: [a-zA-Z_] [a-zA-Z0-9_]*;
 
-WHITESPACE: [ \r\n\t]+ -> skip;
+WHITESPACE: [ \r\n\t]+ -> skip;
\ No newline at end of file
diff --git a/compiler/src/AST/Base.cpp b/compiler/src/AST/Base.cpp
index 2ac86ff..fca60f8 100644
--- a/compiler/src/AST/Base.cpp
+++ b/compiler/src/AST/Base.cpp
@@ -1,23 +1,21 @@
-#include "AST/Def.h"
-#include "AST/Expr/BinExpr.h"
-#include "AST/Expr/Value.h"
+#include "AST/AST.h"
 
 #include <map>
 #include <memory>
 #include <stdexcept>
 
 namespace plsm {
+namespace ast {
 
-std::unique_ptr<ast::ASTNode> ast::ASTNode::fromJson(boost::json::value json) {
-  if (json.is_null())
-    return std::make_unique<NullValue>(ast::Location::json());
+ASTNode *ASTNode::fromJson(boost::json::value json) {
+  // if (json.is_null())
+  //   return std::make_unique<NullValue>(Location::json());
 
   if (json.is_int64())
-    return std::make_unique<IntValue>(ast::Location::json(), json.as_int64());
+    return new IntValue(SourceRange::json(), json.as_int64());
 
   if (json.is_double())
-    return std::make_unique<FloatValue>(ast::Location::json(),
-                                        json.as_double());
+    return new FloatValue(SourceRange::json(), json.as_double());
 
   std::string type;
   try {
@@ -28,86 +26,93 @@ std::unique_ptr<ast::ASTNode> ast::ASTNode::fromJson(boost::json::value json) {
   }
 
   if (type == "BinExpr")
-    return ast::BinExpr::fromJson(json);
-  if (type == "BlockExpr")
-    return ast::BlockExpr::fromJson(json);
+    return BinExpr::fromJson(json);
   if (type == "CallExpr")
-    return ast::CallExpr::fromJson(json);
-  if (type == "Closure")
-    return ast::Closure::fromJson(json);
+    return CallExpr::fromJson(json);
+  if (type == "CastExpr")
+    return CastExpr::fromJson(json);
   if (type == "Identifier")
-    return ast::Identifier::fromJson(json);
-  if (type == "PropExpr")
-    return ast::PropExpr::fromJson(json);
-  if (type == "Tuple")
-    return ast::Tuple::fromJson(json);
-  if (type == "UnaryExpr")
-    return ast::UnaryExpr::fromJson(json);
-
-  if (type == "Import")
-    return ast::Import::fromJson(json);
-  if (type == "Module")
-    return ast::Module::fromJson(json);
+    return Identifier::fromJson(json);
+  if (type == "LambdaExpr")
+    return LambdaExpr::fromJson(json);
+  if (type == "LambdaExpr")
+    return LambdaExpr::fromJson(json);
+  if (type == "UnExpr")
+    return UnExpr::fromJson(json);
 
+  if (type == "AssignStmt")
+    return AssignStmt::fromJson(json);
   if (type == "ExprStmt")
-    return ast::ExprStmt::fromJson(json);
-  if (type == "FnDef")
-    return ast::FnDef::fromJson(json);
-  if (type == "TraitAlias")
-    return ast::TraitAlias::fromJson(json);
-  if (type == "TraitDef")
-    return ast::TraitDef::fromJson(json);
-  if (type == "TypeAlias")
-    return ast::TypeAlias::fromJson(json);
-  if (type == "TypeDef")
-    return ast::TypeDef::fromJson(json);
-  if (type == "ValDecl")
-    return ast::ValDecl::fromJson(json);
+    return ExprStmt::fromJson(json);
+  if (type == "FnParam")
+    return FnParam::fromJson(json);
+  if (type == "FnDecl")
+    return FnDecl::fromJson(json);
+  if (type == "IfStmt")
+    return IfStmt::fromJson(json);
+  if (type == "RetStmt")
+    return RetStmt::fromJson(json);
+  if (type == "VarDecl")
+    return VarDecl::fromJson(json);
+  if (type == "WhileStmt")
+    return WhileStmt::fromJson(json);
 
-  if (type == "ClosureType")
-    return ast::ClosureType::fromJson(json);
-  if (type == "GenericType")
-    return ast::GenericType::fromJson(json);
-  if (type == "NamedType")
-    return ast::NamedType::fromJson(json);
-  if (type == "TupleType")
-    return ast::TupleType::fromJson(json);
+  if (type == "PrimitiveTypeName")
+    return PrimitiveTypeName::fromJson(json);
 
   throw std::runtime_error("json conversion for '" + type +
                            "' not implemented");
 }
 
-std::unique_ptr<ast::Expr> ast::Expr::fromJson(boost::json::value json) {
-  auto node = ast::ASTNode::fromJson(json);
+Expr *Expr::fromJson(boost::json::value json) {
+  auto node = ASTNode::fromJson(json);
 
-  if (dynamic_cast<ast::Expr *>(node.get())) {
-    return std::unique_ptr<ast::Expr>((ast::Expr *)node.release());
+  if (dynamic_cast<Expr *>(node)) {
+    return (Expr *)node;
   }
 
   throw std::runtime_error(json.as_object().at("@type").as_string().c_str() +
                            std::string(" is not of type 'Expr'"));
 }
 
-std::unique_ptr<ast::Type> ast::Type::fromJson(boost::json::value json) {
-  auto node = ast::ASTNode::fromJson(json);
+TypeName *TypeName::fromJson(boost::json::value json) {
+  auto node = ASTNode::fromJson(json);
 
-  if (dynamic_cast<ast::Type *>(node.get())) {
-    return std::unique_ptr<ast::Type>((ast::Type *)node.release());
+  if (dynamic_cast<TypeName *>(node)) {
+    return (TypeName *)node;
   }
 
   throw std::runtime_error(json.as_object().at("@type").as_string().c_str() +
-                           std::string(" is not of type 'Type'"));
+                           std::string(" is not of type 'TypeName'"));
 }
 
-std::unique_ptr<ast::Stmt> ast::Stmt::fromJson(boost::json::value json) {
-  auto node = ast::ASTNode::fromJson(json);
+Stmt *Stmt::fromJson(boost::json::value json) {
+  auto node = ASTNode::fromJson(json);
 
-  if (dynamic_cast<ast::Stmt *>(node.get())) {
-    return std::unique_ptr<ast::Stmt>((ast::Stmt *)node.release());
+  if (dynamic_cast<Stmt *>(node)) {
+    return (Stmt *)node;
   }
 
   throw std::runtime_error(json.as_object().at("@type").as_string().c_str() +
                            std::string(" is not of type 'Stmt'"));
 }
 
-} // namespace plsm
+Type *Type::fromJson(boost::json::value json) {
+  std::string type;
+  try {
+    type = json.as_object().at("@type").as_string().c_str();
+  } catch (...) {
+    throw std::runtime_error("called Type::fromJson without @type constraint");
+  }
+
+  if (type == "FunctionType")
+    return FunctionType::fromJson(json);
+  if (type == "PrimitiveType")
+    return PrimitiveType::fromJson(json);
+
+  throw std::runtime_error("json conversion for '" + type +
+                           "' not implemented");
+}
+
+} // namespace ast
+} // namespace plsm
\ No newline at end of file
diff --git a/compiler/src/AST/Expr/BinExpr.cpp b/compiler/src/AST/Expr/BinExpr.cpp
index 4a76f25..9bd646b 100644
--- a/compiler/src/AST/Expr/BinExpr.cpp
+++ b/compiler/src/AST/Expr/BinExpr.cpp
@@ -1,37 +1,41 @@
-#include "AST/Expr/BinExpr.h"
-#include "AST/Base.h"
-#include "AST/Def.h"
+#include "AST/AST.h"
 #include <memory>
 
 namespace plsm {
+namespace ast {
 
-boost::json::value ast::BinExpr::toJson() {
+static const std::unordered_map<BinOp, std::string> binOpToString = {
+    {BinOp::ADD, "+"}, {BinOp::SUB, "-"}, {BinOp::MUL, "*"}, {BinOp::DIV, "/"},
+    {BinOp::MOD, "%"}, {BinOp::EQ, "=="}, {BinOp::NE, "!="}, {BinOp::LT, "<"},
+    {BinOp::LE, "<="}, {BinOp::GT, ">"},  {BinOp::GE, ">="}, {BinOp::AND, "&&"},
+    {BinOp::OR, "||"},
+};
+
+static const std::unordered_map<std::string, BinOp> stringToBinOp = {
+    {"+", BinOp::ADD}, {"-", BinOp::SUB}, {"*", BinOp::MUL}, {"/", BinOp::DIV},
+    {"%", BinOp::MOD}, {"==", BinOp::EQ}, {"!=", BinOp::NE}, {"<", BinOp::LT},
+    {"<=", BinOp::LE}, {">", BinOp::GT},  {">=", BinOp::GE}, {"&&", BinOp::AND},
+    {"||", BinOp::OR},
+};
+
+boost::json::value BinExpr::toJson() {
   return {
       {"@type", "BinExpr"},
-      {"op", op},
-      {"left", left->toJson()},
-      {"right", right->toJson()},
+      {"op", binOpToString.at(op)},
+      {"lhs", lhs->toJson()},
+      {"rhs", rhs->toJson()},
   };
 }
 
-std::unique_ptr<ast::BinExpr> ast::BinExpr::fromJson(boost::json::value json) {
-  auto op = getJsonValue<ast::BinExpr, std::string>(json, "op");
-  auto left = fromJsonProperty<ast::BinExpr, ast::Expr>(json, "left");
-  auto right = fromJsonProperty<ast::BinExpr, ast::Expr>(json, "right");
-  return std::make_unique<ast::BinExpr>(ast::Location::json(), left, op, right);
-}
-
-boost::json::value ast::PrefExpr::toJson() {
-  return {
-      {"@type", "PrefExpr"},
-      {"expr", expr->toJson()},
-  };
-}
-
-std::unique_ptr<ast::PrefExpr>
-ast::PrefExpr::fromJson(boost::json::value json) {
-  auto expr = fromJsonProperty<ast::PrefExpr, ast::Expr>(json, "expr");
-  return std::make_unique<ast::PrefExpr>(ast::Location::json(), expr);
+BinExpr *BinExpr::fromJson(boost::json::value json) {
+  auto opString = getJsonValue<BinExpr, std::string>(json, "op");
+  auto op = stringToBinOp.at(opString);
+
+  auto lhs = fromJsonProperty<BinExpr, Expr>(json, "lhs");
+  auto rhs = fromJsonProperty<BinExpr, Expr>(json, "rhs");
+
+  return new BinExpr(SourceRange::json(), op, lhs, rhs);
 }
 
+} // namespace ast
 } // namespace plsm
diff --git a/compiler/src/AST/Expr/Block.cpp b/compiler/src/AST/Expr/Block.cpp
deleted file mode 100644
index 0bbe462..0000000
--- a/compiler/src/AST/Expr/Block.cpp
+++ /dev/null
@@ -1,25 +0,0 @@
-#include "AST/Expr/Block.h"
-#include "AST/Base.h"
-#include "AST/Def.h"
-#include "Utils.h"
-#include <algorithm>
-#include <memory>
-
-namespace plsm {
-
-boost::json::value ast::BlockExpr::toJson() {
-  return {
-      {"@type", "BlockExpr"},
-      {"stmts", utils::mapToJson(stmts)},
-      {"result", result->toJson()},
-  };
-}
-
-std::unique_ptr<ast::BlockExpr>
-ast::BlockExpr::fromJson(boost::json::value json) {
-  auto stmts = fromJsonVector<ast::BlockExpr, ast::Stmt>(json, "stmts");
-  auto result = fromJsonProperty<ast::BlockExpr, ast::Expr>(json, "result");
-  return std::make_unique<ast::BlockExpr>(ast::Location::json(), stmts, result);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Expr/Call.cpp b/compiler/src/AST/Expr/Call.cpp
deleted file mode 100644
index 8661951..0000000
--- a/compiler/src/AST/Expr/Call.cpp
+++ /dev/null
@@ -1,22 +0,0 @@
-#include "AST/Expr/Call.h"
-#include "AST/Def.h"
-#include "Utils.h"
-
-namespace plsm {
-
-boost::json::value ast::CallExpr::toJson() {
-  return {
-      {"@type", "CallExpr"},
-      {"callee", callee->toJson()},
-      {"args", utils::mapToJson(args)},
-  };
-}
-
-std::unique_ptr<ast::CallExpr>
-ast::CallExpr::fromJson(boost::json::value json) {
-  auto callee = fromJsonProperty<ast::CallExpr, ast::Expr>(json, "callee");
-  auto args = fromJsonVector<ast::CallExpr, ast::Expr>(json, "args");
-  return std::make_unique<ast::CallExpr>(ast::Location::json(), callee, args);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Expr/CallExpr.cpp b/compiler/src/AST/Expr/CallExpr.cpp
new file mode 100644
index 0000000..aa1d1bc
--- /dev/null
+++ b/compiler/src/AST/Expr/CallExpr.cpp
@@ -0,0 +1,22 @@
+#include "AST/AST.h"
+#include "Utils.h"
+
+namespace plsm {
+namespace ast {
+
+boost::json::value CallExpr::toJson() {
+  return {
+      {"@type", "CallExpr"},
+      {"callee", callee->toJson()},
+      {"args", utils::mapToJson(args)},
+  };
+}
+
+CallExpr *CallExpr::fromJson(boost::json::value json) {
+  auto callee = fromJsonProperty<CallExpr, Expr>(json, "callee");
+  auto args = fromJsonVector<CallExpr, Expr>(json, "args");
+  return new CallExpr(SourceRange::json(), callee, args);
+}
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/src/AST/Expr/CastExpr.cpp b/compiler/src/AST/Expr/CastExpr.cpp
new file mode 100644
index 0000000..a85d53e
--- /dev/null
+++ b/compiler/src/AST/Expr/CastExpr.cpp
@@ -0,0 +1,22 @@
+#include "AST/AST.h"
+#include "Utils.h"
+
+namespace plsm {
+namespace ast {
+
+boost::json::value CastExpr::toJson() {
+  return {
+      {"@type", "CastExpr"},
+      {"value", value->toJson()},
+      {"typeName", typeName->toJson()},
+  };
+}
+
+CastExpr *CastExpr::fromJson(boost::json::value json) {
+  auto value = fromJsonProperty<CastExpr, Expr>(json, "value");
+  auto typeName = fromJsonProperty<CastExpr, TypeName>(json, "typeName");
+  return new CastExpr(SourceRange::json(), value, typeName);
+}
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/src/AST/Expr/Closure.cpp b/compiler/src/AST/Expr/Closure.cpp
deleted file mode 100644
index 8d3f26a..0000000
--- a/compiler/src/AST/Expr/Closure.cpp
+++ /dev/null
@@ -1,20 +0,0 @@
-#include "AST/Def.h"
-#include "Utils.h"
-
-namespace plsm {
-
-boost::json::value ast::Closure::toJson() {
-  return {
-      {"@type", "Closure"},
-      {"args", utils::mapToJson(args)},
-      {"body", body->toJson()},
-  };
-}
-
-std::unique_ptr<ast::Closure> ast::Closure::fromJson(boost::json::value json) {
-  auto args = fromJsonVector<ast::Closure, ast::FnArg>(json, "args");
-  auto body = fromJsonProperty<ast::Closure, ast::Expr>(json, "body");
-  return std::make_unique<ast::Closure>(ast::Location::json(), args, body);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Expr/Identifier.cpp b/compiler/src/AST/Expr/Identifier.cpp
index 8ea1fb8..10aa811 100644
--- a/compiler/src/AST/Expr/Identifier.cpp
+++ b/compiler/src/AST/Expr/Identifier.cpp
@@ -1,19 +1,19 @@
-#include "AST/Def.h"
-#include "AST/Expr/Identifier.h"
+#include "AST/AST.h"
 
 namespace plsm {
+namespace ast {
 
-boost::json::value ast::Identifier::toJson() {
+boost::json::value Identifier::toJson() {
   return {
       {"@type", "Identifier"},
       {"name", name},
   };
 }
 
-std::unique_ptr<ast::Identifier>
-ast::Identifier::fromJson(boost::json::value json) {
-  auto name = getJsonValue<ast::Identifier, std::string>(json, "name");
-  return std::make_unique<ast::Identifier>(ast::Location::json(), name);
+Identifier *Identifier::fromJson(boost::json::value json) {
+  auto name = getJsonValue<Identifier, std::string>(json, "name");
+  return new Identifier(SourceRange::json(), name);
 }
 
+} // namespace ast
 } // namespace plsm
diff --git a/compiler/src/AST/Expr/LambdaExpr.cpp b/compiler/src/AST/Expr/LambdaExpr.cpp
new file mode 100644
index 0000000..1894bb8
--- /dev/null
+++ b/compiler/src/AST/Expr/LambdaExpr.cpp
@@ -0,0 +1,22 @@
+#include "AST/AST.h"
+#include "Utils.h"
+
+namespace plsm {
+namespace ast {
+
+boost::json::value LambdaExpr::toJson() {
+  return {
+      {"@type", "LambdaExpr"},
+      {"params", utils::mapToJson(params)},
+      {"body", utils::mapToJson(body)},
+  };
+}
+
+LambdaExpr *LambdaExpr::fromJson(boost::json::value json) {
+  auto params = fromJsonVector<LambdaExpr, FnParam>(json, "params");
+  auto body = fromJsonVector<LambdaExpr, Expr>(json, "body");
+  return new LambdaExpr(SourceRange::json(), params, body);
+}
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/src/AST/Expr/PropExpr.cpp b/compiler/src/AST/Expr/PropExpr.cpp
deleted file mode 100644
index 2cccd61..0000000
--- a/compiler/src/AST/Expr/PropExpr.cpp
+++ /dev/null
@@ -1,21 +0,0 @@
-#include "AST/Def.h"
-#include <memory>
-
-namespace plsm {
-
-boost::json::value ast::PropExpr::toJson() {
-  return {
-      {"@type", "PropExpr"},
-      {"expr", expr->toJson()},
-      {"property", property},
-  };
-}
-
-std::unique_ptr<ast::PropExpr>
-ast::PropExpr::fromJson(boost::json::value json) {
-  auto expr = fromJsonProperty<ast::PropExpr, ast::Expr>(json, "expr");
-  auto property = getJsonValue<ast::PropExpr, std::string>(json, "property");
-  return std::make_unique<ast::PropExpr>(ast::Location::json(), expr, property);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Expr/Tuple.cpp b/compiler/src/AST/Expr/Tuple.cpp
deleted file mode 100644
index 04ef18f..0000000
--- a/compiler/src/AST/Expr/Tuple.cpp
+++ /dev/null
@@ -1,18 +0,0 @@
-#include "AST/Def.h"
-#include "Utils.h"
-
-namespace plsm {
-
-boost::json::value ast::Tuple::toJson() {
-  return {
-      {"@type", "Tuple"},
-      {"values", utils::mapToJson(values)},
-  };
-}
-
-std::unique_ptr<ast::Tuple> ast::Tuple::fromJson(boost::json::value json) {
-  auto values = fromJsonVector<ast::Tuple, ast::Expr>(json, "values");
-  return std::make_unique<ast::Tuple>(ast::Location::json(), values);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Expr/UnExpr.cpp b/compiler/src/AST/Expr/UnExpr.cpp
new file mode 100644
index 0000000..f20d872
--- /dev/null
+++ b/compiler/src/AST/Expr/UnExpr.cpp
@@ -0,0 +1,36 @@
+#include "AST/AST.h"
+#include <memory>
+
+namespace plsm {
+namespace ast {
+
+static const std::unordered_map<UnOp, std::string> unOpToString = {
+    {UnOp::POS, "+"},
+    {UnOp::NEG, "-"},
+    {UnOp::NOT, "!"},
+};
+
+static const std::unordered_map<std::string, UnOp> stringToUnOp = {
+    {"+", UnOp::POS},
+    {"-", UnOp::NEG},
+    {"!", UnOp::NOT},
+};
+
+boost::json::value UnExpr::toJson() {
+  return {
+      {"@type", "UnExpr"},
+      {"op", unOpToString.at(op)},
+      {"expr", expr->toJson()},
+  };
+}
+
+UnExpr *UnExpr::fromJson(boost::json::value json) {
+  auto opString = getJsonValue<UnExpr, std::string>(json, "op");
+  auto op = stringToUnOp.at(opString);
+
+  auto expr = fromJsonProperty<UnExpr, Expr>(json, "expr");
+  return new UnExpr(SourceRange::json(), op, expr);
+}
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/src/AST/Expr/UnaryExpr.cpp b/compiler/src/AST/Expr/UnaryExpr.cpp
deleted file mode 100644
index 0242754..0000000
--- a/compiler/src/AST/Expr/UnaryExpr.cpp
+++ /dev/null
@@ -1,22 +0,0 @@
-#include "AST/Def.h"
-#include "AST/Expr/UnaryExpr.h"
-#include <memory>
-
-namespace plsm {
-
-boost::json::value ast::UnaryExpr::toJson() {
-  return {
-      {"@type", "UnaryExpr"},
-      {"op", op},
-      {"expr", expr->toJson()},
-  };
-}
-
-std::unique_ptr<ast::UnaryExpr>
-ast::UnaryExpr::fromJson(boost::json::value json) {
-  auto op = getJsonValue<ast::UnaryExpr, std::string>(json, "op");
-  auto expr = fromJsonProperty<ast::UnaryExpr, ast::Expr>(json, "expr");
-  return std::make_unique<ast::UnaryExpr>(ast::Location::json(), op, expr);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Expr/Value.cpp b/compiler/src/AST/Expr/Value.cpp
index 849d26c..71bc7b3 100644
--- a/compiler/src/AST/Expr/Value.cpp
+++ b/compiler/src/AST/Expr/Value.cpp
@@ -1,29 +1,26 @@
-#include "AST/Def.h"
+#include "AST/AST.h"
 #include <memory>
 
 namespace plsm {
+namespace ast {
+// boost::json::value NullValue::toJson() { return nullptr; }
 
-boost::json::value ast::NullValue::toJson() { return nullptr; }
+// std::unique_ptr<NullValue>
+// NullValue::fromJson(boost::json::value json) {
+//   return std::make_unique<NullValue>(SourceRange::json());
+// }
 
-std::unique_ptr<ast::NullValue>
-ast::NullValue::fromJson(boost::json::value json) {
-  return std::make_unique<ast::NullValue>(ast::Location::json());
+boost::json::value IntValue::toJson() { return value; }
+
+IntValue *IntValue::fromJson(boost::json::value json) {
+  return new IntValue(SourceRange::json(), json.as_int64());
 }
 
-boost::json::value ast::IntValue::toJson() { return value; }
+boost::json::value FloatValue::toJson() { return value; }
 
-std::unique_ptr<ast::IntValue>
-ast::IntValue::fromJson(boost::json::value json) {
-  return std::make_unique<ast::IntValue>(ast::Location::json(),
-                                         json.as_int64());
-}
-
-boost::json::value ast::FloatValue::toJson() { return value; }
-
-std::unique_ptr<ast::FloatValue>
-ast::FloatValue::fromJson(boost::json::value json) {
-  return std::make_unique<ast::FloatValue>(ast::Location::json(),
-                                           json.as_double());
+FloatValue *FloatValue::fromJson(boost::json::value json) {
+  return new FloatValue(SourceRange::json(), json.as_double());
 }
 
+} // namespace ast
 } // namespace plsm
diff --git a/compiler/src/AST/Module/Import.cpp b/compiler/src/AST/Module/Import.cpp
index 0d0f8a6..7dfb761 100644
--- a/compiler/src/AST/Module/Import.cpp
+++ b/compiler/src/AST/Module/Import.cpp
@@ -1,19 +1,16 @@
-#include "AST/Def.h"
+#include "AST/AST.h"
 #include <memory>
 
 namespace plsm {
+namespace ast {
 
-boost::json::value ast::Import::toJson() {
-  return {
-      {"@type", "Import"},
-      {"moduleName", moduleName}
-  };
-}
-
-std::unique_ptr<ast::Import>
-ast::Import::fromJson(boost::json::value json) {
-  auto moduleName = getJsonValue<ast::Import, std::string>(json, "moduleName");
-  return std::make_unique<ast::Import>(ast::Location::json(), moduleName);
+boost::json::value Import::toJson() {
+  return {{"@type", "Import"}, {"moduleName", moduleName}};
+}
+Import *Import::fromJson(boost::json::value json) {
+  auto moduleName = getJsonValue<Import, std::string>(json, "moduleName");
+  return new Import(SourceRange::json(), moduleName);
 }
 
+} // namespace ast
 } // namespace plsm
diff --git a/compiler/src/AST/Module/Module.cpp b/compiler/src/AST/Module/Module.cpp
index 590d890..0a2ce23 100644
--- a/compiler/src/AST/Module/Module.cpp
+++ b/compiler/src/AST/Module/Module.cpp
@@ -1,9 +1,10 @@
-#include "AST/Def.h"
+#include "AST/AST.h"
 #include "Utils.h"
 
 namespace plsm {
+namespace ast {
 
-boost::json::value ast::Module::toJson() {
+boost::json::value Module::toJson() {
   return {
       {"@type", "Module"},
       {"name", name},
@@ -12,11 +13,13 @@ boost::json::value ast::Module::toJson() {
   };
 }
 
-std::unique_ptr<ast::Module> ast::Module::fromJson(boost::json::value json) {
-  auto name = getJsonValue<ast::Module, std::string>(json, "name");
-  auto imports = fromJsonVector<ast::Module, ast::Import>(json, "imports");
-  auto stmts = fromJsonVector<ast::Module, ast::Stmt>(json, "stmts");
-  return std::make_unique<ast::Module>(ast::Location::json(), name, imports, stmts);
+Module *Module::fromJson(boost::json::value json) {
+  auto name = getJsonValue<Module, std::string>(json, "name");
+  auto imports = fromJsonVector<Module, Import>(json, "imports");
+  auto stmts = fromJsonVector<Module, Stmt>(json, "stmts");
+
+  return new Module(SourceRange::json(), name, imports, stmts);
 }
 
+} // namespace ast
 } // namespace plsm
diff --git a/compiler/src/AST/Stmt/AssignStmt.cpp b/compiler/src/AST/Stmt/AssignStmt.cpp
new file mode 100644
index 0000000..fe3e622
--- /dev/null
+++ b/compiler/src/AST/Stmt/AssignStmt.cpp
@@ -0,0 +1,21 @@
+#include "AST/AST.h"
+
+namespace plsm {
+namespace ast {
+
+boost::json::value AssignStmt::toJson() {
+  return {
+      {"@type", "AssignStmt"},
+      {"lval", lval->toJson()},
+      {"rval", rval->toJson()},
+  };
+}
+
+AssignStmt *AssignStmt::fromJson(boost::json::value json) {
+  auto lval = fromJsonProperty<AssignStmt, Expr>(json, "lval");
+  auto rval = fromJsonProperty<AssignStmt, Expr>(json, "rval");
+  return new AssignStmt(SourceRange::json(), lval, rval);
+}
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/src/AST/Stmt/ExprStmt.cpp b/compiler/src/AST/Stmt/ExprStmt.cpp
index 74d183c..344d8b6 100644
--- a/compiler/src/AST/Stmt/ExprStmt.cpp
+++ b/compiler/src/AST/Stmt/ExprStmt.cpp
@@ -1,16 +1,19 @@
-#include "AST/Stmt/ExprStmt.h"
-#include "AST/Def.h"
+#include "AST/AST.h"
 
 namespace plsm {
+namespace ast {
 
-boost::json::value ast::ExprStmt::toJson() {
-  return {{"@type", "ExprStmt"}, {"expr", expr->toJson()}};
+boost::json::value ExprStmt::toJson() {
+  return {
+      {"@type", "ExprStmt"},
+      {"expr", expr->toJson()},
+  };
 }
 
-std::unique_ptr<ast::ExprStmt>
-ast::ExprStmt::fromJson(boost::json::value json) {
-  auto expr = fromJsonProperty<ast::ExprStmt, ast::Expr>(json, "expr");
-  return std::make_unique<ast::ExprStmt>(ast::Location::json(), expr);
+ExprStmt *ExprStmt::fromJson(boost::json::value json) {
+  auto expr = fromJsonProperty<ExprStmt, Expr>(json, "expr");
+  return new ExprStmt(SourceRange::json(), expr);
 }
 
+} // namespace ast
 } // namespace plsm
diff --git a/compiler/src/AST/Stmt/FnDecl.cpp b/compiler/src/AST/Stmt/FnDecl.cpp
new file mode 100644
index 0000000..7bafb0d
--- /dev/null
+++ b/compiler/src/AST/Stmt/FnDecl.cpp
@@ -0,0 +1,41 @@
+#include "AST/AST.h"
+#include "Utils.h"
+
+namespace plsm {
+namespace ast {
+
+boost::json::value FnParam::toJson() {
+  return {
+      {"@type", "FnParam"},
+      {"name", name},
+      {"typeName", typeName->toJson()},
+  };
+}
+
+FnParam *FnParam::fromJson(boost::json::value json) {
+  auto name = getJsonValue<FnParam, std::string>(json, "name");
+  auto typeName = fromJsonProperty<FnParam, TypeName>(json, "typeName");
+  return new FnParam(SourceRange::json(), name, typeName);
+}
+
+boost::json::value FnDecl::toJson() {
+  return {
+      {"@type", "FnDecl"},
+      {"name", name},
+      {"params", utils::mapToJson(params)},
+      {"returnTypeName", returnTypeName->toJson()},
+      {"body", utils::mapToJson(body)},
+  };
+}
+
+FnDecl *FnDecl::fromJson(boost::json::value json) {
+  auto name = getJsonValue<FnDecl, std::string>(json, "name");
+  auto params = fromJsonVector<FnDecl, FnParam>(json, "params");
+  auto returnTypeName =
+      fromJsonProperty<FnDecl, TypeName>(json, "returnTypeName");
+  auto body = fromJsonVector<FnDecl, Stmt>(json, "body");
+  return new FnDecl(SourceRange::json(), name, params, returnTypeName, body);
+}
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/src/AST/Stmt/FnDef.cpp b/compiler/src/AST/Stmt/FnDef.cpp
deleted file mode 100644
index deea330..0000000
--- a/compiler/src/AST/Stmt/FnDef.cpp
+++ /dev/null
@@ -1,39 +0,0 @@
-#include "AST/Def.h"
-#include "Utils.h"
-
-namespace plsm {
-
-boost::json::value ast::FnArg::toJson() {
-  return {
-      {"@type", "FnArg"},
-      {"name", name},
-      {"type", type->toJson()},
-  };
-}
-
-std::unique_ptr<ast::FnArg> ast::FnArg::fromJson(boost::json::value json) {
-  auto name = getJsonValue<ast::FnArg, std::string>(json, "name");
-  auto type = fromJsonProperty<ast::FnArg, ast::Type>(json, "type");
-  return std::make_unique<ast::FnArg>(ast::Location::json(), name, type);
-}
-
-boost::json::value ast::FnDef::toJson() {
-  return {
-      {"@type", "FnDef"},
-      {"name", name},
-      {"args", utils::mapToJson(args)},
-      {"returnType", returnType->toJson()},
-      {"body", body->toJson()},
-  };
-}
-
-std::unique_ptr<ast::FnDef> ast::FnDef::fromJson(boost::json::value json) {
-  auto name = getJsonValue<ast::FnDef, std::string>(json, "name");
-  auto args = fromJsonVector<ast::FnDef, ast::FnArg>(json, "args");
-  auto returnType = fromJsonProperty<ast::FnDef, ast::Type>(json, "returnType");
-  auto body = fromJsonProperty<ast::FnDef, ast::Expr>(json, "body");
-  return std::make_unique<ast::FnDef>(ast::Location::json(), name, args,
-                                      returnType, body);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Stmt/IfStmt.cpp b/compiler/src/AST/Stmt/IfStmt.cpp
new file mode 100644
index 0000000..261c378
--- /dev/null
+++ b/compiler/src/AST/Stmt/IfStmt.cpp
@@ -0,0 +1,24 @@
+#include "AST/AST.h"
+#include "Utils.h"
+
+namespace plsm {
+namespace ast {
+
+boost::json::value IfStmt::toJson() {
+  return {
+      {"@type", "IfStmt"},
+      {"condition", condition->toJson()},
+      {"ifBody", utils::mapToJson(ifBody)},
+      {"elseBody", utils::mapToJson(elseBody)},
+  };
+}
+
+IfStmt *IfStmt::fromJson(boost::json::value json) {
+  auto condition = fromJsonProperty<IfStmt, Expr>(json, "condition");
+  auto ifBody = fromJsonVector<IfStmt, Stmt>(json, "ifBody");
+  auto elseBody = fromJsonVector<IfStmt, Stmt>(json, "elseBody");
+  return new IfStmt(SourceRange::json(), condition, ifBody, elseBody);
+}
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/src/AST/Stmt/RetStmt.cpp b/compiler/src/AST/Stmt/RetStmt.cpp
new file mode 100644
index 0000000..b262b6a
--- /dev/null
+++ b/compiler/src/AST/Stmt/RetStmt.cpp
@@ -0,0 +1,19 @@
+#include "AST/AST.h"
+
+namespace plsm {
+namespace ast {
+
+boost::json::value RetStmt::toJson() {
+  return {
+      {"@type", "RetStmt"},
+      {"value", value->toJson()},
+  };
+}
+
+RetStmt *RetStmt::fromJson(boost::json::value json) {
+  auto value = fromJsonProperty<RetStmt, Expr>(json, "value");
+  return new RetStmt(SourceRange::json(), value);
+}
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/src/AST/Stmt/TraitAlias.cpp b/compiler/src/AST/Stmt/TraitAlias.cpp
deleted file mode 100644
index 25ee489..0000000
--- a/compiler/src/AST/Stmt/TraitAlias.cpp
+++ /dev/null
@@ -1,22 +0,0 @@
-#include "AST/Stmt/TraitAlias.h"
-#include "AST/Def.h"
-
-namespace plsm {
-
-boost::json::value ast::TraitAlias::toJson() {
-  return {
-      {"@type", "TraitAlias"},
-      {"alias", alias},
-      {"aliased", aliased},
-  };
-}
-
-std::unique_ptr<ast::TraitAlias>
-ast::TraitAlias::fromJson(boost::json::value json) {
-  auto alias = getJsonValue<ast::TraitAlias, std::string>(json, "alias");
-  auto aliased = getJsonValue<ast::TraitAlias, std::string>(json, "aliased");
-  return std::make_unique<ast::TraitAlias>(ast::Location::json(), alias,
-                                           aliased);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Stmt/TraitDef.cpp b/compiler/src/AST/Stmt/TraitDef.cpp
deleted file mode 100644
index fecb378..0000000
--- a/compiler/src/AST/Stmt/TraitDef.cpp
+++ /dev/null
@@ -1,23 +0,0 @@
-#include "AST/Def.h"
-#include "AST/Stmt/FnDef.h"
-#include "AST/Stmt/TraitDef.h"
-#include "Utils.h"
-
-namespace plsm {
-
-boost::json::value ast::TraitDef::toJson() {
-  return {
-      {"@type", "TraitDef"},
-      {"name", name},
-      {"traits", utils::mapToJson(traits)},
-  };
-}
-
-std::unique_ptr<ast::TraitDef>
-ast::TraitDef::fromJson(boost::json::value json) {
-  auto name = getJsonValue<ast::TraitDef, std::string>(json, "name");
-  auto traits = fromJsonVector<ast::TraitDef, ast::FnDef>(json, "traits");
-  return std::make_unique<ast::TraitDef>(ast::Location::json(), name, traits);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Stmt/TypeAlias.cpp b/compiler/src/AST/Stmt/TypeAlias.cpp
deleted file mode 100644
index 45c0a06..0000000
--- a/compiler/src/AST/Stmt/TypeAlias.cpp
+++ /dev/null
@@ -1,18 +0,0 @@
-#include "AST/Def.h"
-
-namespace plsm {
-
-boost::json::value ast::TypeAlias::toJson() {
-  return {
-      {"@type", "TypeAlias"},
-      {"alias", alias},
-      {"type", type->toJson()},
-  };
-}
-
-std::unique_ptr<ast::TypeAlias>
-ast::TypeAlias::fromJson(boost::json::value json) {
-  return nullptr;
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Stmt/TypeDef.cpp b/compiler/src/AST/Stmt/TypeDef.cpp
deleted file mode 100644
index 19f76ef..0000000
--- a/compiler/src/AST/Stmt/TypeDef.cpp
+++ /dev/null
@@ -1,25 +0,0 @@
-#include "AST/Def.h"
-#include "AST/Stmt/FnDef.h"
-#include "AST/Stmt/TypeDef.h"
-#include "Utils.h"
-#include <memory>
-
-namespace plsm {
-
-boost::json::value ast::TypeDef::toJson() {
-  return {
-      {"@type", "TypeDef"},
-      {"name", name},
-      {"attrs", utils::mapToJson(attrs)},
-      {"members", utils::mapToJson(members)},
-  };
-}
-
-std::unique_ptr<ast::TypeDef> ast::TypeDef::fromJson(boost::json::value json) {
-  auto name = getJsonValue<ast::TypeDef, std::string>(json, "name");
-  auto attrs = fromJsonVector<ast::TypeDef, ast::FnArg>(json, "attrs");
-  auto members = fromJsonVector<ast::TypeDef, ast::FnDef>(json, "members");
-  return std::make_unique<ast::TypeDef>(ast::Location::json(), name, attrs, members);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Stmt/ValDecl.cpp b/compiler/src/AST/Stmt/ValDecl.cpp
deleted file mode 100644
index c2b3934..0000000
--- a/compiler/src/AST/Stmt/ValDecl.cpp
+++ /dev/null
@@ -1,21 +0,0 @@
-#include "AST/Def.h"
-
-namespace plsm {
-
-boost::json::value ast::ValDecl::toJson() {
-  return {
-      {"@type", "ValDecl"},
-      {"name", name},
-      {"type", type->toJson()},
-      {"value", value->toJson()},
-  };
-}
-
-std::unique_ptr<ast::ValDecl> ast::ValDecl::fromJson(boost::json::value json) {
-  auto name = getJsonValue<ast::ValDecl, std::string>(json, "name");
-  auto type = fromJsonProperty<ast::ValDecl, ast::Type>(json, "type");
-  auto value = fromJsonProperty<ast::ValDecl, ast::Expr>(json, "value");
-  return std::make_unique<ast::ValDecl>(ast::Location::json(), name, type, value);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Stmt/VarDecl.cpp b/compiler/src/AST/Stmt/VarDecl.cpp
new file mode 100644
index 0000000..22c0d0d
--- /dev/null
+++ b/compiler/src/AST/Stmt/VarDecl.cpp
@@ -0,0 +1,21 @@
+#include "AST/AST.h"
+
+namespace plsm {
+namespace ast {
+
+boost::json::value VarDecl::toJson() {
+  return {
+      {"@type", "VarDecl"},
+      {"name", name},
+      {"typeName", typeName->toJson()},
+  };
+}
+
+VarDecl *VarDecl::fromJson(boost::json::value json) {
+  auto name = getJsonValue<VarDecl, std::string>(json, "name");
+  auto typeName = fromJsonProperty<VarDecl, TypeName>(json, "typeName");
+  return new VarDecl(SourceRange::json(), name, typeName);
+}
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/src/AST/Stmt/WhileStmt.cpp b/compiler/src/AST/Stmt/WhileStmt.cpp
new file mode 100644
index 0000000..e25515b
--- /dev/null
+++ b/compiler/src/AST/Stmt/WhileStmt.cpp
@@ -0,0 +1,22 @@
+#include "AST/AST.h"
+#include "Utils.h"
+
+namespace plsm {
+namespace ast {
+
+boost::json::value WhileStmt::toJson() {
+  return {
+      {"@type", "WhileStmt"},
+      {"condition", condition->toJson()},
+      {"body", utils::mapToJson(body)},
+  };
+}
+
+WhileStmt *WhileStmt::fromJson(boost::json::value json) {
+  auto condition = fromJsonProperty<WhileStmt, Expr>(json, "condition");
+  auto body = fromJsonVector<WhileStmt, Stmt>(json, "body");
+  return new WhileStmt(SourceRange::json(), condition, body);
+}
+
+} // namespace ast
+} // namespace plsm
diff --git a/compiler/src/AST/Type/Closure.cpp b/compiler/src/AST/Type/Closure.cpp
deleted file mode 100644
index 53cf414..0000000
--- a/compiler/src/AST/Type/Closure.cpp
+++ /dev/null
@@ -1,21 +0,0 @@
-#include "AST/Def.h"
-#include "Utils.h"
-
-namespace plsm {
-
-boost::json::value ast::ClosureType::toJson() {
-  return {
-      {"@type", "ClosureType"},
-      {"from", utils::mapToJson(from)},
-      {"to", to->toJson()},
-  };
-}
-
-std::unique_ptr<ast::ClosureType>
-ast::ClosureType::fromJson(boost::json::value json) {
-  auto from = fromJsonVector<ast::ClosureType, ast::Type>(json, "from");
-  auto to = fromJsonProperty<ast::ClosureType, ast::Type>(json, "to");
-  return std::make_unique<ast::ClosureType>(ast::Location::json(), from, to);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Type/FunctionType.cpp b/compiler/src/AST/Type/FunctionType.cpp
new file mode 100644
index 0000000..9c26c39
--- /dev/null
+++ b/compiler/src/AST/Type/FunctionType.cpp
@@ -0,0 +1,22 @@
+#include "AST/AST.h"
+#include "Utils.h"
+
+namespace plsm {
+namespace ast {
+
+boost::json::value FunctionType::toJson() {
+  return {
+      {"@type", "FunctionType"},
+      {"paramTypes", utils::mapToJson(paramTypes)},
+      {"returnType", returnType->toJson()},
+  };
+}
+
+FunctionType *FunctionType::fromJson(boost::json::value json) {
+  auto paramTypes = fromJsonVector<FunctionType, Type>(json, "paramTypes");
+  auto returnType = fromJsonProperty<FunctionType, Type>(json, "returnType");
+  return new FunctionType(paramTypes, returnType);
+}
+
+} // namespace ast
+} // namespace plsm
\ No newline at end of file
diff --git a/compiler/src/AST/Type/Generic.cpp b/compiler/src/AST/Type/Generic.cpp
deleted file mode 100644
index 5b9bd06..0000000
--- a/compiler/src/AST/Type/Generic.cpp
+++ /dev/null
@@ -1,22 +0,0 @@
-#include "AST/Def.h"
-#include "AST/Type/Generic.h"
-#include "Utils.h"
-
-namespace plsm {
-
-boost::json::value ast::GenericType::toJson() {
-  return {
-      {"@type", "GenericType"},
-      {"name", name},
-      {"types", utils::mapToJson(types)},
-  };
-}
-
-std::unique_ptr<ast::GenericType>
-ast::GenericType::fromJson(boost::json::value json) {
-  auto name = getJsonValue<ast::GenericType, std::string>(json, "name");
-  auto types = fromJsonVector<ast::GenericType, ast::Type>(json, "types");
-  return std::make_unique<ast::GenericType>(ast::Location::json(), name, types);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Type/Named.cpp b/compiler/src/AST/Type/Named.cpp
deleted file mode 100644
index 04b57d3..0000000
--- a/compiler/src/AST/Type/Named.cpp
+++ /dev/null
@@ -1,19 +0,0 @@
-#include "AST/Def.h"
-#include "AST/Type/Named.h"
-
-namespace plsm {
-
-boost::json::value ast::NamedType::toJson() {
-  return {
-      {"@type", "NamedType"},
-      {"name", name},
-  };
-}
-
-std::unique_ptr<ast::NamedType>
-ast::NamedType::fromJson(boost::json::value json) {
-  auto name = getJsonValue<ast::NamedType, std::string>(json, "name");
-  return std::make_unique<ast::NamedType>(ast::Location::json(), name);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/Type/PrimitiveType.cpp b/compiler/src/AST/Type/PrimitiveType.cpp
new file mode 100644
index 0000000..9d660bd
--- /dev/null
+++ b/compiler/src/AST/Type/PrimitiveType.cpp
@@ -0,0 +1,19 @@
+#include "AST/AST.h"
+
+namespace plsm {
+namespace ast {
+
+boost::json::value PrimitiveType::toJson() {
+  return {
+      {"@type", "PrimitiveType"},
+      {"name", name},
+  };
+}
+
+PrimitiveType *PrimitiveType::fromJson(boost::json::value json) {
+  auto name = getJsonValue<PrimitiveType, std::string>(json, "name");
+  return new PrimitiveType(name);
+}
+
+} // namespace ast
+} // namespace plsm
\ No newline at end of file
diff --git a/compiler/src/AST/Type/Tuple.cpp b/compiler/src/AST/Type/Tuple.cpp
deleted file mode 100644
index 2d60bb1..0000000
--- a/compiler/src/AST/Type/Tuple.cpp
+++ /dev/null
@@ -1,20 +0,0 @@
-#include "AST/Def.h"
-#include "AST/Type/Tuple.h"
-#include "Utils.h"
-
-namespace plsm {
-
-boost::json::value ast::TupleType::toJson() {
-  return {
-      {"@type", "TupleType"},
-      {"types", utils::mapToJson(types)},
-  };
-}
-
-std::unique_ptr<ast::TupleType>
-ast::TupleType::fromJson(boost::json::value json) {
-  auto types = fromJsonVector<ast::TupleType, ast::Type>(json, "types");
-  return std::make_unique<ast::TupleType>(ast::Location::json(), types);
-}
-
-} // namespace plsm
diff --git a/compiler/src/AST/TypeName/PrimitiveTypeName.cpp b/compiler/src/AST/TypeName/PrimitiveTypeName.cpp
new file mode 100644
index 0000000..da42043
--- /dev/null
+++ b/compiler/src/AST/TypeName/PrimitiveTypeName.cpp
@@ -0,0 +1,16 @@
+#include "AST/AST.h"
+
+namespace plsm {
+namespace ast {
+
+boost::json::value PrimitiveTypeName::toJson() {
+  return {{"@type", "PrimitiveTypeName"}, {"name", name}};
+}
+
+PrimitiveTypeName *PrimitiveTypeName::fromJson(boost::json::value json) {
+  auto name = getJsonValue<PrimitiveTypeName, std::string>(json, "name");
+  return new PrimitiveTypeName(SourceRange::json(), name);
+}
+
+} // namespace ast
+} // namespace plsm
\ No newline at end of file
diff --git a/compiler/src/Parser.cpp b/compiler/src/Parser.cpp
index f0bbf6d..7f85184 100644
--- a/compiler/src/Parser.cpp
+++ b/compiler/src/Parser.cpp
@@ -1,21 +1,16 @@
 #include "Parser.h"
 
-#include "AST/Def.h"
-
-#include <any>
-#include <sstream>
-
-#include "AST/Module/Module.h"
+#include "AST/AST.h"
 #include "plsmBaseVisitor.h"
 #include "plsmLexer.h"
 #include "plsmParser.h"
 
-class ErrorListener : public antlr4::BaseErrorListener {
+class MyAntlr4ErrorListener : public antlr4::BaseErrorListener {
   std::string file;
   std::string *error;
 
 public:
-  ErrorListener(const std::string &file, std::string *error)
+  MyAntlr4ErrorListener(const std::string &file, std::string *error)
       : file(file), error(error) {}
 
   virtual void syntaxError(antlr4::Recognizer *recognizer,
@@ -30,423 +25,7 @@ public:
 
 namespace plsm {
 
-class Visitor : public plsmBaseVisitor {
-private:
-  const std::string file;
-
-public:
-  Visitor(const std::string &file) : file(file) {}
-
-  inline ast::Location loc(antlr4::ParserRuleContext *ctx) {
-    return ast::Location(
-        file,
-        std::pair<size_t, size_t>(ctx->getStart()->getLine(),
-                                  ctx->getStart()->getCharPositionInLine()),
-        std::pair<size_t, size_t>(ctx->getStop()->getLine(),
-                                  ctx->getStop()->getCharPositionInLine()));
-  }
-
-  template <typename T> inline T visitT(antlr4::tree::ParseTree *ctx) {
-    return std::any_cast<T>(visit(ctx));
-  }
-
-  template <typename T>
-  inline std::unique_ptr<T> visitU(antlr4::tree::ParseTree *ctx) {
-    return std::unique_ptr<T>(visitT<T *>(ctx));
-  }
-
-  template <typename T>
-  inline std::vector<std::unique_ptr<T>> visitVU(antlr4::tree::ParseTree *ctx) {
-    std::vector<std::unique_ptr<T>> res;
-    for (auto &el : visitT<std::vector<T *>>(ctx))
-      res.push_back(std::unique_ptr<T>(el));
-    return res;
-  }
-
-  virtual std::any visitModule(plsmParser::ModuleContext *ctx) override {
-    auto name = ctx->identifier()->getText();
-
-    std::vector<std::unique_ptr<ast::Import>> imports;
-    for (auto &import : ctx->moduleImport())
-      imports.push_back(visitU<ast::Import>(import));
-
-    std::vector<std::unique_ptr<ast::Stmt>> stmts;
-    for (auto &stmt : ctx->moduleStmt())
-      stmts.push_back(visitU<ast::Stmt>(stmt));
-
-    return std::any(new ast::Module(loc(ctx), name, imports, stmts));
-  }
-
-  virtual std::any
-  visitModuleImport(plsmParser::ModuleImportContext *ctx) override {
-    return std::any(
-        new ast::Import(loc(ctx), visitT<std::string>(ctx->importName())));
-  }
-
-  virtual std::any
-  visitImportName(plsmParser::ImportNameContext *ctx) override {
-    auto name = ctx->identifier(0)->getText();
-
-    for (size_t i = 1; i < ctx->identifier().size(); i++)
-      name = name + "/" + ctx->identifier(i)->getText();
-
-    return std::any(name);
-  }
-
-  virtual std::any
-  visitModuleStmt(plsmParser::ModuleStmtContext *ctx) override {
-    ast::Stmt *stmt;
-
-    if (ctx->let())
-      stmt = (ast::Stmt *)visitT<ast::ValDecl *>(ctx->let());
-    if (ctx->fnDecl())
-      stmt = (ast::Stmt *)visitT<ast::FnDef *>(ctx->fnDecl());
-    if (ctx->fnDef())
-      stmt = (ast::Stmt *)visitT<ast::FnDef *>(ctx->fnDef());
-    if (ctx->traitDef())
-      stmt = (ast::Stmt *)visitT<ast::Stmt *>(ctx->traitDef());
-    if (ctx->typeDef())
-      stmt = (ast::Stmt *)visitT<ast::Stmt *>(ctx->typeDef());
-
-    return std::any(stmt);
-  }
-
-  virtual std::any visitTraitDef(plsmParser::TraitDefContext *ctx) override {
-    auto name = ctx->identifier(0)->getText();
-
-    if (ctx->identifier(1)) {
-      auto aliased = ctx->identifier(1)->getText();
-      return std::any(
-          (ast::Stmt *)new ast::TraitAlias(loc(ctx), name, aliased));
-    }
-
-    std::vector<std::unique_ptr<ast::FnDef>> fns;
-    for (auto &decl : ctx->fnDecl())
-      fns.push_back(visitU<ast::FnDef>(decl));
-
-    return std::any((ast::Stmt *)new ast::TraitDef(loc(ctx), name, fns));
-  }
-
-  virtual std::any visitTypeDef(plsmParser::TypeDefContext *ctx) override {
-    auto name = ctx->identifier()->getText();
-
-    if (ctx->type()) {
-      auto gen = visitU<ast::Type>(ctx->type());
-      return std::any((ast::Stmt *)new ast::TypeAlias(loc(ctx), name, gen));
-    }
-
-    std::vector<std::unique_ptr<ast::FnArg>> attrs;
-    if (ctx->fnDefArgs())
-      attrs = visitVU<ast::FnArg>(ctx->fnDefArgs());
-
-    std::vector<std::unique_ptr<ast::FnDef>> members;
-    for (auto &def : ctx->fnDef())
-      members.push_back(visitU<ast::FnDef>(def));
-    for (auto &decl : ctx->fnDecl())
-      members.push_back(visitU<ast::FnDef>(decl));
-
-    return std::any(
-        (ast::Stmt *)new ast::TypeDef(loc(ctx), name, attrs, members));
-  }
-
-  virtual std::any visitFnDef(plsmParser::FnDefContext *ctx) override {
-    auto name = ctx->identifier()->getText();
-
-    std::vector<std::unique_ptr<ast::FnArg>> args;
-    if (ctx->fnDefArgs())
-      args = std::move(visitVU<ast::FnArg>(ctx->fnDefArgs()));
-
-    auto returnType = visitU<ast::Type>(ctx->type());
-    auto body = visitU<ast::Expr>(ctx->expr());
-
-    return std::any(new ast::FnDef(loc(ctx), name, args, returnType, body));
-  }
-
-  virtual std::any visitFnDefArgs(plsmParser::FnDefArgsContext *ctx) override {
-    std::vector<ast::FnArg *> args;
-
-    for (size_t i = 0; i < ctx->children.size(); i += 3) {
-      auto name = ctx->children[i]->getText();
-      auto type = visitU<ast::Type>(ctx->children[i + 1]);
-      args.push_back(new ast::FnArg(loc(ctx), name, type));
-    }
-
-    return std::any(args);
-  }
-
-  virtual std::any visitFnDecl(plsmParser::FnDeclContext *ctx) override {
-    auto name = ctx->identifier()->getText();
-
-    std::vector<std::unique_ptr<ast::FnArg>> args;
-    if (ctx->fnDeclArgs())
-      args = visitVU<ast::FnArg>(ctx->fnDeclArgs());
-
-    auto returnType = visitU<ast::Type>(ctx->type());
-    auto body = std::unique_ptr<ast::Expr>(nullptr);
-
-    return std::any(new ast::FnDef(loc(ctx), name, args, returnType, body));
-  }
-
-  virtual std::any
-  visitFnDeclArgs(plsmParser::FnDeclArgsContext *ctx) override {
-    std::vector<ast::FnArg *> args;
-
-    for (size_t i = 0; i < ctx->children.size(); i++) {
-      std::string name;
-      if (dynamic_cast<plsmParser::IdentifierContext *>(ctx->children[i]))
-        name = ctx->children[i++]->getText();
-
-      auto type = visitU<ast::Type>(ctx->children[i++]);
-
-      args.push_back(new ast::FnArg(loc(ctx), name, type));
-    }
-
-    return std::any(args);
-  }
-
-  virtual std::any visitLet(plsmParser::LetContext *ctx) override {
-    auto name = ctx->identifier()->getText();
-
-    std::unique_ptr<ast::Type> type(nullptr);
-    if (ctx->type())
-      type = visitU<ast::Type>(ctx->type());
-
-    auto expr = visitU<ast::Expr>(ctx->expr());
-
-    return std::any(new ast::ValDecl(loc(ctx), name, type, expr));
-  }
-
-  virtual std::any visitExprStmt(plsmParser::ExprStmtContext *ctx) override {
-    auto expr = visitU<ast::Expr>(ctx->expr());
-    return std::any(new ast::ExprStmt(loc(ctx), expr));
-  }
-
-  virtual std::any visitType1(plsmParser::Type1Context *ctx) override {
-    if (ctx->type0())
-      return visit(ctx->type0());
-
-    if (ctx->children[0]->getText() == "(") {
-      if (ctx->type())
-        return visit(ctx->type());
-
-      if (ctx->tupleTypeList()) {
-        auto types = visitVU<ast::Type>(ctx->tupleTypeList());
-        return std::any((ast::Type *)new ast::TupleType(loc(ctx), types));
-      }
-    }
-
-    if (ctx->children[0]->getText() == "[") {
-      std::vector<std::unique_ptr<ast::Type>> args;
-      if (ctx->typeList())
-        args = visitVU<ast::Type>(ctx->typeList());
-
-      auto returnType = visitU<ast::Type>(ctx->type());
-
-      return std::any(
-          (ast::Type *)new ast::ClosureType(loc(ctx), args, returnType));
-    }
-
-    throw std::logic_error("type2 not implemented");
-  }
-
-  virtual std::any visitType0(plsmParser::Type0Context *ctx) override {
-    auto name = ctx->identifier()->getText();
-
-    if (ctx->typeList()) {
-      auto types = visitVU<ast::Type>(ctx->typeList());
-      return std::any((ast::Type *)new ast::GenericType(loc(ctx), name, types));
-    }
-
-    return std::any((ast::Type *)new ast::NamedType(loc(ctx), name));
-  }
-
-  virtual std::any
-  visitTupleTypeList(plsmParser::TupleTypeListContext *ctx) override {
-    std::vector<ast::Type *> types;
-    for (auto &type : ctx->type())
-      types.push_back(visitT<ast::Type *>(type));
-
-    return std::any(types);
-  }
-
-  virtual std::any visitTypeList(plsmParser::TypeListContext *ctx) override {
-    std::vector<ast::Type *> types;
-    for (auto &type : ctx->type())
-      types.push_back(visitT<ast::Type *>(type));
-
-    return std::any(types);
-  }
-
-  virtual std::any visitExpr3(plsmParser::Expr3Context *ctx) override {
-    if (ctx->expr2())
-      return visit(ctx->expr2());
-
-    // closure
-    if (ctx->children[0]->getText() == "[") {
-      std::vector<std::unique_ptr<ast::FnArg>> args;
-      if (ctx->fnDefArgs())
-        args = visitVU<ast::FnArg>(ctx->fnDefArgs());
-
-      auto body = visitU<ast::Expr>(ctx->expr());
-
-      return std::any((ast::Expr *)new ast::Closure(loc(ctx), args, body));
-    }
-
-    // block
-    if (ctx->children[0]->getText() == "{") {
-      std::vector<std::unique_ptr<ast::Stmt>> stmts;
-      for (auto &stmt : ctx->blockStmt())
-        stmts.push_back(visitU<ast::Stmt>(stmt));
-
-      auto result = visitU<ast::Expr>(ctx->expr());
-
-      return std::any((ast::Expr *)new ast::BlockExpr(loc(ctx), stmts, result));
-    }
-
-    throw std::logic_error("expr3 not implemented");
-  }
-
-  virtual std::any visitExpr2(plsmParser::Expr2Context *ctx) override {
-    if (ctx->expr2()) {
-      auto left = visitU<ast::Expr>(ctx->expr2());
-      auto op = ctx->operator_()->getText();
-      auto right = visitU<ast::Expr>(ctx->expr1());
-      return std::any((ast::Expr *)new ast::BinExpr(loc(ctx), left, op, right));
-    }
-
-    return visit(ctx->expr1());
-  }
-
-  virtual std::any visitExpr1(plsmParser::Expr1Context *ctx) override {
-    if (ctx->operator_()) {
-      auto op = ctx->operator_()->getText();
-      auto expr = visitU<ast::Expr>(ctx->expr0());
-      return std::any((ast::Expr *)new ast::UnaryExpr(loc(ctx), op, expr));
-    }
-
-    return visit(ctx->expr0());
-  }
-
-  virtual std::any visitExpr0(plsmParser::Expr0Context *ctx) override {
-    if (ctx->literal())
-      return visit(ctx->literal());
-
-    if (ctx->expr()) {
-      auto expr = visitU<ast::Expr>(ctx->expr());
-      return std::any((ast::Expr *)new ast::PrefExpr(loc(ctx), expr));
-    }
-
-    if (ctx->expr0()) {
-      auto expr = visitU<ast::Expr>(ctx->expr0());
-
-      // property accessor
-      if (ctx->identifier()) {
-        auto name = ctx->identifier()->getText();
-        return std::any((ast::Expr *)new ast::PropExpr(loc(ctx), expr, name));
-      }
-
-      // function/closure call
-      std::vector<std::unique_ptr<ast::Expr>> args;
-      if (ctx->exprList())
-        args = visitVU<ast::Expr>(ctx->exprList());
-
-      return std::any((ast::Expr *)new ast::CallExpr(loc(ctx), expr, args));
-    }
-
-    // tuple
-    if (ctx->tupleExprList()) {
-      auto values = visitVU<ast::Expr>(ctx->tupleExprList());
-      return std::any((ast::Expr *)new ast::Tuple(loc(ctx), values));
-    }
-
-    // identifier
-    if (ctx->identifier()) {
-      auto name = ctx->identifier()->getText();
-      return std::any((ast::Expr *)new ast::Identifier(loc(ctx), name));
-    }
-
-    throw std::logic_error("expr0 not implemented");
-  }
-
-  virtual std::any visitBlockStmt(plsmParser::BlockStmtContext *ctx) override {
-    ast::Stmt *stmt;
-
-    if (ctx->let())
-      stmt = (ast::Stmt *)visitT<ast::ValDecl *>(ctx->let());
-    if (ctx->exprStmt())
-      stmt = (ast::Stmt *)visitT<ast::ExprStmt *>(ctx->exprStmt());
-    if (ctx->fnDef())
-      stmt = (ast::Stmt *)visitT<ast::FnDef *>(ctx->fnDef());
-
-    return std::any(stmt);
-  }
-
-  virtual std::any
-  visitTupleExprList(plsmParser::TupleExprListContext *ctx) override {
-    std::vector<ast::Expr *> exprs;
-    for (auto &expr : ctx->expr())
-      exprs.push_back(visitT<ast::Expr *>(expr));
-
-    return std::any(exprs);
-  }
-
-  virtual std::any visitExprList(plsmParser::ExprListContext *ctx) override {
-    std::vector<ast::Expr *> exprs;
-    for (auto &expr : ctx->expr())
-      exprs.push_back(visitT<ast::Expr *>(expr));
-
-    return std::any(exprs);
-  }
-
-  virtual std::any
-  visitIdentifierList(plsmParser::IdentifierListContext *ctx) override {
-    std::vector<std::string> identifiers;
-    for (auto &identifier : ctx->identifier())
-      identifiers.push_back(visitT<std::string>(identifier));
-
-    return std::any(identifiers);
-  }
-
-  virtual std::any visitLiteral(plsmParser::LiteralContext *ctx) override {
-    if (ctx->NULL_)
-      return std::any((ast::Expr *)new ast::NullValue(loc(ctx)));
-
-    if (ctx->INT_LIT()) {
-      auto text = ctx->INT_LIT()->getText();
-
-      int64_t value;
-
-      if (!text.rfind("0x", 0))
-        value = std::strtol(text.substr(2).data(), NULL, 16);
-
-      else if (!text.rfind("0o", 0))
-        value = std::strtol(text.substr(2).data(), NULL, 8);
-
-      else if (!text.rfind("0b", 0))
-        value = std::strtol(text.substr(2).data(), NULL, 2);
-
-      else value = std::strtol(text.data(), NULL, 10);
-
-      return std::any((ast::Expr *)new ast::IntValue(loc(ctx), value));
-    }
-
-    if (ctx->FLOAT_LIT()) {
-      auto text = ctx->FLOAT_LIT()->getText();
-
-      if (text.at(text.size() - 1) == '.')
-        text += "0";
-      if (text.at(0) == '0')
-        text = "0" + text;
-
-      double value = std::strtod(text.data(), NULL);
-      return std::any((ast::Expr *)new ast::FloatValue(loc(ctx), value));
-    }
-
-    throw std::logic_error("literal not implemented");
-  }
-};
-
-std::unique_ptr<ast::Module> parse(const std::string &file,
+std::shared_ptr<ast::Module> parse(const std::string &file,
                                    const std::string &input) {
   auto istream = antlr4::ANTLRInputStream(input);
   auto lexer = plsmLexer(&istream);
@@ -454,17 +33,12 @@ std::unique_ptr<ast::Module> parse(const std::string &file,
   auto parser = plsmParser(&tokens);
 
   std::string error;
-  ErrorListener listener(file, &error);
+  MyAntlr4ErrorListener listener(file, &error);
   parser.removeErrorListeners();
   parser.addErrorListener(&listener);
 
   auto tree = parser.module();
-
-  if (error.size())
-    throw std::runtime_error(error);
-
-  auto module = std::any_cast<ast::Module *>(Visitor(file).visitModule(tree));
-  return std::unique_ptr<ast::Module>(module);
+  return std::shared_ptr<Module>(tree->ast);
 }
 
 } // namespace plsm
diff --git a/compiler/src/main.cpp b/compiler/src/main.cpp
index 2fd99da..b2d4f45 100644
--- a/compiler/src/main.cpp
+++ b/compiler/src/main.cpp
@@ -1,12 +1,11 @@
-#include <iostream>
 #include <fstream>
+#include <iostream>
 #include <istream>
 #include <sstream>
 
 #include "Parser.h"
 
-static std::string readFile(const std::string &path)
-{
+static std::string readFile(const std::string &path) {
   std::ifstream f(path);
   auto data = (std::stringstream() << f.rdbuf()).str();
   f.close();
@@ -14,10 +13,8 @@ static std::string readFile(const std::string &path)
   return data;
 }
 
-int main(int argc, char *argv[])
-{
-  if (argc != 2)
-  {
+int main(int argc, char *argv[]) {
+  if (argc != 2) {
     std::cout << "Usage:" << std::endl
               << "\t" << argv[0] << " <path/to/file>" << std::endl;
     exit(EXIT_FAILURE);
@@ -25,19 +22,17 @@ int main(int argc, char *argv[])
 
   auto input = readFile(argv[1]);
 
-  std::cout << input << std::endl;
+  // std::cout << input << std::endl;
 
-  try
-  {
+  try {
     auto module = plsm::parse(argv[1], input);
     std::cout << module->toJsonString() << std::endl;
 
-    std::cout << "\n\n";
+    // std::cout << "\n\n";
 
-    std::cout << plsm::ast::Module::fromJson(module->toJson())->toJson() << std::endl;
-  }
-  catch (std::runtime_error &err)
-  {
+    // std::cout << plsm::ast::Module::fromJson(module->toJson())->toJson() <<
+    // std::endl;
+  } catch (std::runtime_error &err) {
     std::cerr << err.what() << std::endl;
     exit(EXIT_FAILURE);
   }
diff --git a/compiler/test.json b/compiler/test.json
new file mode 100644
index 0000000..afd7649
--- /dev/null
+++ b/compiler/test.json
@@ -0,0 +1,142 @@
+{
+  "@type": "Module",
+  "name": "default",
+  "imports": [],
+  "stmts": [
+    {
+      "@type": "FnDecl",
+      "name": "main",
+      "params": [],
+      "returnTypeName": {
+        "@type": "PrimitiveTypeName",
+        "name": "i64"
+      },
+      "body": [
+        {
+          "@type": "VarDecl",
+          "name": "asdf",
+          "typeName": {
+            "@type": "PrimitiveTypeName",
+            "name": "int"
+          }
+        },
+        {
+          "@type": "AssignStmt",
+          "lval": {
+            "@type": "Identifier",
+            "name": "asdf"
+          },
+          "rval": 100
+        },
+        {
+          "@type": "IfStmt",
+          "condition": {
+            "@type": "BinExpr",
+            "op": ">",
+            "lhs": {
+              "@type": "Identifier",
+              "name": "asdf"
+            },
+            "rhs": 1000
+          },
+          "ifBody": [
+            {
+              "@type": "AssignStmt",
+              "lval": {
+                "@type": "Identifier",
+                "name": "a"
+              },
+              "rval": 1
+            }
+          ],
+          "elseBody": [
+            {
+              "@type": "IfStmt",
+              "condition": {
+                "@type": "BinExpr",
+                "op": ">",
+                "lhs": {
+                  "@type": "Identifier",
+                  "name": "asdf"
+                },
+                "rhs": 500
+              },
+              "ifBody": [
+                {
+                  "@type": "AssignStmt",
+                  "lval": {
+                    "@type": "Identifier",
+                    "name": "a"
+                  },
+                  "rval": 2
+                }
+              ],
+              "elseBody": [
+                {
+                  "@type": "AssignStmt",
+                  "lval": {
+                    "@type": "Identifier",
+                    "name": "a"
+                  },
+                  "rval": 3
+                }
+              ]
+            }
+          ]
+        },
+        {
+          "@type": "WhileStmt",
+          "condition": {
+            "@type": "BinExpr",
+            "op": "<",
+            "lhs": {
+              "@type": "Identifier",
+              "name": "a"
+            },
+            "rhs": 10
+          },
+          "body": [
+            {
+              "@type": "AssignStmt",
+              "lval": {
+                "@type": "Identifier",
+                "name": "a"
+              },
+              "rval": {
+                "@type": "Identifier",
+                "name": "a"
+              }
+            },
+            {
+              "@type": "ExprStmt",
+              "expr": {
+                "@type": "UnExpr",
+                "op": "+",
+                "expr": 1
+              }
+            }
+          ]
+        },
+        {
+          "@type": "RetStmt",
+          "value": {
+            "@type": "BinExpr",
+            "op": "+",
+            "lhs": {
+              "@type": "BinExpr",
+              "op": "*",
+              "lhs": 3,
+              "rhs": 10
+            },
+            "rhs": {
+              "@type": "BinExpr",
+              "op": "*",
+              "lhs": 21,
+              "rhs": 2
+            }
+          }
+        }
+      ]
+    }
+  ]
+}
\ No newline at end of file
diff --git a/examples/new.plsm b/examples/new.plsm
new file mode 100644
index 0000000..dffb258
--- /dev/null
+++ b/examples/new.plsm
@@ -0,0 +1,18 @@
+fun main() i64 {
+  var asdf : int;
+  asdf = 100;
+
+  if (asdf > 1000) {
+    a = 1;
+  } else if (asdf > 500) {
+    a = 2;
+  } else {
+    a = 3;
+  }
+
+  while (a < 10) {
+    a = a + 1;
+  }
+
+  ret 3 * 10 + 21.0 * 2;
+}