diff --git a/.vscode/settings.json b/.vscode/settings.json
index 2f9bd90..f2a4425 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -83,6 +83,7 @@
     "set": "cpp",
     "unordered_set": "cpp",
     "source_location": "cpp",
-    "shared_mutex": "cpp"
+    "shared_mutex": "cpp",
+    "strstream": "cpp"
   },
 }
\ No newline at end of file
diff --git a/compiler/include/AST.h b/compiler/include/AST.h
deleted file mode 100644
index ec6162a..0000000
--- a/compiler/include/AST.h
+++ /dev/null
@@ -1,142 +0,0 @@
-#pragma once
-
-#include <string>
-#include <vector>
-
-class Expr;
-class Type;
-
-typedef std::pair<std::string, Type *> FnArg;
-
-class ASTNode
-{
-};
-
-class Stmt : public ASTNode
-{
-};
-
-class Module : public ASTNode
-{
-public:
-  Module(const std::vector<Stmt *> &stmts) : stmts(std::move(stmts)) {}
-  const std::vector<Stmt *> stmts;
-};
-
-class ValDecl : public Stmt
-{
-public:
-  ValDecl(const std::string &name, const Type *type, const Expr *value)
-      : name(name), type(type), value(value) {}
-
-  const std::string name;
-  const Type *type;
-  const Expr *value;
-};
-
-class FnDecl : public Stmt
-{
-public:
-  FnDecl(const std::string &name, const std::vector<FnArg> &args, const Type *returnType, const Expr *body)
-      : name(name), args(std::move(args)), returnType(returnType), body(body) {}
-
-  const std::string name;
-  const std::vector<FnArg> args;
-  const Type *returnType;
-  const Expr *body;
-};
-
-class Type : public ASTNode
-{
-};
-
-class TupleType : public Type
-{
-public:
-  TupleType(const std::vector<Type *> &types) : types(types) {}
-  const std::vector<Type *> types;
-};
-
-class FunctionType : public Type
-{
-public:
-  FunctionType(const std::vector<Type *> &from, const Type *to)
-      : from(std::move(from)), to(to) {}
-
-  const std::vector<Type *> from;
-  const Type *to;
-};
-
-class NamedType : public Type
-{
-public:
-  NamedType(const std::string &name) : name(name) {}
-  const std::string name;
-};
-
-class Expr : public ASTNode
-{
-};
-
-class CallExpr : public Expr
-{
-public:
-  CallExpr(const Expr *callee, const std::vector<Expr *> &args)
-      : callee(callee), args(std::move(args)) {}
-
-  const Expr *callee;
-  const std::vector<Expr *> args;
-};
-
-class UnaryExpr : public Expr
-{
-public:
-  UnaryExpr(const std::string &op, const Expr *expr)
-      : op(op), expr(expr) {}
-
-  const std::string op;
-  const Expr *expr;
-};
-
-class BinExpr : public Expr
-{
-public:
-  BinExpr(const Expr *left, const std::string &op, const Expr *right)
-      : left(left), op(op), right(right) {}
-
-  const Expr *left;
-  const std::string op;
-  const Expr *right;
-};
-
-class PrefExpr : public Expr
-{
-public:
-  PrefExpr(const Expr *expr) : expr(expr) {}
-
-  const Expr *expr;
-};
-
-class Identifier : public Expr
-{
-public:
-  Identifier(const std::string &name) : name(name) {}
-
-  const std::string name;
-};
-
-class IntValue : public Expr
-{
-public:
-  IntValue(const long value) : value(value) {}
-
-  const long value;
-};
-
-class FloatValue : public Expr
-{
-public:
-  FloatValue(const double value) : value(value) {}
-
-  const double value;
-};
diff --git a/compiler/include/AST/Base.h b/compiler/include/AST/Base.h
new file mode 100644
index 0000000..d70fa28
--- /dev/null
+++ b/compiler/include/AST/Base.h
@@ -0,0 +1,22 @@
+#pragma once
+
+namespace ast
+{
+  class ASTNode
+  {
+  public:
+    virtual ~ASTNode() = default;
+  };
+
+  class Expr : public ASTNode
+  {
+  };
+
+  class Stmt : public ASTNode
+  {
+  };
+
+  class Type : public ASTNode
+  {
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Def.h b/compiler/include/AST/Def.h
new file mode 100644
index 0000000..23f9c3f
--- /dev/null
+++ b/compiler/include/AST/Def.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include "Base.h"
+
+#include "Expr/BinExpr.h"
+#include "Expr/Block.h"
+#include "Expr/Call.h"
+#include "Expr/Identifier.h"
+#include "Expr/UnaryExpr.h"
+#include "Expr/Value.h"
+
+#include "Stmt/ExprStmt.h"
+#include "Stmt/FnDecl.h"
+#include "Stmt/ValDecl.h"
+
+#include "Type/Function.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
new file mode 100644
index 0000000..8709b3b
--- /dev/null
+++ b/compiler/include/AST/Expr/BinExpr.h
@@ -0,0 +1,34 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <string>
+
+namespace ast
+{
+  class BinExpr : public Expr
+  {
+  public:
+    BinExpr(const Expr *left, const std::string &op, const Expr *right)
+        : left(left), op(op), right(right) {}
+
+    ~BinExpr()
+    {
+      delete left;
+      delete right;
+    }
+
+    const Expr *left;
+    const std::string op;
+    const Expr *right;
+  };
+
+  class PrefExpr : public Expr
+  {
+  public:
+    PrefExpr(const Expr *expr) : expr(expr) {}
+
+    ~PrefExpr() { delete expr; }
+
+    const Expr *expr;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Expr/Block.h b/compiler/include/AST/Expr/Block.h
new file mode 100644
index 0000000..e9301ce
--- /dev/null
+++ b/compiler/include/AST/Expr/Block.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <vector>
+
+namespace ast
+{
+  class BlockExpr : public Expr
+  {
+  public:
+    BlockExpr(const std::vector<Stmt *> &stmts) : stmts(std::move(stmts)) {}
+    ~BlockExpr()
+    {
+      for (auto &stmt : stmts)
+        delete stmt;
+    }
+
+    const std::vector<Stmt *> stmts;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Expr/Call.h b/compiler/include/AST/Expr/Call.h
new file mode 100644
index 0000000..1f4a833
--- /dev/null
+++ b/compiler/include/AST/Expr/Call.h
@@ -0,0 +1,23 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <vector>
+
+namespace ast
+{
+  class CallExpr : public Expr
+  {
+  public:
+    CallExpr(const Expr *callee, const std::vector<Expr *> &args)
+        : callee(callee), args(std::move(args)) {}
+
+    ~CallExpr()
+    {
+      for (auto &arg : args)
+        delete arg;
+    }
+
+    const Expr *callee;
+    const std::vector<Expr *> args;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Expr/Identifier.h b/compiler/include/AST/Expr/Identifier.h
new file mode 100644
index 0000000..9e36232
--- /dev/null
+++ b/compiler/include/AST/Expr/Identifier.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <string>
+
+namespace ast
+{
+  class Identifier : public Expr
+  {
+  public:
+    Identifier(const std::string &name) : name(name) {}
+
+    const std::string name;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Expr/UnaryExpr.h b/compiler/include/AST/Expr/UnaryExpr.h
new file mode 100644
index 0000000..2e0b2da
--- /dev/null
+++ b/compiler/include/AST/Expr/UnaryExpr.h
@@ -0,0 +1,19 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <string>
+
+namespace ast
+{
+  class UnaryExpr : public Expr
+  {
+  public:
+    UnaryExpr(const std::string &op, const Expr *expr)
+        : op(op), expr(expr) {}
+
+    ~UnaryExpr() { delete expr; }
+
+    const std::string op;
+    const Expr *expr;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Expr/Value.h b/compiler/include/AST/Expr/Value.h
new file mode 100644
index 0000000..475f2f6
--- /dev/null
+++ b/compiler/include/AST/Expr/Value.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <cstdint>
+
+namespace ast
+{
+  class IntValue : public Expr
+  {
+  public:
+    IntValue(int64_t value) : value(value) {}
+    const int64_t value;
+  };
+
+  class FloatValue : public Expr
+  {
+  public:
+    FloatValue(double value) : value(value) {}
+    const double value;
+  };
+}
diff --git a/compiler/include/AST/Module/Import.h b/compiler/include/AST/Module/Import.h
new file mode 100644
index 0000000..ec7ef29
--- /dev/null
+++ b/compiler/include/AST/Module/Import.h
@@ -0,0 +1,14 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <string>
+
+namespace ast
+{
+  class Import : public ASTNode
+  {
+  public:
+    Import(const std::string &moduleName) : moduleName(moduleName) {}
+    const std::string moduleName;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Module/Module.h b/compiler/include/AST/Module/Module.h
new file mode 100644
index 0000000..a25a242
--- /dev/null
+++ b/compiler/include/AST/Module/Module.h
@@ -0,0 +1,28 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <vector>
+
+namespace ast
+{
+  class Import;
+
+  class Module : public ASTNode
+  {
+  public:
+    Module(const std::vector<Import *> &imports, const std::vector<Stmt *> &stmts)
+        : imports(std::move(imports)), stmts(std::move(stmts)) {}
+
+    ~Module()
+    {
+      for (auto &import : imports)
+        delete import;
+
+      for (auto &stmt : stmts)
+        delete stmt;
+    }
+
+    const std::vector<Import *> &imports;
+    const std::vector<Stmt *> stmts;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Stmt/ExprStmt.h b/compiler/include/AST/Stmt/ExprStmt.h
new file mode 100644
index 0000000..a51e5ad
--- /dev/null
+++ b/compiler/include/AST/Stmt/ExprStmt.h
@@ -0,0 +1,15 @@
+#pragma once
+
+#include "AST/Base.h"
+
+namespace ast
+{
+  class ExprStmt : public Stmt
+  {
+  public:
+    ExprStmt(const Expr *expr) : expr(expr) {}
+    ~ExprStmt() { delete expr; }
+
+    const Expr *expr;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Stmt/FnDecl.h b/compiler/include/AST/Stmt/FnDecl.h
new file mode 100644
index 0000000..58eff36
--- /dev/null
+++ b/compiler/include/AST/Stmt/FnDecl.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <vector>
+#include <string>
+
+namespace ast
+{
+  typedef std::pair<std::string, Type *> FnArg;
+
+  class FnDecl : public Stmt
+  {
+  public:
+    FnDecl(const std::string &name, const std::vector<FnArg> &args, const Type *returnType, const Expr *body)
+        : name(name), args(std::move(args)), returnType(returnType), body(body) {}
+
+    ~FnDecl()
+    {
+      for (auto &arg : args)
+        delete arg.second;
+
+      delete returnType;
+      delete body;
+    }
+
+    const std::string name;
+    const std::vector<FnArg> args;
+    const Type *returnType;
+    const Expr *body;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Stmt/ValDecl.h b/compiler/include/AST/Stmt/ValDecl.h
new file mode 100644
index 0000000..783423e
--- /dev/null
+++ b/compiler/include/AST/Stmt/ValDecl.h
@@ -0,0 +1,24 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <string>
+
+namespace ast
+{
+  class ValDecl : public Stmt
+  {
+  public:
+    ValDecl(const std::string &name, const Type *type, const Expr *value)
+        : name(name), type(type), value(value) {}
+
+    ~ValDecl()
+    {
+      delete type;
+      delete value;
+    }
+
+    const std::string name;
+    const Type *type;
+    const Expr *value;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Type/Function.h b/compiler/include/AST/Type/Function.h
new file mode 100644
index 0000000..f1a07b6
--- /dev/null
+++ b/compiler/include/AST/Type/Function.h
@@ -0,0 +1,25 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <vector>
+
+namespace ast
+{
+  class FunctionType : public Type
+  {
+  public:
+    FunctionType(const std::vector<Type *> &from, const Type *to)
+        : from(std::move(from)), to(to) {}
+
+    ~FunctionType()
+    {
+      for (auto &arg : from)
+        delete arg;
+
+      delete to;
+    }
+
+    const std::vector<Type *> from;
+    const Type *to;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Type/Named.h b/compiler/include/AST/Type/Named.h
new file mode 100644
index 0000000..4b6799b
--- /dev/null
+++ b/compiler/include/AST/Type/Named.h
@@ -0,0 +1,14 @@
+#pragma once
+
+#include "AST/Base.h"
+#include <string>
+
+namespace ast
+{
+  class NamedType : public Type
+  {
+  public:
+    NamedType(const std::string &name) : name(name) {}
+    const std::string name;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/AST/Type/Tuple.h b/compiler/include/AST/Type/Tuple.h
new file mode 100644
index 0000000..56c6463
--- /dev/null
+++ b/compiler/include/AST/Type/Tuple.h
@@ -0,0 +1,21 @@
+#pragma once
+
+#include "AST/Def.h"
+#include <vector>
+
+namespace ast
+{
+  class TupleType : public Type
+  {
+  public:
+    TupleType(const std::vector<Type *> &types) : types(std::move(types)) {}
+
+    ~TupleType()
+    {
+      for (auto &type : types)
+        delete type;
+    }
+
+    const std::vector<Type *> types;
+  };
+}
\ No newline at end of file
diff --git a/compiler/include/ASTVisitor.h b/compiler/include/ASTVisitor.h
deleted file mode 100644
index 870f272..0000000
--- a/compiler/include/ASTVisitor.h
+++ /dev/null
@@ -1,22 +0,0 @@
-#pragma once
-
-#include <stdexcept>
-
-#include "AST.h"
-
-template <typename T>
-class ASTVisitor
-{
-  virtual T visit(const ASTNode *node)
-  {
-    if (IntValue *cnode = dynamic_cast<IntValue *>(node))
-      return visitIntValue(cnode);
-    else if (FloatValue *cnode = dynamic_cast<FloatValue *>(node))
-      return visitFloatValue(cnode);
-
-    throw std::logic_error("not implemented");
-  }
-
-  virtual T visitIntValue(const IntValue *node);
-  virtual T visitFloatValue(const IntValue *node);
-};
diff --git a/compiler/include/ParserDriver.h b/compiler/include/ParserDriver.h
index 454c1ce..4ee54f8 100644
--- a/compiler/include/ParserDriver.h
+++ b/compiler/include/ParserDriver.h
@@ -2,13 +2,14 @@
 
 #include <string>
 
-#include "AST.h"
+#include "AST/Def.h"
 #include "parser.gen.h"
 
 class ParserDriver
 {
 public:
   ParserDriver() {}
+  ~ParserDriver() { delete module; }
 
   int parse(const std::string &input);
 
@@ -17,7 +18,7 @@ public:
 
   std::string file;
   yy::location location;
-  Module *module;
+  ast::Module *module;
 };
 
 #define YY_DECL yy::parser::symbol_type yylex(ParserDriver &driver)
diff --git a/compiler/lexer.ll b/compiler/lexer.ll
index 7e3b985..16633e9 100644
--- a/compiler/lexer.ll
+++ b/compiler/lexer.ll
@@ -35,19 +35,24 @@ whitespace  [ \n\t\r\v]+
                 if (text == "->") return _token(RARR);
                 return _token(OPERATOR); }
 
+"."           { return _token(DOT); }
 ","           { return _token(COMMA); }
 ";"           { return _token(SEMI); }
 "("           { return _token(LPAREN); }
 ")"           { return _token(RPAREN); }
 "["           { return _token(LBRACKET); }
 "]"           { return _token(RBRACKET); }
+"{"           { return _token(LBRACE); }
+"}"           { return _token(RBRACE); }
 
-"fn"          { return _token(FN); }
-"unop"        { return _token(UNOP); }
 "binop"       { return _token(BINOP); }
-"val"         { return _token(VAL); }
-"import"      { return _token(IMPORT); }
 "declare"     { return _token(DECLARE); }
+"fn"          { return _token(FN); }
+"import"      { return _token(IMPORT); }
+"trait"       { return _token(TRAIT); }
+"type"        { return _token(TYPE); }
+"unop"        { return _token(UNOP); }
+"val"         { return _token(VAL); }
 
 
 {letter}({digit}|{letter})*   { return _token(IDENTIFIER); }
diff --git a/compiler/parser.yy b/compiler/parser.yy
index 8abd49b..f868a9c 100644
--- a/compiler/parser.yy
+++ b/compiler/parser.yy
@@ -18,7 +18,7 @@
 %define api.location.include {"location.gen.h"}
 
 %code requires {
-#include "AST.h"
+#include "AST/Def.h"
 class ParserDriver;
 }
 
@@ -38,43 +38,57 @@ class ParserDriver;
 
   RARR "->"
   EQUALS "="
+  DOT "."
   COMMA ","
   SEMI ";"
   LPAREN "("
   RPAREN ")"
   LBRACKET "["
   RBRACKET "]"
+  LBRACE "{"
+  RBRACE "}"
 
-  FN "fn"
-  UNOP "unop"
   BINOP "binop"
-  VAL "val"
-  IMPORT "import"
   DECLARE "declare"
+  FN "fn"
+  IMPORT "import"
+  TRAIT "trait"
+  TYPE "type"
+  UNOP "unop"
+  VAL "val"
 ;
 
 %token END 0 "end of file"
 
-%type <std::vector<Stmt *>> stmts;
-%type <Stmt *>
-  stmt
-  decl
+%type <std::vector<ast::Stmt *>>
+  topLevelStmts
+  blockStmts
 ;
 
-%type <FnDecl *> fnDecl;
-%type <ValDecl *> valDecl;
+%type <ast::Stmt *>
+  topLevelStmt
+  blockStmt
+;
 
-%type <Type *>
+%type <ast::FnDecl *> extFnDecl fnDecl;
+%type <ast::ValDecl *> valDecl;
+
+%type <std::vector<ast::Type *>>
+  types
+  tupleTypes
+  fnTypeArgs
+;
+
+%type <ast::Type *>
   type
-  type0
 ;
 
-%type <std::vector<Expr *>>
+%type <std::vector<ast::Expr *>>
   exprs
   args
 ;
 
-%type <Expr *>
+%type <ast::Expr *>
   expr
   expr3
   expr2
@@ -83,8 +97,8 @@ class ParserDriver;
   literal
 ;
 
-%type <FnArg> fnArg;
-%type <std::vector<FnArg>>
+%type <ast::FnArg> fnArg;
+%type <std::vector<ast::FnArg>>
   fnArgs
   fnArgs0
 ;
@@ -95,53 +109,100 @@ class ParserDriver;
 ;
 
 %type <std::string>
+  moduleName
   operator
   identifier
   keyword
 ;
 
+%type <ast::Import *> import;
+%type <std::vector<ast::Import *>>
+  imports0
+  imports
+;
+
 %start module
 
 %%
 
-module: stmts END { driver.module = new Module($1); };
-
-stmts: stmt         { $$ = std::vector<Stmt *>(); $$.push_back($1); }
-     | stmts stmt   { $1.push_back($2); $$ = std::move($1); }
-     ;
-
-stmt: decl;
-
-decl: valDecl { $$ = $1; }
-    | fnDecl  { $$ = $1; }
-    ;
-
-valDecl: VAL identifier "=" expr ";"        { $$ = new ValDecl($2, nullptr, $4); }
-       | VAL identifier type "=" expr ";"   { $$ = new ValDecl($2, $3, $5); }
-       ;
-
-fnDecl: FN identifier "[" fnArgs "]" type "=" expr ";"  { $$ = new FnDecl($2, $4, $6, $8); }
+module: imports topLevelStmts { driver.module = new ast::Module($2); }
       ;
 
-fnArgs: %empty    { $$ = std::vector<FnArg>(); }
+
+imports: %empty     { ; }
+       | imports0   { $$ = std::move($1); }
+       ;
+
+imports0: import            { $$.push_back($1); }
+        | imports0 import   { $1.push_back($2); $$ = std::move($1); }
+        ;
+
+import: IMPORT moduleName ";" { $$ = new ast::Import($2); }
+      ;
+
+moduleName: identifier                  { $$ = $1; }
+          | moduleName "." identifier   { $$ = $1 + $2 + $3; }
+          ;
+
+
+topLevelStmts: topLevelStmt                 { $$.push_back($1); }
+             | topLevelStmts topLevelStmt   { $1.push_back($2); $$ = std::move($1); }
+             ;
+
+topLevelStmt: fnDecl      { $$ = $1; }
+            | extFnDecl   { $$ = $1; }
+            | valDecl     { $$ = $1; }
+            ;
+
+blockStmts: blockStmt              { $$.push_back($1); }
+          | blockStmts blockStmt   { $1.push_back($2); $$ = std::move($1); }
+          ;
+
+blockStmt: valDecl    { $$ = $1; }
+         | fnDecl     { $$ = $1; }
+         | expr ";"   { $$ = new ast::ExprStmt($1); }
+         ;
+
+valDecl: VAL identifier "=" expr ";"        { $$ = new ast::ValDecl($2, nullptr, $4); }
+       | VAL identifier type "=" expr ";"   { $$ = new ast::ValDecl($2, $3, $5); }
+       ;
+
+fnDecl: FN identifier "[" fnArgs "]" type "=" expr ";"  { $$ = new ast::FnDecl($2, $4, $6, $8); }
+      ;
+
+extFnDecl: DECLARE FN identifier "[" fnArgs "]" type ";"  { $$ = new ast::FnDecl($3, $5, $7, nullptr); }
+         ;
+
+fnArgs: %empty    { ; }
       | fnArgs0   { $$ = std::move($1); }
       ;
 
-fnArgs0: fnArg              { $$ = std::vector<FnArg>(); $$.push_back($1); }
+fnArgs0: fnArg              { $$.push_back($1); }
        | fnArgs0 "," fnArg  { $$.push_back($3); $$ = std::move($1); }
        ;
 
-fnArg: identifier type  { $$ = FnArg($1, $2); }
+fnArg: identifier type  { $$ = ast::FnArg($1, $2); }
      ;
 
-type: type0
+types: type             { $$.push_back($1); }
+     | types "," type   { $1.push_back($3); $$ = std::move($1); }
+     ;
+
+type: identifier                     { $$ = new ast::NamedType($1); }
+    | "(" type ")"                   { $$ = $2; }   
+    | "(" tupleTypes ")"             { $$ = new ast::TupleType($2); }
+    | "[" fnTypeArgs "]" "->" type   { $$ = new ast::FunctionType($2, $5); }
     ;
 
-type0: identifier     { $$ = new NamedType($1); }
-     | "(" type ")"   { $$ = $2; }   
-     ;
+tupleTypes: type "," type             { $$.push_back($1); $$.push_back($3); }
+          | tupleTypes "," type       { $1.push_back($3); $$ = std::move($1); }
+          ;
 
-exprs: expr             { $$ = std::vector<Expr *>(); $$.push_back($1); }
+fnTypeArgs: %empty { ; }
+          | types  { $$ = std::move($1); }
+          ;
+
+exprs: expr             { $$.push_back($1); }
      | exprs "," expr   { $1.push_back($3); $$ = std::move($1); }
      ;
 
@@ -150,54 +211,55 @@ expr: expr3 { $$ = $1; }
 
 expr3: expr2                          { $$ = $1; }
      | "[" lambdaArgs "]" "->" expr   { $$ = NULL; }
+     | "{" blockStmts "}"                  { $$ = new ast::BlockExpr($2); }
      ;
 
 expr2: expr1                  { $$ = $1; }
-     | expr2 operator expr1   { $$ = new BinExpr($1, $2, $3); }
+     | expr2 operator expr1   { $$ = new ast::BinExpr($1, $2, $3); }
      ;
 
 expr1: expr0            { $$ = $1; }
-     | operator expr1   { $$ = new UnaryExpr($1, $2); }
+     | operator expr1   { $$ = new ast::UnaryExpr($1, $2); }
      ;
 
 expr0: literal              { $$ = $1; }
-     | identifier           { $$ = new Identifier($1); }
-     | expr0 "[" args "]"   { $$ = new CallExpr($1, $3); }
-     | "(" expr ")"         { $$ = new PrefExpr($2); }
+     | identifier           { $$ = new ast::Identifier($1); }
+     | expr0 "[" args "]"   { $$ = new ast::CallExpr($1, $3); }
+     | "(" expr ")"         { $$ = new ast::PrefExpr($2); }
      ;
 
-lambdaArgs: %empty        { $$ = std::vector<std::string>(); }
+lambdaArgs: %empty        { ; }
           | identifiers   { $$ = std::move($1); }
           ;
 
-args: %empty  { $$ = std::vector<Expr *>(); }
+args: %empty  { ; }
     | exprs   { $$ = std::move($1); }
     ;
 
 
-literal: INT        { $$ = new IntValue($1); }
-       | FLOAT      { $$ = new FloatValue($1); }
+literal: INT        { $$ = new ast::IntValue($1); }
+       | FLOAT      { $$ = new ast::FloatValue($1); }
        ;
 
-operator: "->"      { $$ = $1; }
-        | "="       { $$ = $1; }
-        | OPERATOR  { $$ = $1; }
+operator: "->"
+        | "="
+        | OPERATOR
         ;
 
-identifiers: identifier                   { $$ = std::vector<std::string>(); $$.push_back($1); }
+identifiers: identifier                   { $$.push_back($1); }
            | identifiers "," identifier   { $1.push_back($3); $$ = std::move($1); }
            ;
 
-identifier: keyword     { $$ = $1; }
-          | IDENTIFIER  { $$ = $1; }
+identifier: keyword
+          | IDENTIFIER
           ;
 
-keyword: FN       { $$ = $1; }
-       | VAL      { $$ = $1; }
-       | UNOP     { $$ = $1; }
-       | BINOP    { $$ = $1; }
-       | IMPORT   { $$ = $1; }
-       | DECLARE  { $$ = $1; }
+keyword: FN
+       | VAL
+       | UNOP
+       | BINOP
+       | IMPORT
+       | DECLARE
        ;
 
 %%
diff --git a/compiler/src/main.cpp b/compiler/src/main.cpp
index df22ac9..e2ede87 100644
--- a/compiler/src/main.cpp
+++ b/compiler/src/main.cpp
@@ -25,6 +25,6 @@ int main(int argc, char *argv[])
   auto parser = ParserDriver();
   parser.parse(buf.str());
 
-  auto fn = (FnDecl *)parser.module->stmts.at(0);
+  auto fn = (ast::FnDecl *)parser.module->stmts.at(0);
   std::cout << fn->name << std::endl;
 }
diff --git a/examples/42.plsm b/examples/42.plsm
index 92eb877..1c55ef4 100644
--- a/examples/42.plsm
+++ b/examples/42.plsm
@@ -1 +1,9 @@
+import test.test;
+
 fn main[] Int = 42;
+
+fn test[b Int] Int = {
+  fn helper[] Int = 10;
+  20 * b;
+};
+
diff --git a/examples/stdlib.plsm b/examples/stdlib.plsm
index ac6e258..a6354c0 100644
--- a/examples/stdlib.plsm
+++ b/examples/stdlib.plsm
@@ -1,29 +1,33 @@
-type Bool = class {
+type Bool = {
   declare unop ! Bool;
 
-  declare binop &&(b Bool) Bool;
-  declare binop ||(b Bool) Bool;
+  declare binop &&[b Bool] Bool;
+  declare binop ||[b Bool] Bool;
 };
 
-type Int = class {
+type Int = {
   declare unop + Int;
   declare unop - Int;
 
-  declare binop ==(Int) Bool;
-  declare binop !=(Int) Bool;
-  declare binop >(Int) Bool;
-  declare binop <(Int) Bool;
-  declare binop >=(Int) Bool;
-  declare binop <=(Int) Bool;
+  declare binop ==[Int] Bool;
+  declare binop !=[Int] Bool;
+  declare binop >[Int] Bool;
+  declare binop <[Int] Bool;
+  declare binop >=[Int] Bool;
+  declare binop <=[Int] Bool;
 
-  declare binop +(Int) Int;
-  declare binop -(Int) Int;
-  declare binop *(Int) Int;
-  declare binop /(Int) Int;
-  declare binop %(Int) Int;
+  declare binop +[Int] Int;
+  declare binop -[Int] Int;
+  declare binop *[Int] Int;
+  declare binop /[Int] Int;
+  declare binop %[Int] Int;
 
-  declare factory (f Float);
-  declare factory ();
+  declare factory [f Float];
+  declare factory [];
 
-  declare fn str() String; 
+  declare fn str[] String; 
+};
+
+trait List{T} = {
+  fn
 };