diff --git a/CMakeLists.txt b/CMakeLists.txt
index ee5a34a..d5de47b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -44,6 +44,8 @@ set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 set(LEX_SOURCE_FILE ${PROJECT_SOURCE_DIR}/src/lex/lexer.l)
 set(LEX_GENERATED_SOURCE_FILE ${PROJECT_SOURCE_DIR}/src/lex/lexer.ll.c)
 
+file(REMOVE ${LEX_GENERATED_SOURCE_FILE})
+
 add_custom_command(OUTPUT ${LEX_GENERATED_SOURCE_FILE}
         COMMAND lex
         ARGS -o  ${LEX_GENERATED_SOURCE_FILE} ${LEX_SOURCE_FILE}
@@ -62,6 +64,8 @@ endif()
 set(YACC_SOURCE_FILE ${PROJECT_SOURCE_DIR}/src/yacc/parser.y)
 set(YACC_GENERATED_SOURCE_FILE ${PROJECT_SOURCE_DIR}/src/yacc/parser.tab.c)
 
+file(REMOVE ${YACC_GENERATED_SOURCE_FILE})
+
 add_custom_command(OUTPUT ${YACC_GENERATED_SOURCE_FILE}
         COMMAND bison
         ARGS -Wno-yacc -Wcounterexamples -d -o ${YACC_GENERATED_SOURCE_FILE} ${YACC_SOURCE_FILE}
diff --git a/src/ast/ast.c b/src/ast/ast.c
index a0321bb..582c3d4 100644
--- a/src/ast/ast.c
+++ b/src/ast/ast.c
@@ -86,6 +86,7 @@ void AST_init() {
     lookup_table[AST_AddressOf] = "address of";
     lookup_table[AST_Dereference] = "deref";
     lookup_table[AST_Reference] = "ref";
+    lookup_table[AST_Reference] = "ret";
 }
 
 const char* AST_node_to_string(const struct AST_Node_t* node) {
diff --git a/src/ast/ast.h b/src/ast/ast.h
index ea2b332..4ead853 100644
--- a/src/ast/ast.h
+++ b/src/ast/ast.h
@@ -81,6 +81,7 @@ enum AST_SyntaxElement_t {
     AST_Reference,
     AST_Include,
     AST_Char,
+    AST_Return,
     AST_ELEMENT_COUNT
 };
 
diff --git a/src/lex/lexer.l b/src/lex/lexer.l
index d98c1da..9902ea4 100644
--- a/src/lex/lexer.l
+++ b/src/lex/lexer.l
@@ -90,6 +90,7 @@
 "funname" {DEBUG("\"%s\" tokenized with \'FunFunname\'", yytext); return(FunFunname);};
 "lineno" {DEBUG("\"%s\" tokenized with \'FunLineno\'", yytext); return(FunLineno);};
 "extsupport" {DEBUG("\"%s\" tokenized with \'FunExtsupport\'", yytext); return(FunExtsupport);};
+"ret" {DEBUG("\"%s\" tokenized with \'Return\'", yytext); return(KeyReturn);};
 
 [0-9]+    {DEBUG("\"%s\" tokenized with \'ValInt\'", yytext); yylval.string = mem_strdup(MemoryNamespaceLex, yytext); return(ValInt); };
 [0-9]*\.[0-9]+ {DEBUG("\"%s\" tokenized with \'ValFloat\'", yytext); yylval.string = mem_strdup(MemoryNamespaceLex, yytext); return(ValFloat);};
diff --git a/src/yacc/parser.y b/src/yacc/parser.y
index 3408b94..d1468fd 100644
--- a/src/yacc/parser.y
+++ b/src/yacc/parser.y
@@ -72,6 +72,7 @@
 %type <node_ptr> reinterpretcast
 %type <node_ptr> program
 %type <node_ptr> storage_expr
+%type <node_ptr> return
 
 
 %token KeyInt
@@ -122,6 +123,7 @@
 %token FunLineno
 %token FunExtsupport
 %token Invalid
+%token KeyReturn
 
 /* Operator associativity */
 /* Operators at lower line number have lower precedence */
@@ -192,11 +194,20 @@ argumentlist: argumentlist '(' exprlist ')' {AST_push_node($1, $3);
               $$ = list;};
 
 
+// TODO: add ast node for definition and declaration
 fundef: KeyFun Ident paramlist '{' statementlist'}' {AST_NODE_PTR fun = AST_new_node(new_loc(), AST_Fun, NULL);
                                                      AST_NODE_PTR ident = AST_new_node(new_loc(), AST_Ident, $2);
                                                      AST_push_node(fun, ident);
                                                      AST_push_node(fun, $3);
                                                      AST_push_node(fun, $5);
+                                                     $$ = fun;
+                                                            DEBUG("Function");}
+        | KeyFun Ident paramlist ':' type '{' statementlist'}' {AST_NODE_PTR fun = AST_new_node(new_loc(), AST_Fun, NULL);
+                                                     AST_NODE_PTR ident = AST_new_node(new_loc(), AST_Ident, $2);
+                                                     AST_push_node(fun, ident);
+                                                     AST_push_node(fun, $3);
+                                                     AST_push_node(fun, $5);
+                                                     AST_push_node(fun, $7);
                                                      $$ = fun;
                                                             DEBUG("Function");};
 
@@ -205,7 +216,13 @@ fundecl: KeyFun Ident paramlist {AST_NODE_PTR fun = AST_new_node(new_loc(), AST_
                                  AST_push_node(fun, ident);
                                  AST_push_node(fun, $3);
                                  $$ = fun;
-                                        DEBUG("Function");};
+                                        DEBUG("Function");}
+        | KeyFun Ident paramlist ':' type {AST_NODE_PTR fun = AST_new_node(new_loc(), AST_Fun, NULL);
+                                           AST_NODE_PTR ident = AST_new_node(new_loc(), AST_Ident, $2);
+                                           AST_push_node(fun, ident);
+                                           AST_push_node(fun, $3);
+                                           $$ = fun;
+                                                  DEBUG("Function");};
 
 paramlist: paramlist '(' params ')' {AST_push_node($1, $3);
                                      $$ = $1;}
@@ -348,9 +365,13 @@ statement: assign {$$ = $1;}
         | definition {$$ = $1;}
         | while {$$ = $1;}
         | branchfull {$$ = $1;}
+        | return {$$ = $1;}
         | funcall {$$ = $1;}
         | boxcall{$$ = $1;};
 
+return: KeyReturn expr { AST_NODE_PTR return_stmt = AST_new_node(new_loc(), AST_Return, NULL);
+                         AST_push_node(return_stmt, $2); };
+
 branchif: KeyIf expr '{' statementlist '}' { AST_NODE_PTR branch = AST_new_node(new_loc(), AST_If, NULL);
                                             AST_push_node(branch, $2);
                                             AST_push_node(branch, $4);
diff --git a/tests/stdlib/src/matrix.gsc b/tests/stdlib/src/matrix.gsc
index e14b1a3..234629f 100644
--- a/tests/stdlib/src/matrix.gsc
+++ b/tests/stdlib/src/matrix.gsc
@@ -92,7 +92,10 @@ fun test_matrix()
     heapFree(matrix as ref u8)
 }
 
-fun main()
+fun main(): u32
 {
     test_matrix()
+    exit_code = 0
+
+    ret 0
 }