diff --git a/bsc/astgen/AST.py b/bsc/astgen/AST.py
index d3b7ef6..0ee0221 100644
--- a/bsc/astgen/AST.py
+++ b/bsc/astgen/AST.py
@@ -622,6 +622,22 @@ def __eq__(self, other):
             return str(self.expr) == str(other.expr)
         return False
 
+class ResultType:
+    def __init__(self, type, pos):
+        self.type = type
+        self.pos = pos
+
+    def __str__(self):
+        return f"!{self.type}"
+
+    def __repr__(self):
+        return str(self)
+
+    def __eq__(self, other):
+        if isinstance(other, ResultType):
+            return self.type == other.type
+        return False
+
 class OptionType:
     def __init__(self, type, pos):
         self.type = type
@@ -657,7 +673,7 @@ def __eq__(self, other):
             return str(self.size) == str(other.size) and self.type == other.type
         return False
 
-class MapType:
+class TableType:
     def __init__(self, k_type, v_type, pos):
         self.k_type = k_type
         self.v_type = v_type
@@ -670,7 +686,7 @@ def __repr__(self):
         return str(self)
 
     def __eq__(self, other):
-        if isinstance(other, MapType):
+        if isinstance(other, TableType):
             return self.k_type == other.k_type and self.v_type == other.v_type
         return False
 
diff --git a/bsc/astgen/__init__.py b/bsc/astgen/__init__.py
index d4623f7..62dec3a 100644
--- a/bsc/astgen/__init__.py
+++ b/bsc/astgen/__init__.py
@@ -130,9 +130,15 @@ def fn_decl(self, *nodes):
         else:
             args = []
         ret_type = nodes[6]
-        if isinstance(ret_type, BlockExpr
-                      ) or isinstance(ret_type, Token) or not ret_type:
+        is_result = isinstance(ret_type, Token) and str(ret_type) == "!"
+        if is_result:
+            ret_type = nodes[7]
+        if isinstance(ret_type,
+                      BlockExpr) or isinstance(ret_type,
+                                               Token) or (not ret_type):
             ret_type = self.ctx.void_type
+        if is_result:
+            ret_type = ResultType(ret_type, self.mkpos(nodes[6]))
         stmts = []
         if len(nodes) == 8:
             stmts = nodes[-1]
@@ -533,7 +539,7 @@ def access_modifier(self, *nodes):
         return AccessModifier.private
 
     # Types
-    def user_type(self, *names):
+    def user_type_decl(self, *names):
         left = names[0]
         if isinstance(left, Ident):
             match left.name:
@@ -555,20 +561,20 @@ def user_type(self, *names):
                     return BasicType(left, left.pos)
         return BasicType(left, left.pos)
 
-    def option_type(self, *nodes):
+    def option_type_decl(self, *nodes):
         return OptionType(nodes[1], self.mkpos(nodes[0]))
 
-    def array_type(self, *nodes):
+    def array_type_decl(self, *nodes):
         has_size = not isinstance(nodes[1], Token)
         size = nodes[1] if has_size else None
         return ArrayType(
             size, nodes[3 if has_size else 2], self.mkpos(nodes[0])
         )
 
-    def map_type(self, *nodes):
-        return MapType(nodes[1], nodes[3], self.mkpos(nodes[0]))
+    def table_type_decl(self, *nodes):
+        return TableType(nodes[1], nodes[3], self.mkpos(nodes[0]))
 
-    def sum_type(self, *nodes):
+    def sum_type_decl(self, *nodes):
         types = list(filter(lambda node: not isinstance(node, Token), nodes))
         return SumType(types, nodes[0].pos)
 
diff --git a/bsc/astgen/grammar.lark b/bsc/astgen/grammar.lark
index 5fcc5ca..1c5c3b6 100644
--- a/bsc/astgen/grammar.lark
+++ b/bsc/astgen/grammar.lark
@@ -34,30 +34,30 @@ use_tree: path_expr DOUBLE_COLON MUL
 
 mod_decl: [access_modifier] KW_MOD NAME (LBRACE decl* RBRACE | SEMICOLON)
 
-const_decl: [access_modifier] KW_CONST NAME [COLON type] OP_ASSIGN expr SEMICOLON
+const_decl: [access_modifier] KW_CONST NAME [COLON type_decl] OP_ASSIGN expr SEMICOLON
 
 var_decl: [access_modifier] KW_VAR var_ident (COMMA var_ident)* OP_ASSIGN expr SEMICOLON
-var_ident: NAME [COLON type]
+var_ident: NAME [COLON type_decl]
 
 enum_decl: [access_modifier] KW_ENUM NAME LBRACE enum_fields decl* RBRACE
 enum_fields: enum_field (COMMA enum_field)*
 enum_field: NAME [OP_ASSIGN expr]
 
 class_decl: [access_modifier] KW_CLASS NAME LBRACE (class_field | decl)* RBRACE
-class_field: [access_modifier] NAME COLON type [OP_ASSIGN expr] SEMICOLON
+class_field: [access_modifier] NAME COLON type_decl [OP_ASSIGN expr] SEMICOLON
 
-fn_decl: [access_modifier] KW_FN NAME LPAREN [fn_args] RPAREN [BANG | type] (SEMICOLON | block)
+fn_decl: [access_modifier] KW_FN NAME LPAREN [fn_args] RPAREN [BANG? type_decl] (SEMICOLON | block)
 fn_args: (KW_SELF | fn_arg) (COMMA fn_arg)*
-fn_arg: NAME COLON type [OP_ASSIGN expr]
+fn_arg: NAME COLON type_decl [OP_ASSIGN expr]
 
 access_modifier: KW_PUB [LPAREN KW_PKG RPAREN] | KW_PROT
 
-?type: path_expr -> user_type
-       | QUESTION type -> option_type
-       | LBRACKET expr? RBRACKET type -> array_type
-       | LBRACE type COLON type RBRACE -> map_type
-       | type PIPE type (PIPE type)* -> sum_type
-       | LPAREN type COMMA type (COMMA type)* RPAREN -> tuple_type
+?type_decl: path_expr -> user_type_decl
+       | QUESTION type_decl -> option_type_decl
+       | LBRACKET expr? RBRACKET type_decl -> array_type_decl
+       | LBRACE type_decl COLON type_decl RBRACE -> table_type_decl
+       | type_decl PIPE type_decl (PIPE type_decl)* -> sum_type_decl
+       | LPAREN type_decl COMMA type_decl (COMMA type_decl)* RPAREN -> tuple_type_decl
 
 // Statements
 
@@ -97,7 +97,7 @@ unary_expr: unary_op primary_expr | primary_expr
        | block_expr
        | expr LPAREN [expr (COMMA expr)*] RPAREN -> call_expr
        | LPAREN expr (COMMA expr)* RPAREN -> tuple_literal
-       | LBRACE expr COLON expr (COMMA expr COLON expr)* RBRACE -> map_literal
+       | LBRACE expr COLON expr (COMMA expr COLON expr)* RBRACE -> table_literal
        | [HASH] LBRACKET [expr (COMMA expr)*] RBRACKET -> array_literal
        | DOT NAME -> enum_literal
        | path_expr
diff --git a/bsc/sym.py b/bsc/sym.py
index fcc8974..dd811fc 100644
--- a/bsc/sym.py
+++ b/bsc/sym.py
@@ -115,7 +115,7 @@ class TypeKind(IntEnum):
     float = auto()
     string = auto()
     array = auto()
-    map = auto()
+    table = auto()
     tuple = auto()
     sumtype = auto()
     enum = auto()
@@ -141,8 +141,8 @@ def __str__(self):
                 return "string"
             case TypeKind.array:
                 return "array"
-            case TypeKind.map:
-                return "map"
+            case TypeKind.table:
+                return "table"
             case TypeKind.tuple:
                 return "tuple"
             case TypeKind.sumtype:
diff --git a/tests/main.bs b/tests/main.bs
index 7a47c6c..5c14f96 100644
--- a/tests/main.bs
+++ b/tests/main.bs
@@ -9,7 +9,7 @@ const float_num = 0.5e4;
 const f = 1.0 / 2.0;
 const i = 1 / 2;
 
-fn main() void {
+fn main() !void {
     print("hello");
     const XXX = dec_num;
 }