Merge pull request #77 from Hoxmot/feature/15-static-typing

[#62] Static typing: Lambdas

src/Interpreter.hs

@@ -108,7 +108,8 @@ createFuncEnv env ((Arg t v):als) (a:as) = do
     arg <- interpretExp a
     if typeEq t arg
         then createFuncEnv (M.insert v (Var arg) env) als as
-        else throwError "Types don't match!"
+        else throwError $ "Types don't match! Expected '" ++ pprintType t
+            ++ "', but got '" ++ pprintResult arg ++ "'!"
 createFuncEnv env [] [] = return env
 createFuncEnv _ [] _ = throwError "Too many arguments!"
 createFuncEnv _ _ _ = throwError "Partial function application is not supported yet!"
@@ -119,7 +120,8 @@ interpretFuncBody t exps = do
     res <- interpretExps exps
     if typeEq t res
         then return res
-        else throwError "Types don't match!"
+        else throwError $ "Types don't match! Expected '" ++ pprintType t
+            ++ "', but got '" ++ pprintResult res ++ "'!"
 
 
 {- | Interprets an internal function usage in Baalbolge.

src/TypeChecker.hs

@@ -199,6 +199,25 @@ checkTypesIFunc iFunc@(BG.IFuncDecl pos t (BG.Var v) (BG.AList _ argsList) exps)
   where
     argToType (BG.AArg _ at _) = checkTypesType at
 
+{- | For the lambda declaration, we have to make sure that the type returned by the
+function body is the same as the declared return type. However, first, we have to make
+sure that all the expressions inside the body of the function have the correct type.
+
+The type of the function declaration is the function itself.
+-}
+checkTypesIFunc iFunc@(BG.ILambda pos t (BG.AList _ argsList) exps) = do
+    tt <- checkTypesType t
+    args <- mapM argToType argsList
+    mem <- get
+    funcMem <- foldM createFuncMem mem argsList
+    case runReader (runExceptT $ checkTypesExps exps) funcMem of
+        Left l  -> throwError l
+        Right ft -> if tt == ft
+            then return $ TFunc tt args
+            else throwError $ typesError iFunc "lambda declaration" pos tt ft
+  where
+    argToType (BG.AArg _ at _) = checkTypesType at
+
 checkTypesIFunc e = throwError $ "Checking types for internal function: " ++ show e
     ++ " is not yet implemented"