From a33620210a161a20b60a138a0b984a5336a45f2d Mon Sep 17 00:00:00 2001
From: "Juan J. Martinez" <jjm@usebox.net>
Date: Sun, 4 Sep 2022 08:21:31 +0100
Subject: Type-checking variable declaration

---
 src/Compiler.hs  | 11 ++++++++++-
 test/Language.hs | 20 +++++++++++++++++++-
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/Compiler.hs b/src/Compiler.hs
index f36083c..40e5f73 100644
--- a/src/Compiler.hs
+++ b/src/Compiler.hs
@@ -153,7 +153,16 @@ compile x = do
           if not (definedType typ)
             then Error UndefinedType ("undefined type in variable declaration \"" ++ ident ++ "\"") pos : errs
             else errs
-      -- TODO: typecheck value
+      -- type-check value
+      vt <- compile val
+      errs <- case vt of
+        Right (Just t) ->
+          if t == typ
+            then return $ errs
+            else return $ (Error TypeError ("value type mismatch\n     found: " ++ show t ++ "\n  expected: " ++ show typ) pos) : errs
+        _ -> do
+          (_, errs) <- get -- error resolving value
+          return $ errs
       put (ev, errs)
       return $ Right $ Just typ
     (A.Return value pos) -> do
diff --git a/test/Language.hs b/test/Language.hs
index 19ec5bf..84c72ae 100644
--- a/test/Language.hs
+++ b/test/Language.hs
@@ -309,6 +309,22 @@ testCaseE12 =
         \var a: undef = 1;\n"
         E.UndefinedType
 
+testCaseE13 =
+  TestLabel "type mismatch in variable declaration" $
+    TestCase $
+      expectError
+        "module main\n\
+        \var a: bool = 0;\n"
+        E.TypeError
+
+testCaseE14 =
+  TestLabel "type mismatch in variable declaration (lambda)" $
+    TestCase $
+      expectError
+        "module main\n\
+        \var a: bool = (a:u8): u8 { return a; };\n"
+        E.TypeError
+
 language =
   [ testCase2,
     testCase3,
@@ -334,5 +350,7 @@ language =
     testCaseE9,
     testCaseE10,
     testCaseE11,
-    testCaseE12
+    testCaseE12,
+    testCaseE13,
+    testCaseE14
   ]
-- 
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