shithub: MicroHs

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Slightly better error messages.

--- a/src/MicroHs/TypeCheck.hs

+++ b/src/MicroHs/TypeCheck.hs

@@ -437,18 +437,18 @@

   put (TC mn (n+1) tenv senv venv sub)

   T.return (EUVar n)

-tLookupInst :: Ident -> T (Expr, EType)

-tLookupInst i = T.do

-  (e, s) <- tLookup i

+tLookupInst :: String -> Ident -> T (Expr, EType)

+tLookupInst msg i = T.do

+  (e, s) <- tLookup msg i

 --  traceM ("lookup " ++ show (i, s))

   t <- tInst s

   T.return (e, t)

-tLookup :: Ident -> T (Expr, ETypeScheme)

-tLookup i = T.do

+tLookup :: String -> Ident -> T (Expr, ETypeScheme)

+tLookup msg i = T.do

   env <- gets valueTable

   case M.lookup i env of

-    Nothing -> error $ "undefined variable " ++ i -- ++ "\n" ++ show env ;

+    Nothing -> error $ "undefined, " ++ msg ++ ": " ++ i -- ++ "\n" ++ show env ;

     Just aes ->

       case aes of

         [] -> impossible

@@ -618,7 +618,7 @@

   case adef of

     Fcn i eqns -> T.do

 --      traceM $ "tcDefValue: " ++ showLHS (i, vs) ++ " = " ++ showExpr rhs

-      (_, ETypeScheme tvs tfn) <- tLookup i

+      (_, ETypeScheme tvs tfn) <- tLookup "no type signature" i

       let

         vks = zip tvs (repeat (ETypeScheme [] kType))

       mn <- gets moduleName

@@ -649,7 +649,7 @@

         -- this only happens with patterns translated into expressions

         pair ae <$> newUVar

       else T.do

-        (e, t) <- tLookupInst i

+        (e, t) <- tLookupInst "variable" i

 --        traceM $ "*** " ++ i ++ " :: " ++ showExpr t ++ " = " ++ showMaybe showExpr mt

         munify mt t

         T.return (e, t)

@@ -693,7 +693,7 @@

                 (ea, ta) <- tcExpr mt a

                 let

                   sbind = maybe ">>=" (\ mn -> qual mn ">>=") mmn

-                (EVar qi, _) <- tLookupInst sbind 

+                (EVar qi, _) <- tLookupInst "variable" sbind 

                 let

                   mn = moduleOf qi

                 T.return (EDo (Just mn) [SThen ea], ta)

@@ -760,7 +760,7 @@

       T.return (ECompr ea rss, tr)

     EAt i e -> T.do

       (ee, t) <- tcExpr mt e

-      (_, ti) <- tLookupInst i

+      (_, ti) <- tLookupInst "impossible!" i

       unify t ti

       T.return (EAt i ee, t)

     -----

@@ -863,7 +863,7 @@

 tcBind abind =

   case abind of

     BFcn i eqns -> T.do

-      (_, t) <- tLookupInst i

+      (_, t) <- tLookupInst "impossible!" i

       --(ELam _avs ea, _) <- tcExpr (Just t) $ ELam (map EVar vs) a

       teqns <- tcEqns t eqns

       T.return $ BFcn i teqns

-- 

⑨