[project @ 1996-06-05 06:44:31 by partain]

[ghc-hetmet.git] / ghc / compiler / typecheck / Unify.lhs

diff --git a/ghc/compiler/typecheck/Unify.lhs b/ghc/compiler/typecheck/Unify.lhs
index 39c27f3..77742f4 100644 (file)
--- a/ghc/compiler/typecheck/Unify.lhs
+++ b/ghc/compiler/typecheck/Unify.lhs
@@ -11,7 +11,7 @@ updatable substitution).
 
 module Unify ( unifyTauTy, unifyTauTyList, unifyTauTyLists, unifyFunTy ) where
 
-import Ubiq
+IMP_Ubiq()
 
 -- friends: 
 import TcMonad hiding ( rnMtoTcM )
@@ -229,15 +229,24 @@ uUnboundVar tv1@(TyVar uniq1 kind1 name1 box1)
     case (maybe_ty1, maybe_ty2) of
        (_, BoundTo ty2') -> uUnboundVar tv1 maybe_ty1 ty2' ty2'
 
-       (DontBind,DontBind) 
-                    -> failTc (unifyDontBindErr tv1 ps_ty2)
-
        (UnBound, _) |  kind2 `hasMoreBoxityInfo` kind1
                     -> tcWriteTyVar tv1 ty2            `thenNF_Tc_` returnTc ()
        
        (_, UnBound) |  kind1 `hasMoreBoxityInfo` kind2
                     -> tcWriteTyVar tv2 (TyVarTy tv1)  `thenNF_Tc_` returnTc ()
 
+-- TEMPORARY FIX
+--     (DontBind,DontBind) 
+--                  -> failTc (unifyDontBindErr tv1 ps_ty2)
+
+-- TEMPORARILY allow two type-sig variables to be bound together.
+-- See notes in tcCheckSigVars
+       (DontBind,DontBind) |  kind2 `hasMoreBoxityInfo` kind1
+                           -> tcWriteTyVar tv1 ty2             `thenNF_Tc_` returnTc ()
+       
+                           |  kind1 `hasMoreBoxityInfo` kind2
+                           -> tcWriteTyVar tv2 (TyVarTy tv1)   `thenNF_Tc_` returnTc ()
+
        other        -> failTc (unifyKindErr tv1 ps_ty2)
 
        -- Second one isn't a type variable