checkTauTvUpdate: take synonym families into account

[ghc-hetmet.git] / compiler / types / FamInstEnv.lhs

diff --git a/compiler/types/FamInstEnv.lhs b/compiler/types/FamInstEnv.lhs
index 9b49f5c..b9276b7 100644 (file)
--- a/compiler/types/FamInstEnv.lhs
+++ b/compiler/types/FamInstEnv.lhs
@@ -6,10 +6,12 @@ FamInstEnv: Type checked family instance declarations
 
 \begin{code}
 module FamInstEnv (
-       FamInst(..), famInstTyCon, pprFamInst, pprFamInstHdr, pprFamInsts, 
+       FamInst(..), famInstTyCon, famInstTyVars, 
+       pprFamInst, pprFamInstHdr, pprFamInsts, 
        famInstHead, mkLocalFamInst, mkImportedFamInst,
 
-       FamInstEnv, emptyFamInstEnv, extendFamInstEnv, extendFamInstEnvList, 
+       FamInstEnvs, FamInstEnv, emptyFamInstEnv, 
+       extendFamInstEnv, extendFamInstEnvList, 
        famInstEnvElts, familyInstances,
 
        lookupFamInstEnv, lookupFamInstEnvUnify
@@ -32,7 +34,6 @@ import UniqFM
 import Outputable
 
 import Maybe
-import Monad
 \end{code}
 
 
@@ -60,6 +61,8 @@ data FamInst
 --
 famInstTyCon :: FamInst -> TyCon
 famInstTyCon = fi_tycon
+
+famInstTyVars = fi_tvs
 \end{code}
 
 \begin{code}
@@ -140,6 +143,9 @@ InstEnv maps a family name to the list of known instances for that family.
 \begin{code}
 type FamInstEnv = UniqFM FamilyInstEnv -- Maps a family to its instances
 
+type FamInstEnvs = (FamInstEnv, FamInstEnv)
+       -- External package inst-env, Home-package inst-env
+
 data FamilyInstEnv
   = FamIE [FamInst]    -- The instances for a particular family, in any order
          Bool          -- True <=> there is an instance of form T a b c
@@ -174,7 +180,7 @@ extendFamInstEnv inst_env ins_item@(FamInst {fi_fam = cls_nm, fi_tcs = mb_tcs})
     add (FamIE items tyvar) _ = FamIE (ins_item:items)
                                      (ins_tyvar || tyvar)
     ins_tyvar = not (any isJust mb_tcs)
-\end{code}                   
+\end{code}
 
 %************************************************************************
 %*                                                                     *
@@ -188,8 +194,7 @@ families), and then, it doesn't matter which match we choose (as the
 instances are guaranteed confluent).
 
 \begin{code}
-lookupFamInstEnv :: (FamInstEnv        -- External package inst-env
-                   ,FamInstEnv)        -- Home-package inst-env
+lookupFamInstEnv :: FamInstEnvs
                 -> TyCon -> [Type]             -- What we are looking for
                 -> [(TvSubst, FamInst)]        -- Successful matches
 lookupFamInstEnv (pkg_ie, home_ie) fam tys