Add a type synonym for FamInstEnvs

diff --git a/compiler/types/FamInstEnv.lhs b/compiler/types/FamInstEnv.lhs
index eb31751..b851ec1 100644 (file)
--- a/compiler/types/FamInstEnv.lhs
+++ b/compiler/types/FamInstEnv.lhs
@@ -10,7 +10,8 @@ module FamInstEnv (
        pprFamInst, pprFamInstHdr, pprFamInsts, 
        famInstHead, mkLocalFamInst, mkImportedFamInst,
 
-       FamInstEnv, emptyFamInstEnv, extendFamInstEnv, extendFamInstEnvList, 
+       FamInstEnvs, FamInstEnv, emptyFamInstEnv, 
+       extendFamInstEnv, extendFamInstEnvList, 
        famInstEnvElts, familyInstances,
 
        lookupFamInstEnv, lookupFamInstEnvUnify
@@ -142,6 +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
@@ -236,8 +240,7 @@ 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