Comments, plus type sigs

compiler/hsSyn/HsPat.lhs

@@ -131,7 +131,7 @@ data Pat id
   | CoPat 	HsWrapper		-- If co::t1 -> t2, p::t2, 
 					-- then (CoPat co p) :: t1
 		(Pat id)		-- Why not LPat?  Ans: existing locn will do
-	    	Type
+	    	Type			-- Type of whole pattern, t1
 	-- During desugaring a (CoPat co pat) turns into a cast with 'co' on 
 	-- the scrutinee, followed by a match on 'pat'
 \end{code}

compiler/typecheck/FamInst.lhs

@@ -65,6 +65,7 @@ instance Ord ModulePair where
 --
 type ModulePairSet = FiniteMap ModulePair ()
 
+listToSet :: [ModulePair] -> ModulePairSet
 listToSet l = listToFM (zip l (repeat ()))
 
 checkFamInstConsistency :: [Module] -> [Module] -> TcM ()

compiler/typecheck/TcPat.lhs

@@ -584,8 +584,7 @@ tcConPat pstate con_span data_con tycon pat_ty arg_pats thing_inside
 	}
   where
     -- Split against the family tycon if the pattern constructor 
-    -- belongs to a representation tycon.
-    --
+    -- belongs to a family instance tycon.
     boxySplitTyConAppWithFamily tycon pat_ty =
       traceTc traceMsg >>
       case tyConFamInst_maybe tycon of