[project @ 2001-10-25 02:13:10 by sof]

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

diff --git a/ghc/compiler/typecheck/TcMType.lhs b/ghc/compiler/typecheck/TcMType.lhs
index d5d394e..9d27e67 100644 (file)
--- a/ghc/compiler/typecheck/TcMType.lhs
+++ b/ghc/compiler/typecheck/TcMType.lhs
@@ -88,7 +88,7 @@ import BasicTypes     ( Boxity, Arity, isBoxed )
 import CmdLineOpts     ( dopt, DynFlag(..) )
 import Unique          ( Uniquable(..) )
 import SrcLoc          ( noSrcLoc )
-import Util            ( nOfThem )
+import Util            ( nOfThem, isSingleton, equalLength )
 import ListSetOps      ( removeDups )
 import Outputable
 \end{code}
@@ -937,11 +937,11 @@ check_inst_head dflags clas tys
   = check_tyvars dflags clas tys
 
        -- WITH HASKELL 1.4, MUST HAVE C (T a b c)
-  | length tys == 1,
+  | isSingleton tys,
     Just (tycon, arg_tys) <- tcSplitTyConApp_maybe first_ty,
     not (isSynTyCon tycon),            -- ...but not a synonym
     all tcIsTyVarTy arg_tys,           -- Applied to type variables
-    length (varSetElems (tyVarsOfTypes arg_tys)) == length arg_tys
+    equalLength (varSetElems (tyVarsOfTypes arg_tys)) arg_tys
           -- This last condition checks that all the type variables are distinct
   = returnTc ()
 
@@ -1114,7 +1114,7 @@ uTys _ (FunTy fun1 arg1) _ (FunTy fun2 arg2)
 
        -- Type constructors must match
 uTys ps_ty1 (TyConApp con1 tys1) ps_ty2 (TyConApp con2 tys2)
-  | con1 == con2 && length tys1 == length tys2
+  | con1 == con2 && equalLength tys1 tys2
   = unifyTauTyLists tys1 tys2
 
   | con1 == openKindCon