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

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

diff --git a/ghc/compiler/typecheck/TcGenDeriv.lhs b/ghc/compiler/typecheck/TcGenDeriv.lhs
index 273572b..eafae42 100644 (file)
--- a/ghc/compiler/typecheck/TcGenDeriv.lhs
+++ b/ghc/compiler/typecheck/TcGenDeriv.lhs
@@ -57,7 +57,7 @@ import TcType         ( isUnLiftedType, tcEqType, Type )
 import TysPrim         ( charPrimTy, intPrimTy, wordPrimTy, addrPrimTy,
                          floatPrimTy, doublePrimTy
                        )
-import Util            ( mapAccumL, zipEqual, zipWithEqual,
+import Util            ( mapAccumL, zipEqual, zipWithEqual, isSingleton,
                          zipWith3Equal, nOfThem )
 import Panic           ( panic, assertPanic )
 import Maybes          ( maybeToBool, orElse )
@@ -351,7 +351,7 @@ gen_Ord_binds tycon
     cmp_eq =
        mk_FunMonoBind tycon_loc 
                       cmp_eq_RDR 
-                      (if null nonnullary_cons && (length nullary_cons == 1) then
+                      (if null nonnullary_cons && isSingleton nullary_cons then
                           -- catch this specially to avoid warnings
                           -- about overlapping patterns from the desugarer.
                          let 
@@ -363,7 +363,7 @@ gen_Ord_binds tycon
                       else
                          map pats_etc nonnullary_cons ++
                          -- leave out wildcards to silence desugarer.
-                         (if length tycon_data_cons == 1 then
+                         (if isSingleton tycon_data_cons then
                              []
                           else
                               [([WildPatIn, WildPatIn], default_rhs)]))
@@ -527,7 +527,7 @@ gen_Bounded_binds tycon
   = if isEnumerationTyCon tycon then
        min_bound_enum `AndMonoBinds` max_bound_enum
     else
-       ASSERT(length data_cons == 1)
+       ASSERT(isSingleton data_cons)
        min_bound_1con `AndMonoBinds` max_bound_1con
   where
     data_cons = tyConDataCons tycon