diff options
Diffstat (limited to 'compiler/types/Type.lhs')
| -rw-r--r-- | compiler/types/Type.lhs | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/compiler/types/Type.lhs b/compiler/types/Type.lhs index 579ae754a6..ebf542ab5a 100644 --- a/compiler/types/Type.lhs +++ b/compiler/types/Type.lhs @@ -36,7 +36,7 @@ module Type ( mkTyConApp, mkTyConTy, tyConAppTyCon_maybe, tyConAppArgs_maybe, tyConAppTyCon, tyConAppArgs, - splitTyConApp_maybe, splitTyConApp, + splitTyConApp_maybe, splitTyConApp, tyConAppArgN, mkForAllTy, mkForAllTys, splitForAllTy_maybe, splitForAllTys, mkPiKinds, mkPiType, mkPiTypes, @@ -503,6 +503,13 @@ tyConAppArgs_maybe _ = Nothing tyConAppArgs :: Type -> [Type] tyConAppArgs ty = tyConAppArgs_maybe ty `orElse` pprPanic "tyConAppArgs" (ppr ty) +tyConAppArgN :: Int -> Type -> Type +-- Executing Nth +tyConAppArgN n ty + = case tyConAppArgs_maybe ty of + Just tys -> ASSERT2( n < length tys, ppr n <+> ppr tys ) tys !! n + Nothing -> pprPanic "tyConAppArgN" (ppr n <+> ppr ty) + -- | Attempts to tease a type apart into a type constructor and the application -- of a number of arguments to that constructor. Panics if that is not possible. -- See also 'splitTyConApp_maybe' |