diff options
Diffstat (limited to 'compiler/types/Type.lhs')
| -rw-r--r-- | compiler/types/Type.lhs | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/compiler/types/Type.lhs b/compiler/types/Type.lhs index 8a9cf0eac6..8177e5ac9d 100644 --- a/compiler/types/Type.lhs +++ b/compiler/types/Type.lhs @@ -30,7 +30,7 @@ module Type ( mkFunTy, mkFunTys, splitFunTy, splitFunTy_maybe, splitFunTys, splitFunTysN, - funResultTy, funArgTy, zipFunTys, + funResultTy, funArgTy, zipFunTys, typeArity, mkTyConApp, mkTyConTy, tyConAppTyCon, tyConAppArgs, @@ -141,6 +141,7 @@ import VarSet import Name import Class import TyCon +import BasicTypes ( Arity ) -- others import StaticFlags @@ -495,6 +496,14 @@ funArgTy :: Type -> Type funArgTy ty | Just ty' <- coreView ty = funArgTy ty' funArgTy (FunTy arg _res) = arg funArgTy ty = pprPanic "funArgTy" (ppr ty) + +typeArity :: Type -> Arity +-- How many value arrows are visible in the type? +-- We look through foralls, but not through newtypes, dictionaries etc +typeArity ty | Just ty' <- coreView ty = typeArity ty' +typeArity (FunTy _ ty) = 1 + typeArity ty +typeArity (ForAllTy _ ty) = typeArity ty +typeArity _ = 0 \end{code} --------------------------------------------------------------------- @@ -1334,7 +1343,7 @@ then (substTy subst ty) does nothing. For example, consider: (/\a. /\b:(a~Int). ...b..) Int We substitute Int for 'a'. The Unique of 'b' does not change, but -nevertheless we add 'b' to the TvSubstEnv, because b's type does change +nevertheless we add 'b' to the TvSubstEnv, because b's kind does change This invariant has several crucial consequences: |