Commit 1fce2c3a authored by Simon Peyton Jones's avatar Simon Peyton Jones

Avoid quadratic complexity in typeKind

I took 10 minute to fix this potential performance hole
(Trac #14263)

There are no actual bug reports against it, so no regression
test.
parent f13a0fc0
......@@ -2296,7 +2296,7 @@ nonDetCmpTc tc1 tc2
typeKind :: HasDebugCallStack => Type -> Kind
typeKind (TyConApp tc tys) = piResultTys (tyConKind tc) tys
typeKind (AppTy fun arg) = piResultTy (typeKind fun) arg
typeKind (AppTy fun arg) = typeKind_apps fun [arg]
typeKind (LitTy l) = typeLiteralKind l
typeKind (FunTy {}) = liftedTypeKind
typeKind (ForAllTy _ ty) = typeKind ty
......@@ -2304,6 +2304,15 @@ typeKind (TyVarTy tyvar) = tyVarKind tyvar
typeKind (CastTy _ty co) = pSnd $ coercionKind co
typeKind (CoercionTy co) = coercionType co
typeKind_apps :: HasDebugCallStack => Type -> [Type] -> Kind
-- The sole purpose of the function is to accumulate
-- the type arugments, so we can call piResultTys, rather than
-- a succession of calls to piResultTy (which is asymptotically
-- less efficient as the number of arguments increases)
typeKind_apps (AppTy fun arg) args = typeKind_apps fun (arg:args)
typeKind_apps fun args = piResultTys (typeKind fun) args
--------------------------
typeLiteralKind :: TyLit -> Kind
typeLiteralKind l =
case l of
......
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