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| author | Simon Peyton Jones <simonpj@microsoft.com> | 2018-11-05 13:48:27 +0000 |
|---|---|---|
| committer | Simon Peyton Jones <simonpj@microsoft.com> | 2018-11-15 09:05:23 +0000 |
| commit | fe0576426d3ef07d7743c65e34c8b04ce0616426 (patch) | |
| tree | 24a024f6e60bd8afd58d99ed2721bec736ab16aa | |
| parent | eb46345d37ee61575e6fed04da718c1b7ee0bb99 (diff) | |
| download | haskell-fe0576426d3ef07d7743c65e34c8b04ce0616426.tar.gz | |
Comments only, about polykinded TyConApps
See Trac #15704 comment:8ff
| -rw-r--r-- | compiler/types/Unify.hs | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/compiler/types/Unify.hs b/compiler/types/Unify.hs index 951a3f9f93..62d53dc60a 100644 --- a/compiler/types/Unify.hs +++ b/compiler/types/Unify.hs @@ -888,6 +888,17 @@ Note that * One better way is to ensure that type patterns (the template in the matching process) have no casts. See Trac #14119. +Note [Polykinded tycon applications] +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Suppose T :: forall k. Type -> K +and we are unifying + ty1: T @Type Int :: Type + ty2: T @(Type->Type) Int Int :: Type + +These two TyConApps have the same TyCon at the front but they +(legitimately) have different numbers of arguments. They +are surelyApart, so we can report that without looking any +further (see Trac #15704). -} -------------- unify_ty: the main workhorse ----------- @@ -1025,7 +1036,8 @@ unify_tys env orig_xs orig_ys = do { unify_ty env x y (mkNomReflCo $ typeKind x) ; go xs ys } go _ _ = surelyApart - -- Possibly different saturations of a polykinded tycon (See Trac #15704) + -- Possibly different saturations of a polykinded tycon + -- See Note [Polykinded tycon applications] --------------------------------- uVar :: UMEnv |