Commit 5bcf8606 authored by Ryan Scott's avatar Ryan Scott

Remove duplicate Note [When to print foralls] in GHC.Core.TyCo.Ppr

There are two different Notes named `[When to print foralls]`. The
most up-to-date one is in `GHC.Iface.Type`, but there is a second
one in `GHC.Core.TyCo.Ppr`. The latter is less up-to-date, as it was
written before GHC switched over to using ifaces to pretty-print
types. I decided to just remove the latter and replace it with a
reference to the former.

[ci skip]
parent 568d7279
Pipeline #19593 skipped
......@@ -171,7 +171,8 @@ pprSigmaType = pprIfaceSigmaType ShowForAllWhen . tidyToIfaceType
pprForAll :: [TyCoVarBinder] -> SDoc
pprForAll tvs = pprIfaceForAll (map toIfaceForAllBndr tvs)
-- | Print a user-level forall; see Note [When to print foralls] in this module.
-- | Print a user-level forall; see @Note [When to print foralls]@ in
-- "GHC.Iface.Type".
pprUserForAll :: [TyCoVarBinder] -> SDoc
pprUserForAll = pprUserIfaceForAll . map toIfaceForAllBndr
......@@ -253,24 +254,6 @@ debug_ppr_ty prec ty@(ForAllTy {})
= ([], ty)
{-
Note [When to print foralls]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Mostly we want to print top-level foralls when (and only when) the user specifies
-fprint-explicit-foralls. But when kind polymorphism is at work, that suppresses
too much information; see #9018.
So I'm trying out this rule: print explicit foralls if
a) User specifies -fprint-explicit-foralls, or
b) Any of the quantified type variables has a kind
that mentions a kind variable
This catches common situations, such as a type siguature
f :: m a
which means
f :: forall k. forall (m :: k->*) (a :: k). m a
We really want to see both the "forall k" and the kind signatures
on m and a. The latter comes from pprTCvBndr.
Note [Infix type variables]
~~~~~~~~~~~~~~~~~~~~~~~~~~~
With TypeOperators you can say
......
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