Fix #15236 by removing parentheses from funTyConName

Currently, `funTyConName` is defined as:

```lang=haskell
funTyConName = mkPrimTyConName (fsLit "(->)") funTyConKey funTyCon
```

What's strange about this definition is that there are extraneous
parentheses around `->`, which is quite unlike every other infix
`Name`. As a result, the `:info (->)` output is totally garbled (see
Trac #15236).

It's quite straightforward to fix that particular bug by removing the
extraneous parentheses. However, it turns out that this makes some
test output involving `Show` instances for `TypeRep` look less
appealing, since `->` is no longer surrounded with parentheses when
applied prefix. But neither were any /other/ infix type constructors!
The right fix there was to change `showTypeable` to put parentheses
around prefix applications of infix tycons.

Test Plan: ./validate

Reviewers: bgamari, hvr

Reviewed By: bgamari

Subscribers: rwbarton, thomie, carter

GHC Trac Issues: #15236

Differential Revision: https://phabricator.haskell.org/D4799

1 files changed, 1 insertions, 1 deletions

diff --git a/compiler/prelude/TysPrim.hs b/compiler/prelude/TysPrim.hs
index ff61878964..754bb8fb09 100644
--- a/compiler/prelude/TysPrim.hs
+++ b/compiler/prelude/TysPrim.hs
@@ -340,7 +340,7 @@ openBetaTy  = mkTyVarTy openBetaTyVar
 -}
 
 funTyConName :: Name
-funTyConName = mkPrimTyConName (fsLit "(->)") funTyConKey funTyCon
+funTyConName = mkPrimTyConName (fsLit "->") funTyConKey funTyCon
 
 -- | The @(->)@ type constructor.
 --