[commit: ghc] master: base: Fix a few TODOs in Typeable.Internal (6166b59)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : master
Link       : http://ghc.haskell.org/trac/ghc/changeset/6166b59fadb8714cd497902c8469fd2b3b6caf46/ghc

>---------------------------------------------------------------

commit 6166b59fadb8714cd497902c8469fd2b3b6caf46
Author: Ben Gamari <bgamari.foss at gmail.com>
Date:   Tue May 23 09:42:12 2017 -0400

    base: Fix a few TODOs in Typeable.Internal
    
    Test Plan: Validate
    
    Reviewers: austin, hvr, dfeuer
    
    Reviewed By: dfeuer
    
    Subscribers: rwbarton, thomie
    
    GHC Trac Issues: #13746
    
    Differential Revision: https://phabricator.haskell.org/D3605


>---------------------------------------------------------------

6166b59fadb8714cd497902c8469fd2b3b6caf46
 libraries/base/Data/Typeable/Internal.hs | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/libraries/base/Data/Typeable/Internal.hs b/libraries/base/Data/Typeable/Internal.hs
index 48da8dd..cf645ad 100644
--- a/libraries/base/Data/Typeable/Internal.hs
+++ b/libraries/base/Data/Typeable/Internal.hs
@@ -187,9 +187,6 @@ data TypeRep (a :: k) where
             -> TypeRep b
             -> TypeRep (a -> b)
 
-on :: (a -> a -> r) -> (b -> a) -> (b -> b -> r)
-on f g = \ x y -> g x `f` g y
-
 -- Compare keys for equality
 
 -- | @since 2.01
@@ -207,7 +204,8 @@ instance TestEquality TypeRep where
 
 -- | @since 4.4.0.0
 instance Ord (TypeRep a) where
-  compare = compare `on` typeRepFingerprint
+  compare _ _ = EQ
+  {-# INLINABLE compare #-}
 
 -- | A non-indexed type representation.
 data SomeTypeRep where
@@ -305,11 +303,11 @@ someTypeRepTyCon (SomeTypeRep t) = typeRepTyCon t
 typeRepTyCon :: TypeRep a -> TyCon
 typeRepTyCon (TrTyCon _ tc _) = tc
 typeRepTyCon (TrApp _ a _)    = typeRepTyCon a
-typeRepTyCon (TrFun _ _ _)    = error "typeRepTyCon: FunTy" -- TODO
+typeRepTyCon (TrFun _ _ _)    = typeRepTyCon $ typeRep @(->)
 
 -- | Type equality
 --
--- @since TODO
+-- @since 4.10
 eqTypeRep :: forall k1 k2 (a :: k1) (b :: k2).
              TypeRep a -> TypeRep b -> Maybe (a :~~: b)
 eqTypeRep a b