[GHC] #5962: Data.Typeable: types which should compare equal don't

[GHC]

#5962: Data.Typeable: types which should compare equal don't
-----------------------------------------+----------------------------------
 Reporter:  NickSmallbone                |          Owner:                  
     Type:  bug                          |         Status:  new             
 Priority:  normal                       |      Component:  libraries/base  
  Version:  7.4.1                        |       Keywords:                  
       Os:  Unknown/Multiple             |   Architecture:  Unknown/Multiple
  Failure:  Incorrect result at runtime  |       Testcase:                  
Blockedby:                               |       Blocking:                  
  Related:                               |  
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 Here are two ways to construct a TypeRep for the type () -> ():

 {{{
 Prelude> import Data.Typeable
 Prelude Data.Typeable> let unitToUnit = typeOf (\() -> ())
 Prelude Data.Typeable> let unitToUnit' = mkFunTy (typeOf ()) (typeOf ())
 }}}

 It seems to work:

 {{{
 Prelude Data.Typeable> unitToUnit
 () -> ()
 Prelude Data.Typeable> unitToUnit'
 () -> ()
 }}}

 But the two TypeReps are not equal:

 {{{
 Prelude Data.Typeable> unitToUnit == unitToUnit'
 False
 }}}

-- 
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5962>
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