[GHC] #10512: Generic instances missing for Int32, Word64 etc.

GHC ghc-devs at haskell.org
Wed May 25 04:14:02 UTC 2016


#10512: Generic instances missing for Int32, Word64 etc.
-------------------------------------+-------------------------------------
        Reporter:  andreas.abel      |                Owner:
            Type:  feature request   |               Status:  closed
        Priority:  normal            |            Milestone:
       Component:  Core Libraries    |              Version:  7.10.1
      Resolution:  wontfix           |             Keywords:  Generics
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:  #9526             |  Differential Rev(s):
       Wiki Page:                    |
-------------------------------------+-------------------------------------

Comment (by Iceland_jack):

 Seems to break example from
 [https://hackage.haskell.org/package/Chart-1.1/docs/Generics-Deriving-
 Lens.html Generics.Deriving.Lens]

 {{{
 ghci> allOf tinplate (=="Hello") (1::Int,2::Double,(),"Hello",["Hello"])

 <interactive>:85:7: error:
     • No instance for (GHC.Generics.Generic Char)
         arising from a use of ‘tinplate’
     • In the first argument of ‘allOf’, namely ‘tinplate’
       In the expression:
         allOf
           tinplate
           (== "Hello")
           (1 :: Int, 2 :: Double, (), "Hello", ["Hello"])
       In an equation for ‘it’:
           it
             = allOf
                 tinplate
                 (== "Hello")
                 (1 :: Int, 2 :: Double, (), "Hello", ["Hello"])
 }}}

 {{{
 ghci> mapMOf_ tinplate putStrLn ("hello",[(2 :: Int, "world!")])

 <interactive>:86:9: error:
     • No instance for (GHC.Generics.Generic Char)
         arising from a use of ‘tinplate’
     • In the first argument of ‘mapMOf_’, namely ‘tinplate’
       In the expression:
         mapMOf_ tinplate putStrLn ("hello", [(2 :: Int, "world!")])
       In an equation for ‘it’:
           it = mapMOf_ tinplate putStrLn ("hello", [(2 :: Int, "world!")])

 }}}

--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/10512#comment:12>
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