[GHC] #8535: :info (->) doesn't print all relevant instances

14 Nov 2013


      #8535: :info (->) doesn't print all relevant instances
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       Reporter:  parcs             |             Owner:
           Type:  bug               |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  GHCi              |           Version:  7.6.3
       Keywords:                    |  Operating System:  Unknown/Multiple
   Architecture:  Unknown/Multiple  |   Type of failure:  None/Unknown
     Difficulty:  Unknown           |         Test Case:
     Blocked By:                    |          Blocking:
Related Tickets:                    |
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 I noticed that ":info (->)" does not does not print all relevant
 instances, specifically instances whose heads use `->` in an infix way.
 For example,

 {{{
 $ ghci -v0
 Prelude> import Data.Monoid
 Prelude Data.Monoid> :i (->)
 data (->) a b   -- Defined in `GHC.Prim'
 instance Monad ((->) r) -- Defined in `GHC.Base'
 instance Functor ((->) r) -- Defined in `GHC.Base'
 Prelude Data.Monoid>
 }}}

 The instance `Monoid b => Monoid (a -> b)` is not printed.

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8535
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