[GHC] #8469: GHCi reports out-of-scope type family instances with :info

22 Oct 2013

      #8469: GHCi reports out-of-scope type family instances with :info
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       Reporter:  goldfire          |             Owner:
           Type:  bug               |            Status:  new
       Priority:  normal            |         Milestone:
      Component:  GHCi              |           Version:  7.7
       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 have

 {{{
 {-# LANGUAGE TypeFamilies #-}

 module A () where

 type family F a
 type instance F Int = Bool
 }}}

 {{{
 module B where

 import A
 }}}

 In GHCi:

 {{{
 Prelude> :load B
 [1 of 2] Compiling A                ( A.hs, interpreted )
 [2 of 2] Compiling B                ( B.hs, interpreted )
 Ok, modules loaded: B, A.
 *B> :i Int
 data Int = GHC.Types.I# GHC.Prim.Int#   -- Defined in ‛GHC.Types’
 <snip>
 type instance A.F Int -- Defined at A.hs:6:1
 *B>
 }}}

 This last output from `:info` should be suppressed, I would think. (I
 agree it should be printed with `:info!`.) Note the `()` in module `A`'s
 export list.

 This is a regression from 7.6.3, where the out-of-scope type family
 instance is not printed.

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8469
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