Re: [GHC] #8002: Type family causing GHC to hang on recompilation

21 Jun 2013

      #8002: Type family causing GHC to hang on recompilation
-----------------------------+----------------------------------------------
Reporter:  jweijers          |          Owner:                  
    Type:  bug               |         Status:  new             
Priority:  normal            |      Component:  Compiler        
 Version:  7.6.3             |       Keywords:                  
      Os:  Unknown/Multiple  |   Architecture:  Unknown/Multiple
 Failure:  None/Unknown      |      Blockedby:                  
Blocking:                    |        Related:                  
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Comment(by monoidal):

 Here is a simplified version, with three modules Generics.hs, A.hs, B.hs:

 {{{
 {-# LANGUAGE TypeFamilies #-}
 module Generics where

 type family Rep a
 type instance Rep Int = Int
 }}}

 {{{
 {-# LANGUAGE UndecidableInstances #-}
 {-# LANGUAGE TypeFamilies #-}

 module A where

 import Generics

 class QA a where
   type QRep a
   type QRep a = QRep (Maybe a)

 instance QA () where
   type QRep () = ()
 }}}

 {{{
 {-# LANGUAGE TypeFamilies #-}
 module B where

 import A
 }}}

-- 
Ticket URL: http://hackage.haskell.org/trac/ghc/ticket/8002#comment:1
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