[GHC] #10564: GHC 7.10.2 RC cannot build HList-0.4.0.0

23 Jun 2015


      #10564: GHC 7.10.2 RC cannot build HList-0.4.0.0
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              Reporter:  snoyberg    |             Owner:
                  Type:  bug         |            Status:  new
              Priority:  normal      |         Milestone:  7.10.2
             Component:  Compiler    |           Version:  7.10.2-rc1
              Keywords:              |  Operating System:  Linux
          Architecture:  x86_64      |   Type of failure:  GHC rejects
  (amd64)                            |  valid program
             Test Case:              |        Blocked By:
              Blocking:              |   Related Tickets:
Differential Revisions:              |
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 Another Stackage find:

 http://lpaste.net/135061

 {{{
 Data/HList/Record.hs:575:10:
     Illegal instance declaration for ‘HasFieldM l (r xs) v’
       The liberal coverage condition fails in class ‘HasFieldM’
         for functional dependency: ‘l r -> v’
       Reason: lhs types ‘l’, ‘r xs’ do not jointly determine rhs type ‘v’
     In the instance declaration for ‘HasFieldM l (r xs) v’

 Data/HList/Record.hs:587:10:
     Illegal instance declaration for
       ‘HasField l (Record (Tagged l1 v1 : r)) v’
       The liberal coverage condition fails in class ‘HasField’
         for functional dependency: ‘l r -> v’
       Reason: lhs types ‘l’, ‘Record (Tagged l1 v1 : r)’
         do not jointly determine rhs type ‘v’
     In the instance declaration for
       ‘HasField l (Record (Tagged l1 v1 : r)) v’

 Data/HList/Record.hs:646:10:
     Illegal instance declaration for ‘HDeleteAtLabel Record l v v'’
       The liberal coverage condition fails in class ‘HDeleteAtLabel’
         for functional dependency: ‘l v -> v'’
       Reason: lhs types ‘l’, ‘v’ do not jointly determine rhs type ‘v'’
     In the instance declaration for ‘HDeleteAtLabel Record l v v'’

 Data/HList/Record.hs:723:10:
     Illegal instance declaration for
       ‘HUpdateAtLabel2 l v (Tagged l' e : xs) xs'’
       The liberal coverage condition fails in class ‘HUpdateAtLabel2’
         for functional dependency: ‘l r v -> r'’
       Reason: lhs types ‘l’, ‘Tagged l' e : xs’, ‘v’
         do not jointly determine rhs type ‘xs'’
     In the instance declaration for
       ‘HUpdateAtLabel2 l v (Tagged l' e : xs) xs'’
 }}}

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Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10564
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