[GHC] #12107: Strange behavior of Foldable (,) a

[GHC]

#12107: Strange behavior of Foldable (,) a
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           Reporter:  polarke        |             Owner:
               Type:  bug            |            Status:  new
           Priority:  normal         |         Milestone:
          Component:  Core           |           Version:  8.0.1
  Libraries                          |
           Keywords:                 |  Operating System:  Unknown/Multiple
       Architecture:                 |   Type of failure:  Other
  Unknown/Multiple                   |
          Test Case:                 |        Blocked By:
           Blocking:                 |   Related Tickets:
Differential Rev(s):                 |         Wiki Page:
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 The definion of ''Foldable (,) a'' is as follows.

 {{{#!hs
 instance Foldable ((,) a) where
     foldMap f (_, y) = f y
     foldr f z (_, y) = f y z
 }}}

 I am very confused with this definition. As a consequence, we have
 {{{#!hs
 maximum (1,0) == 0
 }}}
 I believe this is not something we want.

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12107>
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