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

#12107: Strange behavior of Foldable (,) a -------------------------------------+------------------------------------- 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: -------------------------------------+------------------------------------- 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. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12107 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#12107: Strange behavior of Foldable (,) a -------------------------------------+------------------------------------- Reporter: polarke | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Core Libraries | Version: 8.0.1 Resolution: wontfix | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by thomie): * status: new => closed * resolution: => wontfix Comment: This has been discussed to death already: * https://mail.haskell.org/pipermail/libraries/2016-February/026678.html * https://mail.haskell.org/pipermail/libraries/2016-March/026851.html * https://www.reddit.com/r/haskell/comments/3oq0kd/proposal_eliminate_the_mona... * https://www.reddit.com/r/haskell/comments/3pfg7x/either_and_in_haskell_are_n... Closing as wontfix, until there is consensus to remove the instance from the libraries list or the Core Libraries Committee. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12107#comment:1 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler

#12107: Strange behavior of Foldable (,) a -------------------------------------+------------------------------------- Reporter: polarke | Owner: Type: bug | Status: closed Priority: normal | Milestone: Component: Core Libraries | Version: 8.0.1 Resolution: wontfix | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Other | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by polarke): Thx for clearing! Replying to [comment:1 thomie]:
This has been discussed to death already: * https://mail.haskell.org/pipermail/libraries/2016-February/026678.html * https://mail.haskell.org/pipermail/libraries/2016-March/026851.html *
* https://www.reddit.com/r/haskell/comments/3pfg7x/either_and_in_haskell_are_n...
Closing as wontfix, until there is consensus to remove the instance from
https://www.reddit.com/r/haskell/comments/3oq0kd/proposal_eliminate_the_mona... the libraries list or the Core Libraries Committee. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12107#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler
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