[GHC] #14157: Flipping (give :: a -> (Given a => r) -> r) has type (r -> a -> r)
GHC
ghc-devs at haskell.org
Sat Aug 26 15:11:30 UTC 2017
#14157: Flipping (give :: a -> (Given a => r) -> r) has type (r -> a -> r)
-------------------------------------+-------------------------------------
Reporter: Iceland_jack | Owner: (none)
Type: bug | Status: new
Priority: normal | Milestone:
Component: Compiler | Version: 8.2.1
Keywords: | Operating System: Unknown/Multiple
Architecture: | Type of failure: None/Unknown
Unknown/Multiple |
Test Case: | Blocked By:
Blocking: | Related Tickets:
Differential Rev(s): | Wiki Page:
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[https://hackage.haskell.org/package/reflection-2.1.2/docs/Data-
Reflection.html#v:give give] from the ''reflection'' library has the
following type
{{{#!hs
give :: forall a r. a -> (Given a => r) -> r
}}}
but `flip give :: r -> a -> r`!
This works with our own `Given`, `give`
{{{
$ ghci -ignore-dot-ghci -XRankNTypes
GHCi, version 8.3.20170605: http://www.haskell.org/ghc/ :? for help
Prelude> class Given a
Prelude> give :: a -> (Given a => r) -> r; give = undefined
Prelude> :t flip give
flip give :: c -> a -> c
Prelude>
}}}
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/14157>
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