[GHC] #13038: implementation of Modus ponens and Modus tollens
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ghc-devs at haskell.org
Sat Apr 22 15:42:39 UTC 2017
#13038: implementation of Modus ponens and Modus tollens
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Reporter: vanto | Owner: (none)
Type: feature request | Status: infoneeded
Priority: normal | Milestone:
Component: libraries/base | Version: 8.0.1
Resolution: | Keywords:
Operating System: Unknown/Multiple | Architecture:
| Unknown/Multiple
Type of failure: None/Unknown | Test Case:
Blocked By: | Blocking:
Related Tickets: | Differential Rev(s):
Wiki Page: |
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Comment (by Iceland_jack):
Regarding adding `implies` (`(==>)`),
[https://ghc.haskell.org/trac/ghc/ticket/10592#comment:12 here is the
hierarchy] I'm most intrigued by
{{{#!hs
class Boolean (Logic a) => Eq a where
type Logic a :: Type
(==) :: a -> a -> Logic a
class Eq a => POrd a where
inf :: a -> a -> a
class POrd a => MinBound a where
minBound :: a
class POrd a => Lattice a where
sup :: a -> a -> a
class (Lattice a, MinBound a) => Bounded a where
maxBound :: a
class Bounded a => Complemented a where
not :: a -> a
class Bounded a => Heyting a where
infixr 3 ==>
(==>) :: a -> a -> a
class (Complemented a, Heyting a) => Boolean a
}}}
--
Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/13038#comment:6>
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