#2893: Implement "Quantified contexts" proposal -------------------------------------+------------------------------------- Reporter: porges | Owner: Type: feature request | Status: new Priority: normal | Milestone: ⊥ Component: Compiler | Version: 6.10.1 Resolution: | Keywords: proposal Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Iceland_jack): I want to mention an example from 1997: [https://www.microsoft.com/en- us/research/wp-content/uploads/1997/01/multi.pdf Type classes: an exploration of the design space]

What we really want is universal quantification:

{{{#!hs class (forall s. Monad (m s)) => StateMonad m where get :: m s s set :: s -> m s () }}}

which can be defined as {{{#!hs class ForallF Monad m => StateMonad m where get :: m s s set :: s -> m s () }}} How does it compare to `MonadState`. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/2893#comment:23 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler