#13700: GHCi command listing possible type class instances -------------------------------------+------------------------------------- Reporter: Iceland_jack | Owner: (none) Type: feature | Status: new request | Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 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: -------------------------------------+------------------------------------- This is a reminder ticket, I want to be able to list possible instances, {{{
:insts Product (Functor f, Functor g) => Functor (Product f g) (Applicative f, Applicative g) => Applicative (Product f g) ...
:insts Product Identity Functor g => Functor (Product Identity g) Applicative g => Applicative (Product Identity g) Monad g => Monad (Product Identity g) MonadFix g => MonadFix (Product Identity g) MonadZip g => MonadZip (Product Identity g) ...
:insts Product Identity Identity Functor (Product Identity Identity) Applicative (Product Identity Identity) Monad (Product Identity Identity) MonadFix (Product Identity Identity) MonadZip (Product Identity Identity) }}}
Would be so useful for `GeneralizedNewtypeDeriving` {{{#!hs newtype Pair a = P (Product Identity Identity a) deriving (Functor, Applicative, Monad, MonadFix, MonadZip, ...) -- pattern (:#) :: a -> a -> Pair a -- pattern a1 :# a2 = P (Identity a1 `Pair` Identity a2) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/13700 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler