On Sun, 7 Feb 2016 at 17:16 Richard Eisenberg <eir@cis.upenn.edu> wrote:

I would agree with this... except that the version of ($) in base in 7.8 and 7.10 already *was* generalized in this way. But no one got as itchy about the OpenKind that appears in 7.10's `:i $` as they are about the guck that appears in 8.0's `:t ($)`. So moving it out now would break code in the wild like https://ghc.haskell.org/trac/ghc/ticket/8739

My GHC 7.10 doesn't seem to have any OpenKind stuff:

GHCi, version 7.10.3: http://www.haskell.org/ghc/ :? for help
Prelude> :i $
($) :: (a -> b) -> a -> b -- Defined in ‘GHC.Base’
infixr 0 $