Tom Ellis
On Sat, Feb 06, 2016 at 01:27:00PM +0100, Ben Gamari wrote:
The first (albeit rather unconvincing) example I can think of is be something like,
getI# :: Int -> Int# getI# (I# n#) = n#
n# :: Int# n# = getI# $ 5 + 8
Richard likely has something a bit less contrived though.
I hope there's something less contrived, because if the benefit is "you get to use $ to apply functions whose return type is not of kind *" then the power to weight ratio of this is extremely low.
Is it also something to do with the special treatment that $ gets in the compiler, to allow 'runST $ do'?
https://www.mail-archive.com/glasgow-haskell-users@haskell.org/msg18923.html
To this the best of my knowledge, no. This would require impredicative polymorphism which Richard's work does not provide. There is (was?), however, active work on this front as well [1]. Cheers, - Ben [1] https://ghc.haskell.org/trac/ghc/wiki/ImpredicativePolymorphism/Impredicativ...