Am Mittwoch 17 Februar 2010 16:31:16 schrieb Sean Leather:
I find myself often writing this pattern:
someFun x y z = ...
fun y z = runFun $ someFun someDefault y z
or, alternatively:
fun y = runFun . someFun someDefault y
The second option approaches the ideal pointfreeness (or pointlessness if you prefer), but I'd like to go farther:
(...) :: (c -> d) -> (a -> b -> c) -> a -> b -> d
(...) f g x y = f (g x y)
(...) = (.) . (.)
infixr 9 ...
fun = runFun ... someFun someDefault
There, that's better. More points for fewer points (which means I should really change the name from fun to pun).
Does anybody else care about this? What are some alternative solutions?
o = (.) oo = (.) . (.) ooo = (.) . (.) . (.) -- etc. runFun `oo` someFun someDefault I've also seen (.:) = (.) . (.) runFun .: someFun someDefault I don't particularly like (...), it's too much like an ellipsis (and bad to count if you continue on that route), I prefer the 'spectacles' or (∘) = (.) (∘∘) = (.) . (.)
I'd love to have something like this available in the Prelude or a library. (I have no strong feelings about the particular operator.)
Regards, Sean