On Fri, Feb 19, 2010 at 10:42 PM, wren ng thornton <w...@freegeek.org> wrote: > Sean Leather wrote: >> >> 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 ... > > I go with infixl 8 personally. It seems to play better with some of the > other composition combinators. > > In a somewhat different vein than Oleg's proposed general composition, I've > particularly enjoyed Matt Hellige's pointless fun combinators[0]. I have a > version which also adds a strict application combinator in my desiderata > package[1] so we can say things like: > > foo $:: bar ~> baz !~> bif > > which translates to: > > \a b -> bif (foo (bar a) (baz $! b)) > > These combinators are especially good when you don't just have a linear > chain of functions. >
Thanks! I'm glad to know that people have found this approach useful. In cases where it works, I find it somewhat cleaner than families of combinators with (what I find to be) rather obscure names, or much worse, impenetrable sections of (.). We can write the original example in this style: fun = someFun someDefault $:: id ~> id ~> runFun but unfortunately, while it's both pointfree and fairly clear, it isn't really an improvement over the pointful version, IMHO. Matt _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
