I often wish that cool tricks like this could be collected on the Haskell web site. Now that it's a wiki, anyone could do that. Simon | -----Original Message----- | From: haskell-prime-bounces@haskell.org [mailto:haskell-prime-bounces@haskell.org] On Behalf Of | oleg@pobox.com | Sent: 15 March 2006 04:34 | To: doaitse@cs.uu.nl; haskell-prime@haskell.org | Subject: Infix expressions | | | Doaitse Swierstra wrote: | > In Haskell we write `f` in order to infixify the identifier f. In ABC | > the stuff between backquotes is not limited to an identifier, but any | > expression may occur there. This would allow one to write e.g. | > | > xs `zipWith (+)` ys | | Chung-chieh Shan and Dylan Thurston showed the Haskell98 solution for | exactly the same example, in their article `Infix expressions', | back in 2002: | http://www.haskell.org/pipermail/haskell-cafe/2002-July/003215.html | | For ease of reference, here's their elegant solution: | | > infixr 0 -:, :- | > data Infix f y = f :- y | > x -:f:- y = x `f` y | > | > main = print $ [1,2,3] -: zipWith (+) :- [4,5,6] | | | For completeness, here's the `dual': | | > infixr 5 -! | > (-!) = flip ($) | > infixr 5 !- | > (!-) = ($) | > | > add2 x y = x + y | > add3 x y z = x + y + z | > add4 x y z u = x + y + z + u | > | > testa1 = 1 -! add2 !- 3 + 4 | > testa2 = 1 -! add3 1 !- 3 + 4 | > testa3 = 1 - 2 -! add4 1 5 !- 3 * 4 | | All code is Haskell98. | _______________________________________________ | Haskell-prime mailing list | Haskell-prime@haskell.org | http://haskell.org/mailman/listinfo/haskell-prime