6 Sep
2007
6 Sep
'07
2:52 p.m.
On 06/09/07, Sebastian Sylvan
foo = 2 : 3 : zipWith f (drop 1 foo) foo
There's also zipWith3 etc. for functions with more arguments.
I think this is called taking a good thing too far, but cool too: f1 u = u + 1 f2 u v = u + v f3 u v w = u + v + w -- functions renamed for consistency) zipWith1 = map zipWith2 = zipWith -- and hey presto! us1 = 3 : zipWith1 f1 us1 us2 = 2 : 3 : zipWith2 f2 (drop 1 us2) us2 us3 = 2 : 3 : 4 : zipWith3 f3 (drop 2 us3) (drop 1 us3) us3 *Main> take 10 us1 [3,4,5,6,7,8,9,10,11,12] -- integers from three upwards *Main> take 10 us2 [2,3,5,8,13,21,34,55,89,144] -- fibonacci *Main> take 10 us3 [2,3,4,9,16,29,54,99,182,335] -- what's this? Cheers, D.