31 Jul
2009
31 Jul
'09
2:26 a.m.
On Fri, Jul 31, 2009 at 5:53 AM, Ryan Ingram
Read ($) as a parenthesis that extends as far to the right as possible; so you can write, for example:
That doesn't always work, for example : map (+2) . map (*1) $ [1,2,3] = [4,6,8] Now replacing the $ by a parenthesis that extends as far to the right as possible : map (+2) . map (*1) ( [1,2,3] ) <interactive>:1:11: Couldn't match expected type `a -> [a1]' against inferred type `[a2]' In the second argument of `(.)', namely `map (* 2) ([1, 2, 3])' In the expression: map (+ 2) . map (* 2) ([1, 2, 3]) In the definition of `it': it = map (+ 2) . map (* 2) ([1, 2, 3])