On Wednesday 18 July 2007 21:16, Johan Tibell wrote:
It would be nice if it was possible to capture this kind of behavior in a high order function just like map though. I guess the problem is that the function to map will take different number of arguments depending on the use case.
lookAtTwo a b = ...
lookAtThree a b c = ...
map' :: (a -> ... -> b) -> [a] -> [b]
The parameter take a variable number of parameters.
Note: I don't know if there is a sensible way to write map' at all. Perhaps explicit recursion is better in this case.
Oleg (unsurprisingly) has some type-class hackery for polyvariadic/keyword functions. Probably do what you need, possibly be overkill for what you want... here it is anyway. http://okmij.org/ftp/Haskell/keyword-arguments.lhs