I don't really care if the function is called chop or not.
But in many cases it is used to chop a list into smaller pieces.
On Tue, Dec 14, 2010 at 12:00 AM, wren ng thornton
On 12/13/10 12:17 PM, Lennart Augustsson wrote:
I would like to propose the following function for inclusion in Data.List
chop :: ([a] -> (b, [a])) -> [a] -> [b] chop _ [] = [] chop f as = b : chop f as' where (b, as') = f as
It's commonly occuring recursion pattern. Typically chop is called with some function that will consume an initial prefix of the list and produce a value and the rest of the list.
The function is clearly related to unfoldr, but I find it more convenient to use in a lot of cases.
It's also deeply related to iteratees (for the obvious enumerator of a list). The major difference is that iteratees enforce that the consuming function must return a tail of the input stream, whereas this function doesn't require that at all (for both good and ill).
The name "chop" seems a bit strange to me, but other than that it's a nice function.
-- Live well, ~wren
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