split l-o-n into chunks of consecutive numbers areas

gistfile1.hs

-- http://stackoverflow.com/questions/10368835/partitioning-a-list-in-racket

foldr (\x r-> case r of [] -> [[x]]; ((a:_):_) | x+1 /= a -> [x]:r; (b:c) -> ((x:b):c)) []

-- or, MUCH preferred, TRMC:
foldr (\x r-> let (b:c)=case r of {[] -> [[]]; ((a:_):_) | x+1 /= a -> []:r; _ -> r} in ((x:b):c)) []

--  [1,2,3,5,6,8,9]  ==>  [[1,2,3],[5,6],[8,9]]

http://programmingpraxis.com/2015/08/25/collect-sets-of-ranges