[Haskell-cafe] Sequence differences
nowgate at yahoo.com
Fri Apr 10 01:49:14 EDT 2009
I have a Scheme function that calculates sequence differences, i.e., it returns a sequence that is the difference between the 2nd and the 1st element, the 3rd and the 2nd, the 4th and the 3rd, etc.
(lambda (f l)
(cond ((null? (cdr l)) '())
(else (cons (f (cadr l) (car l))
(s f (cdr l)))))))
(s - '(0,1,3,6,10,15,21,28)) => (1,2,3,4,5,6,7)
I'm thinking the same function in Haskell would be something like
s f  = 
s f [x] = [x]
s f l = [ a f b | (a,b) <- zip (init l) (tail l)]
but can't figure out what the function typing would be.
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