John Mann wrote:
> Hello, I am working my way through Simon Thompson's
> Haskell book, and one exercise has me baffled. That is
> "how would you define the "length" function using
> "map" and "sum" "? Any help on this would be
> appreciated.
Create a list of 1's of the same length as the input list (with map),
then compute its sum (with sum).
i.e.:
length = sum . map (const 1)
or:
length l = sum (map (const 1) l)
or:
length l = sum (map (\x -> 1) l)
--
Glynn Clements <[EMAIL PROTECTED]>
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