[Haskell-cafe] how to print out intermediate results in a recursive function?
qiqi789 at gmail.com
Sat Feb 4 19:23:07 CET 2012
I have a question;how can I print out the intermediate number lists in a
mergesort recursive function like the following one.
merge  ys = ys
merge xs  = xs
merge (x:xs) (y:ys) = if x <= y
then x : merge xs (y:ys)
else y : merge (x:xs) ys
mergesort  = 
mergesort [x] = [x]
mergesort xs = let (as, bs) = splitAt (length xs `quot` 2) xs
in merge (mergesort as) (mergesort bs)
main = do
print $ mergesort [5,4,3,2,1]
In the main function, it only prints out the final number list. But I'd
like to print out the number lists in every recursive level. How can I
do that? Thanks.
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