Hi,
Thank you all for you replies.
I think now I understand Haskell better.
Best regards,
Frodo
2011/10/12 Frodo Chao
Hi,
I came upon this when playing with foldr and filter. Compare the two definitions:
testr n = foldr (\x y -> x && y) True [t | (_, t) <- zip [1 .. n] [True, True ..]] testr' n = foldr (\x y -> y && x) True [t | (_, t) <- zip [1 .. n] [True, True ..]]
I tried these functions on ghci (The Glorious Glasgow Haskell Compilation System, version 7.0.3), and get the following results (with :set +s):
testr 1000000 => True (0.01 secs, 7920832 bytes) testr' 1000000 => True (8.72 secs, 446585344 bytes)
This bizarre (at least to me) behavior also applies to ||. Should I mind the orderings of the parameters (especially the accumulator) in the function passed to foldr?
Thak you for reading.
Sincerely yours, Frodo Chao