Manlio Perillo ha scritto:
minh thu ha scritto:
[...] The approach I suggested is a bit overkill. You can indeed use L.lines to split the input into lines then work on that.
But still, avoid the pair (Int, Bytestring). Instead, you can basically map on each line the unsafeReadInt modified to : - return the id - return if it is one kind of id or the other kind.
so : type UserId = Int type MovieId = Int unsafeReadInt :: Line -> Either MovieId UserId
Now you have a nice list [Either MovieId UserId] that you need to transform into (MovieId, [UserId]).
Thanks, this seems a much better solution.
Done: http://hpaste.org/fastcgi/hpaste.fcgi/view?id=2309 real 1m15.220s user 0m4.816s sys 0m0.308s 3084 KB memory usage Previous version required 4956 KB of memory. Thanks again for the suggestion, Minh. Manlio