Hello Bas, Tuesday, October 24, 2006, 1:03:55 AM, you wrote:
Great it works! I didn't know about unsafeInterleaveIO [1]. Why is it called 'unsafe'? And how does the laziness work? Is it because of the 'let r = ... in (s, r)'?
read either http://haskell.org/haskellwiki/IO_inside or Simon's paper "awkward squad" mentioned there in your original program, parseFile don't parsed file. it just returned thunk (computation) that will parse file when data from this thunk will be requested. so, your mapM returned 18k of such thunks, each with its own file open. Tomasz's solution postpone not only parsing, but the whole parseFile call (including file open) until the data from this parsing will be really requested. because your next code uses results of each parsing before using results of next one, this allows garbage collector to close files of already used parsings before you go to consume next one. smart solution -- Best regards, Bulat mailto:Bulat.Ziganshin@gmail.com