Hal Daume III wrote:
BTW, I already found a major problem with the code I attached earlier, using unsafeInterleaveIO: Run in GHCi (as I had done), it works fine; but compiled by GHC and run as an executable, it waits for input and *then* displays the prompt after the user hits Enter ... not very helpful. I didn't think it would do that, since (putStr "? " >> readLn) seemed pretty explicit as to order of evaluation, but I guess that's what I get for breaking referential transparency ...
You probably want to set the buffering otherwise. [...]
Ah, you're right ... I changed (putStr "? " >> readLn) to (putStr "? "
hFlush stdout >> readLn) and it worked.
So is this lazy-stream-via-unsafeInterleaveIO not so nasty, then, so long as a few precautions (not reading too far into the stream, accounting for buffering, etc.) are taken? I like the idiom Hudak uses (passing a stream of I/O results to the purely functional part of the program), so if it's kosher enough I'd like to get hacking elsewhere ... Luke Maurer jyrinx_list@mindspring.com