[Haskell-cafe] Re: IO Put confusion

15 Sep 2010


      Chad Scherrer  writes:
...
Second attempt:
doc :: IO Put
doc = docLength >>= go
  where
  go 1 = word
  go n = do
    w <- word
    ws <- go (n-1)
    return (w >> putSpace >> ws)
This one actually works, but it holds onto everything in memory
instead of outputting as it goes. If docLength tends to be large, this
leads to big problems.
Sorry to answer my own post, but I've got a kludgy work-around now. I tried a 
WriterT approach, and also building my own "PutT" like Data.Binary.Put, neither 
with any luck. Instead I just changed the type to
word, doc :: IO ()
and had it write standard out as is goes. Not nearly as elegant, but at least it 
works now.

Thanks,
Chad