RE: Working character by character in Haskell

"Simon Marlow" writes:

...

To really match the C program, you need to use IOExts.hGetBuf and IOExts.hPutBuf, and do the operations on raw characters in memory. Using a UArray of Word8 would be better, but there aren't any operations to do IO to/from a UArray yet (actually I've written these, but they aren't in the tree yet).

So why don't getContents / putStr / etc. deforest cleanly to calls to hGetBuf and hPutBuf? I'm genuinely curious; my own experience in this direction is "The engineering is challenging". These functions are so commonly used, though---and they're vastly easier to use, actually portable, etc. The effort would surely be repaid.

I think you're right, in that the engineering would be challenging. You could conceivably factor getContents into two functions getBlocks :: IO [Block] and a pure function to unpack the blocks into characters, which would lend itself to deforestation, but that would conflict with our attempts to re-use buffers when possible. But the gains might outweigh the slight performance loss from not re-using buffers as much - it's an interesting idea, anyway. Cheers, Simon