On Wed, Dec 21, 2005 at 07:35:28PM +0100, Peter Simons wrote:
Some example for writing a text the IO oriented way: do putStrLn "bla" replicateM 5 (putStrLn "blub") putStrLn "end"
whereas the lazy way is putStr (unlines (["bla"] ++ replicate 5 "blub" ++ ["end"]))
Um, maybe it's just me, but I think the first program is far superior to the second one. The last thing you want your I/O code to be is lazy. You want the exact opposite: you want it to be as strict as possible. Not only does the second version waste a lot of CPU time and memory for pointlessly constructing a lazily evaluated list nobody ever needs, it will also explode into your face the moment you use that approach to write any non-trivial number of bytes.
Isn't it just the usual elegance/efficiency trade-off? Personally, I would prefer the first version, unless it was not efficient enought. Actually this example is a bit too simple to show the benefits and problems of both approaches. Consider using a pretty printing library vs doing the same thing as a sequence of putStr's. Best regards Tomasz -- I am searching for a programmer who is good at least in some of [Haskell, ML, C++, Linux, FreeBSD, math] for work in Warsaw, Poland