OK, I'm taking the plunge and using Haskell in a course I'm teaching this semester. To get ready, I've been doing quite a bit of Haskell programming myself, and this has raised a few questions... * What are the relative advantages of Hugs and GHC, beyond the obvious (Hugs is smaller and easier for people not named Simon to modify, while GHC is a real compiler and has the most up-to-date hacks to the type checker)? Do people generally use one or the other for everything, or are they similar enough to use Hugs at some moments and GHC at others? * As far as I can determine, there is no way to check pattern matches for exhaustiveness. Coming from OCaml, this feels like losing a significant safety net! How do people program so as not to be getting dynamic match failures all the time? * HUnit and QuickCheck seem to offer very nice -- but different -- testing facilities. Has anyone thought of combining them? (In fact, is HUnit actually used? The last revision seems to be a couple of years ago.) * I wrote a little program for generating Sierpinkski Carpets, and was astonished to find that it runs out of heap under Hugs (with standard settings -- raising the heap size with -h leads to a happier result). module Main where import SOEGraphics fillSquare w x y s = drawInWindow w (withColor Blue (polygon [(x,y), (x+s,y), (x+s,y+s), (x,y+s), (x,y)])) carpet w x y s = if s < 8 then fillSquare w x y s else let s' = s `div` 3 in do carpet w x y s' carpet w (x+s') y s' carpet w (x+s'*2) y s' carpet w x (y+s') s' carpet w (x+s'*2) (y+s') s' carpet w x (y+s'*2) s' carpet w (x+s') (y+s'*2) s' carpet w (x+s'*2) (y+s'*2) s' main = runGraphics ( do w <- openWindow "Carpet" (700,700) carpet w 50 50 600 k <- getKey w closeWindow w ) I've clearly got a lot to learn about space usage in Haskell... can someone give me a hint about what is the problem here and how it might best be corrected? Thanks for any comments, Benjamin ----------------------------------------------------------------------------- BENJAMIN C. PIERCE, Professor Dept. of Computer & Information Science University of Pennsylvania +1 215 898-2012 3330 Walnut St. Fax: +1 215 898-0587 Philadelphia, PA 19104, USA http://www.cis.upenn.edu/~bcpierce -----------------------------------------------------------------------------