My questions about 'any' and 'all' really had more to do with pedagogy than anything else, but now that I got GHC figured out, I ran some tests using their profiler. I used version 4.08 on FreeBSD 4.2 and did not enable optimization. I called the function 'atLeastOne' instead of 'any' just to make sure I didn't confuse myself. Prelude Version --------------- GHC's default 'any' and 'or' differ from the Prelude specification, so I wrote the equivalent versions by hand.

default (Int)

main = print (atLeastOne (> 1000000) [0..999999])

atLeastOne :: (a -> Bool) -> [a] -> Bool atLeastOne p = foldr (||) False . map p

Here are the results: Tue Jan 23 16:01 2001 Time and Allocation Profiling Report (Final) foo +RTS -p -RTS total time = 1.16 secs (58 ticks @ 20 ms) total alloc = 88,001,188 bytes (excludes profiling overheads) COST CENTRE MODULE %time %alloc atLeastOne Main 63.8 54.5 main Main 36.2 45.5 SYSTEM MAIN 17.2 0.1 Total allocation due to atLeastOne: 0.545 * 88001188 = 47,960,647 bytes Recursive Version ----------------- I wrote 'atLeastOne' by hand so that it wouldn't use GHC's builtin version, which has rewrite rules that may allow better optimization.

default (Int)

main = print (atLeastOne (> 1000000) [0..999999])

atLeastOne :: (a -> Bool) -> [a] -> Bool atLeastOne _ [] = False atLeastOne p (x:xs) = p x || atLeastOne p xs

Here are the results: Tue Jan 23 16:01 2001 Time and Allocation Profiling Report (Final) bar +RTS -p -RTS total time = 0.76 secs (38 ticks @ 20 ms) total alloc = 64,001,096 bytes (excludes profiling overheads) COST CENTRE MODULE %time %alloc atLeastOne Main 71.1 37.5 SYSTEM MAIN 39.5 0.2 main Main 28.9 62.5 Total allocation due to atLeastOne: 0.375 * 64001096 = 24,000,411 bytes Summary ------- I realize that this is not a perfect test, but it does say something. To those who read my previous post, when I said that 'any' takes linear space, I meant in the worst case. And as Tom Pledger pointed out to me privately via email, all of that space immediately becomes garbage, so it may not be fair to count it against the space requirements of the program. However, it does take time to reclaim it. Thanks to all who replied. -- Dr. Eric Shade, Associate Professor Computer Science Department (CSAB Accredited) Southwest Missouri State University