Hello, I was thinking about using haskell to do some 'realtime' audio signal processing, and am trying to figure out how close to the holy grail of "C" code I can get when it comes to speed. Currently, it looks like I might be looking at running 10 times slower. Is there stuff I could do to get better performance out of haskell? In example 1, I create an unitialized 1.8MB array of type 'IOUArray Int Word8', and write it to a file. This takes a mere 0.056 seconds (on an Athlon 600). module Main where import Data.Array import Data.Array.IO import System.IO main = do h <- openBinaryFile "test.b" WriteMode a <- newArray_ (1,1800000) hPutArray h a 1800000 In example 2, I apply a filter to the array (in this case, the filter is just the id function). This takes around 1.06 seconds. main = do h <- openBinaryFile "test.b" WriteMode a <- newArray_ (1,1800000) b <- mapArray id a hPutArray h b 1800000 If I apply the 'filter' twice, the time increases to 2.58 seconds: main = do h <- openBinaryFile "test.b" WriteMode a <- newArray_ (1,1800000) b <- mapArray id a c <- mapArray id b hPutArray h c 1800000 By comparison, the following c program runs in 0.10 seconds: #include <stdio.h> int main (int argc, char *argv[]) { FILE *fp; char *a; char *b; int i; a = (char *)malloc (1800000); b = (char *)malloc (1800000); for (i = 0; i < 1800000; i++) { b[i] = a[i]; } fp = fopen("test.b","w"); fwrite(b, 1, 1800000, fp); fclose(fp); free(b); free(a); return 0; } I compile using ghc from cvs as follows: ghc -O2 -fvia-C Test.hs -o test I also tried just -O, and no -fvia-C, and the performance was the same. Without -O, it was about 5 times slower. I compiled the c code with: gcc -O2 test.c -o test. I am using ghc from cvs head and gcc 2.95 on FreeBSD. Are there secret options I should enable on the compiler? Or perhaps there is a faster way than using mapArray and unboxed arrays? Thanks! Jeremy Shaw.