RE: [Hugs-users] Avoiding use of the stack

-----Original Message----- From: ajb@spamcop.net Sent: den 20 november 2004 14:19 To: hugs-users@haskell.org Subject: RE: [Hugs-users] Avoiding use of the stack

G'day all.

Quoting Josef Svenningsson :

...

In what sense is it wrong, and in what sense does this example show that?

The time that you want to use $! is when you want some argument to some function to be strict. Unfortunately, $! and $ have different associativities to normal function application, requiring you to introduce readability-imparing parentheses if the strict argument is not the last one:

testR2' a n = (testR2' $! (a+n)) (n-1)

If $! and $ were both left-associative, you could write this instead:

testR2' a n = testR2' $! (a+n) $ (n-1)

Ah, you're quite right of course. This surely must be a bug in the report. Cheers, /Josef