Strict<->Lazy?

[Richard A. O'Keefe]

	fib :: Int -> Int
	fib 0 = 0
	fib 1 = 1
	fib n = fib (n-1)+fib(n-2)
	
Er, fib 0 is ONE, not ZERO.

	This took my computer about 21.5 seconds to calaculate the 40-th
	number.

I haven't cared to try fib(40) because I'm using an 84MHz machine
and fib(35) is already interesting.  Interestingly, this definition
took 6.8 seconds for fib(35), whereas 
	fib n = if (n < 2) 1 (fib (n-1) + fib (n-2))
took 5.7 seconds.

	But when rewriting the algorithm to
	
	fib2 :: Int -> Int
	fib2 n = fibList !! n
	where
	  fibList = [0,1:[i+j \\ i <- fibList & j <- tl fibList]]
	
	the computing time became negligible.

Yes, but that is a DIFFERENT ALGORITHM (also computing non-Fibs thanks
to the 0 that should have been 1); the same algorithm can be used in C
to speed the C version up too.  For the record, fib(40) took so long
in C that I didn't bother to wait for it.