On 05/13/2010 01:22 PM, bearophile wrote:
Pelle:
It is stored as a list, and is in effect memoized.<
In practice I think Haskell doesn't memoize things there. I think it optimizes
most things away. The main point of pure generators is indeed that they give
the compiler enough guarantees (just as pure functions) that allow it to
perform those optimizations safely. The point of my original post is that I'd
like a way to give the D compiler such semantic information, mostly for
optimization purposes (but there are other purposes, similarly to the purposes
of pure functions).
Yes, it does. Try it!
Prelude> let fibs = 1 : 1 : zipWith (+) fibs (tail fibs)
Prelude> fibs !! 80000
... some time passes, a huge number appears.
Prelude> fibs !! 80000
... almost instantly, the same number.
Edit the 80000 to a large enough number to slow your system down.
Note that all numbers below the large number chosen is very fast as
well, once the large calculation is done.
