Gwion Preprocessor

Memoization

You can use the memoize pragma to enable memoization on functions:

normal version

fib_recurs.gw

fun int recursive_fib(int n) {
    if (n < 2)
        return n;
    return recursive_fib(n - 2) + recursive_fib(n - 1);
}
<<< 40 => recursive_fib >>>;

memoized version

The syntax of the memoize pragma is as follow:

#pragma memoization <number of results to store>

See the memoized version of previous function:

fib_recurs_memoize.gw

fun int recursive_fib(int n) {
#pragma memoize 2
    if (n < 2)
        return n;
    return recursive_fib(n - 2) + recursive_fib(n - 1);
}
<<< 40 => recursive_fib >>>;

Under circomstance where memoization is applicable, such as this one, you can see a huge speed-up.

normal:

memoized:

Memoization setting will be active until the end of file or until it is changed. Therefore, if you want to disable memoization for subsequent functions, use:

#pragma memoize 0