Memoized fibonacci in Raku

fib.raku

#!/usr/bin/env raku
use v6;

sub memoize-walk (Code $calc --> Code) {
    my Int @cache;

    return sub (Int $n --> Int) {
	    return @cache[$n] if @cache[$n];

	    my Int $result = $calc($n);

	    @cache[$n] = $result;
    }
}

my Code $fib = memoize-walk sub (Int $n --> Int) {
    return 1 if $n < 2;

    return $fib($n - 1) + $fib($n - 2);
}

sub MAIN (Int $n = 33) {
    say $fib($n);
}