NAME

FP::fix -- recurse with the fix point combinator

SYNOPSIS

use FP::fix;

sub fact {
    my ($z) = @_;
    my $f = fix sub {
        my ($f,  $x, $y) = @_;
        $x > 0 ? $f->($x-1, $x*$y) : $y
    };
    $f->($z, 1)
}
is fact(5), 120;

DESCRIPTION

fix takes a function and returns another function that when called calls the original function and gives it the fix'ed function as first argument and then the original arguments.

This allows to write self-recursive local functions without having to deal with the problem of reference cycles that self-referencing closures would run into.

The example from the synopsis is equivalent to:

use Scalar::Util 'weaken';

sub fact2 {
    my ($z) = @_;
    my $f; $f = sub {
        my ($x, $y) = @_;
        $x > 0 ? $f->($x-1, $x*$y) : $y
    };
    my $_f = $f; weaken $f;
    $f->($z, 1)
}
is fact2(5), 120;

NOTE

This is alpha software! Read the status section in the package README or on the website.