++ed by:
RPAVLOV JGAMBLE

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1 non-PAUSE user.

Christian Jaeger
and 1 contributors

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;