And here's the syntactic sugar to make the invocation concise:
#!perl
use strict;
use warnings;
my $x = 1;
sub lambda
{
my $fn = pop;
my @argrefs = \(@_);
sub {
my @scopes= map { tempSet( $argrefs[$_], $_[$_] ) } 0..$#_;
&$fn;
}
}
my $y = 'Yval';
my $closure = lambda $x, $y => sub { "$x and $y" };
print $closure->($_, rand(3)), "(X=$x, Y=$y)\n" for (qw(a bitty china
+doll));
print "$x and $y\n"; # => 1
sub TempSet::DESTROY { shift(@_)->() }
sub tempSet {
my( $sv, $new )= @_;
my $prior= $$sv;
my $restore= bless
sub { $$sv= $prior },
'TempSet';
$$sv= $new;
return $restore;
}
Caution: Contents may have been coded under pressure.