Short arrow / lambda functions at Perl5...

arrow_lambda.pl

use v5.12;
use utf8;
use strict;
use warnings;

# to declare short arrow functions
sub Ω {
	my $in = shift;
	return sub {
		my $out = shift;
		my $old = $@;
		$@ = "";
		my $sub = eval "sub {
			my ($in) = \@_;
			return $out;
		}";
		if ($@) {
			my $err = $@;
			$@ = $old;
			return die $err;
		}
		else {
			$@ = $old;
			return $sub;
		}
	}
}

# to declare short lambdas
sub λ {
	my $str = shift;
	if ($str =~ /(.*):(.*)/) {
		my ($in, $out) = ($1, $2);
		my $old = $@;
		$@ = "";
		my $sub = eval "sub {
			my ($in) = \@_;
			return $out;
		}";
		if ($@) {
			my $err = $@;
			$@ = $old;
			return die $err;
		}
		else {
			$@ = $old;
			return $sub;
		}
	}
	return die "Bad signature!";
}

my $incr = Ω ('$x') -> ('$x + 1');
say &$incr (4); # ---> 5

say &{ λ q| $x, $y: $x + $y | } (5, 10); # ---> 15

# end of script