#!/usr/bin/perl -w
package Do_notation;

use strict;
use Filter::Simple;

my $lhs = qr{(.*)}s;
my $rhs = qr{(.*)}s;
my $lambda = qr{$lhs <- $rhs}x;
my $do_term = qr[DO.*?{(.*?)}]s;

FILTER {
            s/$do_term/fix_it($1)/esg
        };

                    
### code only has problems with parsing perl (no surprises)
#FILTER_ONLY code => sub {s/$do_term/fix_it($1)/esg };

sub fix_it
{
	my $exception = chr(28);
	#print STDERR $_[0]; print STDERR "XXXXXXX\n";
    (my $strip_newlines = $_[0]) =~ s/\n+(?!$exception)//g;
	my @statements = split /;/, $strip_newlines;
	my @new_front; my @new_back;
	
	for (@statements)
	{
		if(m/$lambda/)
		{
			push @new_front, "Bind($2)->(sub{$1=shift;\n"; 
			unshift @new_back, "})";
		}
		elsif(m/(.*)/)
		{
			push @new_front, $1;
			push @new_front, "\n";
		}
		else { die "syntax error\n"; }
	}
	#print STDERR join "",(@new_front,@new_back,""); print STDERR "------------\n";	
	return join "",(@new_front,@new_back,"");
}

1;