simple text template

my_tt.pl

use strict;
use warnings;
use utf8;
print sub {
    my %arg = @_;
    my ($k, $v, $in) = 
	($arg{keyword}, $arg{value}, $arg{input});
    my $i = index($in, $k);
    if($i == -1) {
	return $in;
    } else { 
	do {
	    $in = $v . substr($in, $i + length($k));
	} while($i = (index($in, $k) != -1));
    }
    return $in;
}->(keyword=>'%PREFIX', value=>'/home/karronoli', input=>'%PREFIX/usr/local');