Problem Statement

The use of   abbreviations   (also sometimes called synonyms, nicknames, AKAs, or aliases)   can be an easy way to add flexibility when specifying or using commands, sub─commands, options, etc.

It would make a list of words easier to maintain   (as words are added, changed, and/or deleted)   if the minimum abbreviation length of that list could be automatically (programmatically) determined.

For this task, use the list (below) of the days-of-the-week names that are expressed in about a hundred languages   (note that there is a blank line in the list). Caveat:   The list (above) most surely contains errors (or, at the least, differences) of what the actual (or true) names for the days-of-the-week.

To make this Rosetta Code task page as small as possible, if processing the complete list, read the days-of-the-week from a file (that is created from the above list).

Notes concerning the above list of words

Let's start with the solution:

use strict;
use utf8;
binmode STDOUT, ":utf8";

sub auto_abbreviate {
    my($string) = @_;
    my @words = split ' ', $string;
    my $max = 0;
    return '' unless @words;
    map { $max = length($_) if length($_) > $max } @words;
    for $i (1..$max) {
        my %seen;
        return $i if @words == grep {!$seen{substr($_,0,$i)}++} @words;
    }
    return '∞';
}

open $fh, '<:encoding(UTF-8)', 'DoWAKA.txt';
while ($_ = <$fh>) {
    print "$.) " . auto_abbreviate($_) . '  ' . $_;
}