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:

import "io" for File
import "./pattern" for Pattern
import "./seq" for Lst
import "./fmt" for Fmt

var p = Pattern.new("+1/s")
var lines = File.read("days_of_week.txt").split("\n").map { |l| l.trim() }
var i = 1
for (line in lines) {
    if (line == "") {
        if (i != lines.count) System.print()
    } else {
        var days = p.splitAll(line)
        if (days.count != 7) Fiber.abort("There aren't seven days in line %(i).")
        if (Lst.distinct(days).count < 7) { // implies some days have the same name
            System.print(" ∞  %(line)")
        } else {
            var len = 1
            while (true) {
                if (Lst.distinct(days.map { |d| d.take(len).join() }.toList).count == 7) {
                    Fmt.print("$2d $s", len, line)
                    break
                }
                len = len + 1
            }
        }
    }
    i = i + 1
}