do  -- Abbreviatiions automatic - find the minimum abbreviation lengths for days of the week
    --                            in various languages

    require( "uchar" )         -- RC Pluto Unicode character library

    -- returns the table of space delimited words in s
    local function getWords( s : string ) : table
        local t, cmds, w = s, {}, s
        while t:contains( " " ) do
            w, t = t:partition( " " )
            if w != "" then
                cmds[ # cmds + 1 ] = w
            end
        end
        if t != "" then
            cmds[ # cmds + 1 ] = t
        end
        return cmds
    end

    for dow in io.lines( "daysOfWeekNames.txt" ) do
        local names <const> = getWords( dow )
        if # names == 0 then
            io.write( "\n" )
        elseif # names != 7 then
            error( dow .. ": expected 7 names" )
        elseif # names > 0 then
            -- try abbreviation lengths up to the minimum word length
            local maxLen, uName = -1, {}
            for i, n in ipairs( names ) do
                uName[ i ] = uchar.of( n )
                local thisLen <const> = uName[ i ]:len()
                if thisLen > maxLen then
                    maxLen = thisLen
                end
            end
            local found = false
            for abLen = 1, maxLen do
                local prefixes <const> = {}
                found = true
                for nPos = 1, # names do
                    local subLen <const> = if uName[ nPos ]:len() < abLen
                                           then uName[ nPos ]:len()
                                           else abLen
                                           end
                    local ab <const>     = uName[ nPos ]:sub( 1, subLen )
                    if prefixes:contains( ab ) then
                        found = false
                        break
                    else
                        prefixes[ ab ] = ab
                    end
                end
                if found then
                    io.write( string.format( "%2d %s\n", abLen, dow ) )
                    break
                end
            end
            if not found then
                error( "No unique abbreviations for: " .. dow )
            end
        end
    end

end