% This iterator splits the string on a given character,
% and returns each substring in order.
tokenize = iter (s: string, c: char) yields (string)
    while ~string$empty(s) do
        next: int := string$indexc(c, s)
        if next = 0 then
            yield(s)
            break
        else
            yield(string$substr(s, 1, next-1))
            s := string$rest(s, next+1)
        end
    end
end tokenize

start_up = proc ()
    po: stream := stream$primary_output()
    str: string := "Hello,How,Are,You,Today"

    for part: string in tokenize(str, ',') do
        stream$putl(po, part || ".")
    end
end start_up