procedure main(A)
    ll := integer(A[1]) | 72
    wordWrap(&input, ll)
end

procedure wordWrap(f, ll)
    every (sep := "", s := "", w := words(f)) do
       if w == "\n" then write(1(.s, s := sep := ""),"\n")
       else if (*s + *w) >= ll then write(1(.s, s := w, sep := " "))
                               else (s ||:= .sep||("\n" ~== w), sep := " ")
    if *s > 0 then write(s)
end

procedure words(f)
    static wc
    initial wc := &cset -- ' \t'   # Loose definition of a 'word'...
    while l := !f do {
        l ? while tab(upto(wc)) do suspend tab(many(wc))\1
        if *trim(l) = 0 then suspend "\n"   # Paragraph boundary
        }
end