// pred: func(S) -> bool
static L<S> mapLike splitAtLinePredicate(O pred, S text) {
  L<S> lines = toLines(text);
  new L<S> l;
  int i = 0;
  while (i < l(lines)) {
    int j = i;
    while (j < l(lines) && !callPred(pred, lines.get(j)))
      ++j;
    if (j > i)
      l.add(joinLines(lines.subList(i, j)));
    i = j+1;
  }
  ret l;
}

Began life as a copy of #1003804