Builtins: Should Vector's intrinsic::sort have a default "sane" comparator function?

[lth]

spec/library/Vector.html: Right now the comparefn argument to Vector's sort method is required, because its optionality on Array (with the necessity of having a cast-to-string semantics for predictability) has some problems. Since vectors are monotyped it is possible to provide a default that is saner, along these lines:

  /* T is the base type of the vector */
  function comparator(a, b) {
    if (T is Numbers) {
      if (a < b) return -1;
      if (b < a) return 1;
      return 0;
    }
    if (T is Booleans) {
      if (!a && b) return -1;
      if (a && !b) return 1;
      return 0;
    }
    if (T is Strings) {
      if (a < b) return -1;
      if (b < a) return 1;
      return 0;
    }
    /* default behavior -- from Array.sort */
    return comparator(string(a), string(b))
  }

Obviously this is optimizable as part of the Vector instantiation procedure, type dispatch does not have to happen in here. But you get the idea.

The questions are:

• Do we want a "sane" default?
• Is the above what we want?
• Are there other cases we want to worry about (eg Dates)?
• Do we want cast-to-string as the fallback, or some error behavior?