Just because we *can* extend the core SML `List` signature, that doesn't
mean we *should*. It's a neat trick, but it makes it harder to find uses
of the new modules, and obfuscates definitions for very little gain.
The SML standard library is pretty bare-bones compared to that of other
functional languages, so in a large enough SML project you end up with a
bunch of reimplementations of basic combinators scattered all over the
place. We'd be able to collect them if we had somewhere to collect them,
so here it is.
Edward Pierzchalski
Corey Lewis