[the_duke]

regex has some dependencies, though.

aho-corasick, memchr, thread_local, simd, utf8-ranges

That functionality would have to be in std.

Regex in std would sure be nice, though.

[Manishearth]

Can be in std without being exposed. libc does this IIRC; the stdlib depends on libc but doesn't expose it.

[steveklabnik]

Right, so this would be one of the questions with moving it into the actual distribution. All of that would have to be replicated in-tree and stabilized separately...