Join functions

[evinism]

Can imagine:

join.left
join.right
join.outer
join.inner

[cfilipov]

You have a join function which is used for concatenating strings with a separator which I feel can be confusing with the relational joins proposed. Maybe the existing join should be concat or something?

[evinism]

yeah, that naming conflict has definitely been a concern of mine for a bit -- i opted for join as the inverse of split, but that might have been a poor long-term choice. I like concat though!

I also think now is the right time to correct this -- if i don't it's going to be very annoying to correct in the future.