My body was clearly not ready to do regex research again. I was adding in slashes like I was in a horror flick until I finally just tried putting the darn i where it belonged

nicely done !

ah! of course! Thankyou! Quite elegant, actually!

i did like that <3

case insensitive regex.
it will match both upper and lowercase vowels.

Nice and elegant!

Really nice solution, just one thing.
I guess it is not a good practice to use the pipe operator just for one pipe.
https://github.com/christopheradams/elixir_style_guide#avoid-single-pipelines

Pretty neat solution you've comed up with.

map_join very cool feature

You people should really look at the kyu of this kata. It is meant to introduce enumerables to beginners. There are higher kyu katas that explicitly disable native methods to teach other concepts. This is not one of them.

Actually, shouldn't it be ["123"]?

This answer is incorrect.