Showcase of Most Promising New Golfing Language
[What the title says.] There seem to be quite a few of these new languages that have popped up in the last year.
Nominated by Alex A.
Not only is this an interesting approach to the challenge, but it's a good display of Jelly's strengths. It doesn't use any built-ins that other golfing languages do not have, yet it beats the second best answer overall by 37% and the second best answer in a golfing language by 44%.
Nominated by Downgoat
Nominated by TanMath
Seriously is another stack-based language that can even beat CJam as it does in this answer. It has many built-ins and and cool commands. Using CP437 encoding allows for much more commands than regular ASCII.
Nominated by Seadrus
This question shows that Jolf has a lot of potential, being only three bytes shorter than the accepted answer, and would be the same length as the accepted answer, if not for a bug that was discovered. Jolf has a vast array of tools to its advantage, it's purpose being not only being mainly a golfing language but rather a utility tool; this is signified by some of it's tools that would seem to be unhelpful for regular challenges, including, but not limited to, converting back-and-forth between Greek letters and their name, a function that returns 42, and code for concatenating upper- and lower-case versions of a string.
Out of the four languages I created (and all the ones I have notes for), Retina is the only one I'd consider a golfing language. While this answer isn't a winner, it's a fairly concise solution, just barely beaten by Pyth and it showcases several of the cool things Retina can do.
Retina is perhaps a bit different from the other golfing languages in this category. It doesn't try to squeeze a ton of built-ins into single-character commands, or make use of all 256 possible byte values to squeeze in more functionality.
Instead Retina wants to do one thing: if a challenge can be solved with nothing but a regex (or a few of them), there should be as little overhead as possible in using that regex. And it does that really well, regularly beating sed and Perl when it comes to regex-only solutions.
Retina has also started to grow a bit beyond that original premise, and these days you can combine multiple types of regex stages (the answer shows transliteration, substitution and match counting), and you can loop through them (also part of that answer).
According to Doorknob's statistics, Retina is the most-used language created in 2015. And finally, here is some testimonial from undergroundmonorail:
i like seeing how much retina has evolved. iirc originally the whole language was a way to stop people from commenting "this answer is invalid, regex isn't a language" but it's so much more than that and it's kind of beautiful
05AB1E is one of the first golfing languages I made. It's not finished yet and I need to implement a lot of functions. Due to the implicit input and output, it can beat other programming languages (like Pyth, or even Jelly :p) in short trivial tasks. Of course, it's not efficient enough and I think I can improve a lot on efficiency, but I definitely think it's one of the promising languages of 2015.