If you like APL, you might like one of its cousins, K.

I've written a (buggy, incomplete!) K interpreter I call oK which similarly runs in your browser: https://github.com/JohnEarnest/ok

Here's a nice little program which calculates terms of the "look-and-say" number sequence:

http://johnearnest.github.io/ok/index.html?run=%2010%7B%2C%2...

And another rather infamous example program:

http://johnearnest.github.io/ok/index.html?run=%20%7B(x%3B%2...