### Forth

Programmed in Forth ever you have?

If you chuckled at that, the answer is probably "yes".

Forth is the programming language that makes you code the way Yoda talks. Point being, you push values on a stack and eventually execute an operation, the result of which will replace the consumed elements on the stack. The arithmetic operation `3+4*5`

could be expressed by saying `4 5 * 3 +`

(to really really honour evaluating multiplication before addition). It could equally well (and a bit more idiomatically) be expressed as `3 4 5 * +`

: `4`

and `5`

will be the topmost elements of the stack after `3 4 5`

, and `*`

takes the two topmost elements. Either way, the result will be `23`

.

This sounds appropriately nerdy, and you might wonder what the heck this is all about. The thing is, this simple convention makes for very efficient and compact implementations of the language, and it's still quite popular in embedded systems such as the Philae comet lander. If your computer runs on Open Firmware, you have a little Forth interpreter right at the bottom of your tech stack.

The Factor programming language is a direct descendant of Forth, and comes with a really powerful integrated development environment, as well as with a just-in-time compiler written in Factor itself. The IDE has executable documentation, making it similar in explorable power to Smalltalk and Mathematica.

Tags: hacking