I was just going to post about this. In Graham's early essay on succinct languages, he asks, "Are there languages that force you to write code in a way that is crabbed and incomprehensible?"
Factor feels incomprehensible until you learn to hold the stack in your head. The result is you eliminate all the intermediate variables in a program, which makes the language extremely succinct. All that's left are function calls and control-flow, which you can't remove anyway.
I believe the key to succinctness is (1) minimal boilerplate, (2) higher-order functions and (3) reducing intermediate variables. Functional languages achieve (3) with function composition. But Factor (and Forth et al) goes way beyond what functional languages can do.
Locals are a pain. Who needs locals when you can keep multiple values on the stack and keep them there.
Factor is to FORTH like Java is to C.
because of FORTH's nature it's essentially lisp without parenthesis.
On the other hand Java is about as powerful as C with training wheels.
