Forth can be interpreted but it can also be compiled in at least two or three different ways. Forth is unique in that its interpreter can look (and perform) a l

Forth can be interpreted but it can also be compiled in at least two or three different ways. Forth is unique in that its interpreter can look (and perform) a lot like compiled code. Let's say you have a list of assembly language function names FOO, BAR, BAZ, etc. Each name stands for the starting memory address of that function. Each function ends with a standard RET instruction. At address PROGRAM, you store the list of 64-bit function addresses. Now a "Forth Interpreter" is just JSR-INDIRECT RP++ REPEAT where beforehand you've stashed PROGRAM in register RP. Most assemblers don't provide an indirect JSR instruction but it's easy to write a macro that serves that purpose. Is this an interpreter? The only way it differs from true compiled code is that the function calls are indirect, so it's almost as fast as regular function calls. What if you unroll the thing so the code looks like JSR FOO JSR BAR JSR BAZ ... Now all the function calls are direct. And as a bonus, all the individual functions themselves don't have to do anything more special than directly call functions. It's turtles all the way down. I've glossed over some issues like how to pass values and how many stacks you need and proactive tail-calling, but that's the gist of it. The whole "interpreter" just vanishes in a puff of smoke.