Warren's Abstract Machine: A Tutorial Reconstruction (1999)
16 points by hwayne
16 points by hwayne
This is an amazing resource. I have a hard copy, and implementing it step-by-step was what made me really get Prolog and logic programming in general. If anyone has been bouncing off traditional resources trying to learn Prolog, I’d highly recommend working through this in your most familiar language. Working from the bottom up mechanics of the interpreter really builds an intuition if top-down learning isn’t working.
The WAM was a Prolog abstract machine that was, at least in the 80’s and 90’s, an intermediate target for prolog compilers. Don’t know if that’s still true.
Scryer, GNU and SICStus use WAM (each one their own version). SWI uses ZIP, which is a bit different but not that much. It is said that the best VM is TOAM, which features jumbo instructions, but it’s not well documented, only B-Prolog and Picat use it. Of course, you can also implement Prolog without an intermediate abstract machine, with continuations for example.