readme.md

Forthkit

Inspired by Lispkit, build your own Forth from scratch.

0. Write an interpreter (in Python). Similar to Chuck Moore's first punch card interpreter.
1. Play with it!
   • Write a console Pixel library (in Forth) using Unicode Braille characters
   • Use this to do turtle graphics (in Forth)!
2. Make register-based "hardware" (VM in C) and assembler (in Forth)
3. Use the assembler to build a kernel (a bytecode image using Forth)
4. Abandon the Python interpreter and bootstrap Forth to the new "hardware"
   • Port pixel library to this
   • Port turtle graphics to this (using fixed point)
   • Port kernel itself to this
   • Achieve meta-circularity! That is, build the kernel using Python, then use that kernel to build a new (identical for now) kernel. Iterate.
   • TODO: re-write kernel in more natural Forth syntax
   • TODO: Fill out the vocabulary to support the standard core words
5. TODO: Build an inner interpreter and take away call/ret from the "hardware"
   • TODO: Experiment with direct/indirect threading
   • TODO: Experiment with using the return stack for locals and loop counters
   • TODO: Implement remaining Forth control structures
   • TODO: Explain does> in the context of direct/indirect threading
   • TODO: Discuss/implement token threading
   • TODO: Discuss separate headers (e.g. fall-through definitions, save memory, ...)
   • TODO: Discuss separate host/target (like Brief)
6. TODO: Make more new "hardware" - a stack machine this time
7. TODO: Port our Forth to this - see how the inner interpreter goes away
   • TODO: Use block-style disk I/O
8. TODO: Move to a colorForth style variant (less syntax, no immediate words, etc.)
9. TODO: Build a block editor and stop using Vim
   • TODO: We've now bootstrapped a whole "OS" for ourselves!
10. TODO: Discuss non-standard ideas:
    • Quotations ([: ... :]), combinators, (Factor, Joy, Brief, ...)
    • if as a combinator
    • Recursion as only control flow
11. TODO: Discuss other execution models (e.g. stack/continuation, XY, Brief, ...)
12. TODO: More ideas
    • VT100 library
    • Snake game
    • Tetris game
    • Discuss optimizing compilation