An experiment in building a Forth interpreter in Hoon, targeting the Nock/Urbit runtime. The long-term goal is a self-hosting Forth that compiles to Nock nouns.
North aims for broad ANSI Standard Forth compatibility, adapting features like memory management to the noun-based Nock model where appropriate.
North runs as a Gall %shoe agent on an Urbit ship. After installing the desk,
connect to the REPL from the dojo:
|link %north
Then type Forth expressions at the > prompt:
2 3 + . \ prints 5
: SQUARE DUP * ;
5 SQUARE . \ prints 25
SON \ enable stack display
10 20 + \ prints ok ~[30]
SOFF \ disable stack displayErrors are caught and displayed as ! <message> without crashing the agent.
- Architecture — state structure, eval loop, token IR, tier progression
- Word Reference — all implemented Forth words with stack effects
- Design Notes — open questions (memory model, Nock-native addressing)
- Deep Dive — comprehensive design research
desk/
lib/north.hoon — interpreter: types, tokenizer, eval loop (~1000 lines)
app/north.hoon — Gall %shoe REPL agent
tests/
test-north.sh — shell test harness (~270 tests, 0 failures through Tier 17)
docs/
architecture.md — architecture overview
words.md — word reference
WORKING.md — design notes
nock-forth-deep-dive.md
DPANS94.txt — ANSI Forth standard
lbForth.c — reference C implementation
- Tiers 0–9: stack ops, arithmetic, bitwise, return stack, memory, dictionary, interpreter core, compilation, text parser
- Tiers 10–12: full ANSI word set, DO/LOOP counted loops, VARIABLE/CONSTANT/RECURSE
- Tiers 13–15: output words,
[]LITERAL, CREATE/DOES> defining words - Tiers 16–17: CATCH/THROW exceptions, S"/." string literals, CASE/OF/ENDOF/ENDCASE
- Tier 18: Gall
%shoeREPL agent with persistent state, SON/SOFF stack display
- Tier 19:
WORD— parse tokens from the input stream - Tier 20:
IMMEDIATE— mark words as compile-time immediate - Tier 21+: Nock code generation — emit Nock nouns from Forth definitions