Relationship to North

North (Nock Forth) is a Forth interpreter for Nock by ~lagrev-nocfep, aiming for broad ANSI-Standard-flavored Forth compatibility while adapting memory-bound features to Nock’s noun model. Forth is a concatenative, stack-based language: words consume and produce values on a shared data stack, definitions compose by juxtaposition, and the interpreter and compiler are simple enough to bootstrap from a few hundred lines of primitives.

North runs interactively as a REPL on a live Urbit ship and can be driven from a Jupyter notebook via Jupytur, demonstrating that stack-based concatenative languages map cleanly onto a Nock host.

North is written in Hoon as a standalone library and runs as a Gall %shoe agent on an Urbit ship, providing a persistent REPL with the usual Forth state: data stack, return stack, dictionary, input buffer, and compile/interpret mode. North supports stack and arithmetic operators, control flow, defining words (CREATE/DOES>), counted loops, exceptions (CATCH/THROW), strings, CASE/OF/ENDOF/ENDCASE, and IMMEDIATE words.

North’s relationship to Nock is indirect: Forth source executes through a Hoon-written interpreter, which itself compiles to Nock.

Example

A North session at the dojo REPL:

2 3 + .         \ prints 5
: SQUARE DUP * ;
5 SQUARE .      \ prints 25

: SQUARE DUP * ; adds an entry to the dictionary with body DUP *.

Further Reading

• North GitHub Repository: Hoon implementation, test suite, and Gall agent.