nock

A small Nock interpreter written in TypeScript. Use it either:

- as an interactive REPL, or
- as a module for evaluating Nock formulas from your own code.

Install

$3

``
yarn add @tdjsnelling/nock
`

$3

`
git clone https://github.com/tdjsnelling/nock
yarn install
yarn build
yarn start:repl
`

#### What you can do in the REPL

- Paste/type a Nock expression in the bracketed, space-separated form.
- The REPL will parse it and evaluate it, printing the result.

Using as a module

The package entry point exports:
- parse(input: string) to turn a string into a Nock cell (AST/noun structure)
- the public types from types
- the interpreter functionality as default

$3

`ts
import Nock, { parse } from "nock";

const formula = parse("[42 0 1]");
const subject = formula[0]; // 42
const argument = formula[1]; // [0, 1]

const interpreter = new Nock();

const result = interpreter.nock(subject, argument);

console.log(result);
`

$3

The interpreter constructor can take some extra options:

- onHint: the function to call for the 'hint' opcode (11). Must return a noun (in which case this noun is the result of the evaluation), or null (in which case the hint acts as a side effect and normal evaluation of the operation proceeds).
- debug: enable debugging features.
- customDebug: by default, if debug is enabled, console.log is used to print helpful info during evaluation. This default behaviour can be replaced by providing a customDebug function which receives the parameters that would ordinarily be logged to the console.

`ts
const interpreter = new Nock({
onHint: (tag: Noun, clue: Noun | null, subject: Noun, argument: Cell) => Noun | null,
debug: boolean,
customDebug: (data: DebugPayload) => void,
})
`

$3

If you only need parsing (e.g., to validate or transform input), you can do:

`ts
import { parse } from "nock";

const cell = parse("[[1 2] [3 4]]");

console.log(cell);
`

$3

`ts
import { checkAtom, checkCell } from "nock";

checkAtom(42); // Ok
checkAtom([0, 1]); // Exception

checkCell(42); // Exception
checkCell([0, 1]); // Ok
`

$3

The package ships some TypeScript types:

- Atom: a natural number
- Cell: an ordered pair of nouns
- Noun: atom or cell

`ts
import type { Atom, Cell, Noun } from "nock";
``