recursive-grammar-literal

Specify a context-free grammar using recursive functions in ordinary javascript.

Instead of writing something like:

E -> A '+' A   { $0 + $1 }
A -> '(' E ')'
A -> number

you can write:

function exp() {
    let left = addExp();
    readToken("+");
    let right = addExp();
    return left + right;
}

function addExp() {
    return oneOf(
        parenExp, 
        inline(() => readToken("number"))
    );
}

function parenExp() {
    readToken("(");
    let result = exp();
    readToken(")");
    return result;
}

The output is a context-free grammar using an ADT defined using church-cat. This isn't directly useful unless you are working on a parser or structure editor or something. ll-parser.js contains a simple LL parser which uses the resulting grammar to actually parse something, and example.js shows a full example of building a JSON grammar, parsing it with ll-parser, and extracting the computed javascript value.

Read more at https://jasonhpriestley.com/23-1-25-recursive-grammar-literals