import peggyParser from "./PeggyParser.js";

export type Application = {
  application: {
    left: LambdaTerm;
    args: Array<LambdaTerm>;
  };
};

export type Abstraction = {
  abstraction: {
    param: Variable;
    body: LambdaTerm;
  };
};

export type Variable = string;

export type LambdaTerm = Application | Abstraction | Variable;

export const isApplication = (term: LambdaTerm): term is Application => {
  return (term as Application).application !== undefined;
};

export const isAbstraction = (term: LambdaTerm): term is Abstraction => {
  return (term as Abstraction).abstraction !== undefined;
};

export const isVariable = (term: LambdaTerm): term is Variable => {
  return typeof term === "string";
};

export const parse = (term: string, library = false) => {
  return peggyParser.parse(term, { peg$library: library });
};