@fpjs/overture/bin/repl.js

A Javascript prelude

#!/usr/bin/env node

// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

import fs from "fs";
import path from "path";
import repl from "repl";

const die = (msg, exitCode=1) => {
    process.stderr.write(msg + "\n", "utf-8");
    process.exit(exitCode);
};

const profile = (s, n=10000) => (f) => {
    console.time(s);
    try {
        for (let i = 0; i < n-1; i++) {
            f();
        }
        return f();
    } finally {
        console.timeEnd(s);
    }
};

const findModules = (dir) => {
    let modules = [];

    for (const file of fs.readdirSync(dir, {withFileTypes: true})) {
        if (file.isDirectory()) {
            modules = modules.concat(findModules(path.join(dir, file.name)));
        } else if (file.isFile()) {
            modules.push(path.resolve(path.join(dir, file.name)));
        }
    };
    return modules;
};

const npmModuleFromExec = (exec) => {
    const {root, dir} = path.parse (exec);

    const findNpmModule = (dir) => {
        if (dir === root) {
            die(`${exec} is not located inside an NPM module`);
        }
        if (fs.existsSync (path.join (dir, "package.json"))) {
            return dir;
        }
        return findNpmModule (path.dirname (dir));
    };

    return findNpmModule (fs.realpathSync (exec));
};

const main = async () => {
    const [_node, overture, ...args] = process.argv;
    const overtureModule = npmModuleFromExec (overture);

    const r = repl.start({
        ignoreUndefined: true,
        prompt: 'λ ',
        replMode: repl.REPL_MODE_STRICT,
        useGlobal: true,
    });

    const modules = await Promise.all(
        findModules(path.join(overtureModule, "./src"))
            .map((module) => import(module))
    );
    Object.assign(
        r.context,
        ...modules,
        { profile },
    );
    r.context.patchBuiltins();
}

main();