CHIML

What is it?

CHIML (Chimera Markup Language) is a declarative dependency injection framework based on Ramda.js. CHIML allows you to build software by composing your pre-existing components (CLI programs, or JavasScript modules).

What problems does it solve?

• Spaghetti code
• Unclear error message
• Code redundancy

Who is it for?

• Developers who want to build solution by composing Javascript module and CLI programs in a declarative way using YAML.
• Developers who don't want to memorize a lot of keyword. CHIML only has 5 keywords: injection, bootstrap, component, arity, setup, parts.

Convention and Philosophy

• No global state.
• What to do instead of how to do.
• Readability matters, brevity follows.
• Currying and composition are prioritized.
• Components should be small and composable.
• Structure should be flat and sparse.

Install

npm install -g chiml

NOTE:

• You might need root privilege to install package as global.
• This package require nodejs version 10.12.0 or newer since it use module.createRequireFromPath. To install the newest stable node.js you can do the following:

sudo npm cache clean -f
sudo npm install -g n
sudo n stable
sudo npm config set scripts-prepend-node-path true

Structure

Below is the comparison between javascript and CHIML:

Javascript

// filename: cat.js
const f = require("fs");
function readFileAndShowContent(fileName) {
    writeFile(fileName).then(console.log);
}
function writeFile(fileName) {
    return new Promise((resolve, reject) => {
        f.readFile(fileName, (error, content) => {
            if (error) {
                return reject(error);
            }
            return resolve(error);
        });
    });
}
if (require.main === module) {
    const fileName = process.argv.slice[2];
    readFileAndShowContent(fileName);
}

To run the program you can do:

node cat.js ./somefile.txt

Chiml

# filename: cat.yml
injection: fs as f
bootstrap: readFileAndShowContent
component:
    readFileAndShowContent:
        setup: R.pipeP
        parts:
            - $readFile
            - $console.log
    readFile:
        setup: X.wrapNodeback
        parts: $f.readFile

To run the program you can do:

chie cat.yml ./somefile.txt

Or if you have your own library that behave like fs (i.e: Have readFile function with same signature), you can also do:

chie cat.yml ./somefile.txt --injection "./my-fs.js as f"

That's how chiml's dependency injection works. You can define the default injection, but in the runtime, you can always swap the injected components with something else. Not only useful for mocking and testing, dependency injection let you leverage the capability of your program (i.e: read from database instead of from text file).

API

By default, Chiml injects 2 Objects:

R

Ramda Js

Some notable functions are: R.pipe, R.pipeP, R.apply, R.unapply, R.init, R.last, R.head, R.tail, R.always, R.cond.

X

Chiml parser, injector, and some utilities not provided in ramda

X.invoker

Definition:

invoker: (arity: number, methodName: string, ...params: any[]) => (...args: any[]) => any;

Example:

// Example 1:

console.log("01234".slice(1)); // "1234"

const sliceFrom = X.invoker(1, "slice");
const result = sliceFrom("01234", 1);
console.log(result[0]); // "1234"
console.log(result[1]); // "01234"

// Example 2:
const player = new Player("Arthas");
player.setWeapon("Frostmourne");
player.setDamage(50);
console.log(player.attack()); // will yield something

const initPlayer = R.construct(Player as any);
const setWeapon = X.invoker(1, "setWeapon", "Frostmourne"); // parameter can be defined here
const setDamage = X.invoker(1, "setDamage"); // or later
const attack = X.invoker(0, "attack");
const initPlayerAndAttack = R.pipe(
    initPlayer,
    setWeapon,
    R.last,
    setDamage(50),
    R.last,
    attack(),
    R.head,
);
console.log(initPlayerAndAttack("Arthas")); // will yield the same thing

X.fluent

Definition:

fluent: (invokerConfigs: any[][], ...fluentParams: any[]) => (...args: any[]) => any;

Example:

const player = new Player("Arthas");
player.setWeapon("Frostmourne");
player.setDamage(50);
console.log(player.attack()); // will yield something

const initPlayer = R.construct(Player as any);
const setDamageAndDoAttack = X.fluent([
    [1, "setWeapon", "Frostmourne"], // parameter can be defined here
    [1, "setDamage"], // or later
    [0, "attack"],
]);
const initPlayerAndAttack = R.pipe(
    initPlayer,
    setDamageAndDoAttack(50),
);
console.log(initPlayerAndAttack("Arthas")); // will yield the same thing

X.initAndFluent

Definition:

initAndFluent: (configs: any[], ...params) => (...args: any[]) => any;

Example:

const player = new Player("Arthas");
player.setWeapon("Frostmourne");
player.setDamage(50);
console.log(player.attack()); // will yield something

const initPlayer = R.construct(Player as any);
const initPlayerAndAttack = X.initAndFluent([
    [1, initPlayer],
    [1, "setWeapon"],
    [1, "setDamage"],
    [0, "attack"],
]);
console.log(main("Arthas", "Frostmourne", 50)); // will yield the same thing

X.concurrent

Definition:

concurrent: (...fnList: AnyAsyncFunction[]) => AnyAsyncFunction;

Example:

function add(n1, n2) { return Promise.resolve(n1 + n2); }
function minus(n1, n2) { return Promise.resolve(n1 - n2); }

Promise.all([add(5, 4), minus(5, 4)]).then(
    (result) => console.log(result); // [9, 1]
);

const promise = X.concurrent(add, minus)(5, 4);
promise.then(
    (result) => console.log(result); // [9, 1]
);

X.wrapCommand

Definition:

wrapCommand: (stringCommand: string) => AnyAsyncFunction;

Example:

const ls = X.wrapCommand("ls ${1}");
ls("/home/").then((result) => console.log(result)); // output of `ls /home/`

X.wrapNodeback

Definition:

wrapNodeback: (fn: AnyFunction) => AnyAsyncFunction;

Example:

function addNodeback(n1, n2, cb) { cb(null, n1 + n2); }
const addPromise = X.wrapNodeback(addNodeback);
addPromise(4, 5).then((result) => console.log(result);) // 9

X.wrapNodeback

Examples

• Animal Calendar
• Microservice