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Getting Started

CARMI is a build time tool that transforms a Directed Acyclic Graph of derivations and setters into the source code of an optimized function that calculates your derivations/computed-state and maintains them as long as you change your model only using the setters you defined.

Phil Karlton - "There are only two hard things in Computer Science: cache invalidation and naming things"

I can't help you much with naming stuff (although you tend to name significantly fewer things in CARMI as you just let the data flow from one derivation to the next) - but I sure hope you'll never have to think of cache invalidation again.

Install Carmi using yarn:

yarn add --dev carmi

or npm:

npm install --save-dev carmi

Create your first model

/// model.carmi.js
const { root, arg0, setter } = require('carmi');
const model = {
  doubled: root.map(item => item.mult(2)),
  setItem: setter(arg0)
};
module.exports = model;

CLI usage

npx carmi --source ./model.carmi.js --output ./model.js --format cjs

Configure webpack

Add the Carmi loader to the list of modules within your webpack configuration object:

module: {
  rules: [
    {
      test: /\.carmi.js$/,
      exclude: /(node_modules|bower_components)/,
      use: {
        loader: 'carmi/loader'
      }
    }
  ];
}

/// you can load your generated code either via using a babel loader / a webpack plugin,
/// or by simply adding a build step to generate the source
const modelFunction = require('./model.carmi');
const instance = modelFunction([1, 2, 3, 4]);
// each property defined on the model object generates either a derived value or a setter
console.log(instance.doubled);
// prints [2,4,6,8]
instance.setItem(0, 10);
console.log(instance.doubled);
// prints [20,4,6,8]
Derived state →