finlambda

finlambda

Is a JavaScript library for financial calculations designed to be used with functional programing paradigm.

It uses Ramda.

Why finlambda

Build your custom calculator for taxes, compose it easily using ramda.

finlambda allows write your business rules easy to understand, easy to change and without side effects.

Installation

npm install finlambda ramda@0.26.0

Node

Import all functions

const FinLambda = require('finlambda')

or individually

const { rateAt } = require('finlambda')

ES2015 or typescript

import { rateAt } from 'finlambda'

Browser

<script src="path/to/yourCopyOf/ramda.js></script>
<script src="path/to/yourCopyOf/finlambda.js></script>

Usage

create a complex tax

const bracket15 = taxBracket(rateAt(0.15), forInterval(0, 38120))
const bracket28 = taxBracket(rateAt(0.28), forInterval(38121))
const brackets = [bracket15, bracket28]
const corpTax = tax(brackets);
const afterCorpTax = netAfter(corpTax)
// calculate your tax
corpTax(100000)        //=> 23045
// calculate net amount after tax
afterCorpTax(100000)   //=> 76955

chain taxes

const flatTax = rateAt(0.30)
const afterFlatTax = netAfter(flatTax)

const withFlatTax = R.pipe(afterCorpTax, afterFlatTax)

withFlatTax(100000) //=> 53868.5

tax value in each bracket

const coprTaxDetailed = taxDetail(brackets)
corpTaxDetailed(100000) //=> [ 5718, 11726.12 ]

Read all documentation here