bs-big.js

Bucklescript bindings to big.js, a library for arbitrary-precision decimal arithmetic. All methods are supported.

Installation

1. Make sure big.js is installed: npm install big.js
2. Install the bindings: npm install bs-big.js
3. Add the bindings to bs-config.json:

{
  "bs-dependencies": [
      "bs-big.js"
  ]
}

Usage

Big numbers of type Big.t can be created using Big.fromInt, Big.fromString or Big.fromFloat. Arithmetic can then be done using the pipe-first |. syntax. For example:

Big.setDP(10); //set decimal places
Big.setRM(1); //set rounding mode
let x = Big.fromInt(2);
let y = Big.fromInt(3);
let z = x |. Big.div(y);
let _ = z |. Big.toString // "0.6666666667"
let _ = z |. Big.sqrt |. Big.toString // "0.8164965809"
let _ = z |. Big.pow(-3) |. Big.toString // "3.3749999995"
let _ = z |. Big.times(z) |. Big.toString // "0.44444444448888888889"
let _ = z |. Big.times(z) |. Big.round(~dp=10, ()) |. Big.toString // "0.4444444445"

Documentation

See Big.mli and the big.js documentation

Testing

Very extensive testing was done by porting most of the tests from big.js. To run the tests:

npm test

Things to note

• The methodBig.mod_ has an underscore because mod is a reserved keyword in OCaml/Reason
• The last parameter of all methods with optional parameters is unit. This is because the last parameter would be optional, which don't work properly in OCaml. Keeping the parameter order allows consistent use of the pipe-first syntax |., so it is better to end with unit than swap order.
• OCaml does not have -0 but Javascript does