Type safe Option and Result type

Inspired by Rust.

Previously known on npm as tsp-monads.

!Codecov
 

NOTE: Works with TypeScript 2+ _and_ JavaScript (ES6+). strictNullChecks option / flag strongly recommended.

Documentation

- Option Type
- Result Type

Install

``
npm install @threestup/monads
`

Basic Usage

`typescript
import { Option, Some, None } from '@threestup/monads'

const divide = (numerator: number, denominator: number): Option => {
if (denominator === 0) {
return None
} else {
return Some(numerator / denominator)
}
};

// The return value of the function is an option
const result = divide(2.0, 3.0)

// Pattern match to retrieve the value
const message = result.match({
some: res => Result: ${res},
none: 'Cannot divide by 0',
})

console.log(message) // 'Result: 0.6666666666666666'
`

`typescript
import { Result, Ok, Err } from '@threestup/monads'

function getIndex(values: string[], value: string): Result {
const index = values.indexOf(value)

switch (index) {
case -1:
return Err('Value not found')
default:
return Ok(index)
}
}

console.log(getIndex(['a', 'b', 'c'], 'b')) // Ok(1)
console.log(getIndex(['a', 'b', 'c'], 'z')) // Err('Value not found')
...
``

Documentation

- Option Type
- Result Type