Jason Rametta Blog

Pratica, now fully in Typescript!

October 18, 2019

Pratica is now written completely in Typescript!

What is Pratica?

Pratica is a super tiny 720B monadic library, comparable to Crocks or Monet JS.

Why would I use Pratica?

If you want to start writing more functional code in Javascript or Typescript, this is a great library for learning some FP fundamentals, while also making your code safer and more resilient to runtime bugs. It’s super tiny size and easy to read dot-chaining syntax makes it easy to get started in any project.

How do I start?

You can install it with: yarn add pratica or npm i pratica. Then you can import the main functions like:

import { nullable } from 'pratica'

Create small, safe and easy to read programs by composing functions together, like:

// Typescript

import { Maybe, nullable, get, parseDate } from 'pratica'

const getPersonAge = (person?: Person): Maybe<number> =>
  nullable(person)
    .chain(get<string>(['birthday']))
    .chain(parseDate)
    .map(birthday => Date.now() - birthday.getTime())
    .chain(parseDate)
    .map(date => Math.abs(date.getUTCFullYear() - 1970))


getPersonAge({ birthday: '1994-06-08' }) // -> Just(25)
getPersonAge({ birthday: 771033600000  }) // -> Just(25)
getPersonAge({ birthday: null }) // -> Nothing
getPersonAge(null) // -> Nothing

Pratica works great with React too! Use it in your JSX for handling cases with missing data.

const viewPersonAge = ({ person }) =>
  getPersonAge(person).cata({
    Just: age => <div>{age}</div>
    Nothing: () => <span>No age available</span>
  })

Try it out

Try it out in an online browser sandbox here!


Jason Rametta

Written by Jason Rametta who lives and works in Montreal building useful things. You should follow him on Twitter