PureScript

Description #

PureScript is a strongly-typed, purely functional language that compiles to JavaScript, making it ideal for building robust front-end and back-end web applications. It offers Haskell-like syntax, powerful type inference, and safe functional programming in the JavaScript ecosystem.

History #

PureScript was created by Phil Freeman and released in 2013. It was developed to bring Haskell-style programming to JavaScript while focusing on simplicity and compatibility with modern tooling.

Key milestones:

• Inspired by Haskell but designed to generate clean JS
• Emphasizes type safety, purity, and expressiveness
• Frequently used with frameworks like Halogen and React
• Gained traction among functional programming enthusiasts building typed web apps

Hello World Code #

module Main where

import Effect.Console (log)
import Effect (Effect)

main :: Effect Unit
main = log "Hello, World!"

How to Run #

Online: #

• Use Try PureScript
• Paste the code and click Run

Locally: #

1. Install PureScript:

npm install -g purescript spago

Create a new project:

spago init

Replace src/Main.purs with the code above

Build and run:

spago run

Key Concepts #

• main :: Effect Unit — entry point with explicit side effect type
• log — prints to the console from the Effect.Console module
• Pure functions — no side effects unless declared
• Strong static types — prevents runtime errors
• Type inference — compiler often figures out types for you
• Algebraic data types — build complex but safe data models
• Module system — clean, dependency-aware organization
• Interop with JS — use and write JavaScript from PureScript
• Composable architecture — functional patterns for reusability
• Compiles to readable JavaScript — easy to debug and optimize

Try It Online #

🔗 Try PureScript
🔗 Replit – PureScript
🔗 PureScript Book Site

Fun Facts #

• PureScript was created to solve JavaScript complexity with Haskell-style safety
• Its generated JavaScript is often more readable than code from TypeScript
• PureScript supports FFI (foreign function interface) for integrating JS libraries
• PureScript developers often write fewer lines of code for the same logic
• Halogen, a PureScript UI framework, is one of the most type-safe UI libraries available

Resources #

PureScript GitHub Repo

PureScript Official Site

PureScript by Example (Book)

Awesome PureScript GitHub