README.md

PureScript Language Reference

As an introductory example, here is the usual "Hello World" written in PureScript:

module Main where

import Control.Monad.Eff.Console

main = log "Hello, World!"

Another Example

The following code defines a Person data type and a function to generate a string representation for a Person:

data Person = Person { name :: String, age :: Int }

showPerson :: Person -> String
showPerson (Person o) = o.name <> ", aged " <> show o.age

examplePerson :: Person
examplePerson = Person { name: "Bonnie", age: 26 }

Line by line, this reads as follows:

• Person is a data type with one constructor, also called Person
• The Person constructor takes an object with two properties, name which is a String, and age which is an Int
• The showPerson function takes a Person and returns a String
• showPerson works by case analysis on its argument, first matching the constructor Person and then using string concatenation and object accessors to return its result.
• examplePerson is a Person object, made with the Person constructor and given the String "Bonnie" for the name value and the Int 26 for the age value.

The full language reference continues below:

1. Types
2. Syntax
3. Type Classes
4. Pattern Matching
5. Modules
6. FFI
7. Records
8. Differences from Haskell