purescript.md

PureScript

What is it?

• Compiles to JavaScript
• Haskell-inspired type system (with some improvements!)
• No runtime (unlike Elm, GHCJS, etc)
• A focus on readable and debuggable JavaScript

Installing

npm i -g purescript pulp

PureScript

• psc
• psci
• ...

Pulp

• pulp init
• pulp build
• pulp test
• pulp docs
• pulp server

Editor Support

Atom via psc-ide, ide-purescript, and language-purescript

git clone https://github.com/kRITZCREEK/psc-ide.git
cd psc-ide
stack install

apm install ide-purescript purescript-language

Vim and Emacs plugins too!

Let's compile some code!

x :: Number
x = 5.0

y :: Int
y = 5

import Prelude ((+))

add :: Number -> Number -> Number
add x y = x + y

import Prelude ((+))

add :: Int -> Int -> Int
add x y = x + y

data Maybe a = Nothing | Maybe a

data Maybe a = Nothing | Maybe a

greeting :: Maybe String
greeting = Just "hello."

silence :: Maybe String
silence = Nothing

type User = { name :: String
            , email :: String
            }

type Userish a = { name :: String
                 , email :: String
                 | a
                 }

import Prelude
import Control.Monad.Eff
import Control.Monad.Eff.Console

sayHi :: forall eff. Eff (console :: CONSOLE | eff) Unit
sayHi = log "hello world."

main = sayHi

data Direction
  = North
  | South
  | East
  | West

class Reversible a where
  reverse :: a -> a

instance reversibleDirection :: Reversible Direction where
  reverse North = South
  reverse South = North
  reverse East = West
  reverse West = East

mirror :: forall a. (Reversible a) => a -> Tuple a a
mirror a = Tuple a (reverse a)

Project!

• Tic-Tac-Toe -- Part 1
• Tic-Tac-Toe -- Part 2

Completed Main.purs (don't cheat!)

More stuff

• PureScript by Example (ebook by Phil Freeman)
• IRC Channel
• Pursuit -- "google (hoogle) for PureScript types and libraries"
• Recommended libraries
• Halogen and routing in PureScript
• 4 part Elm vs PureScript comparison (this eventually turns into "using the Elm Architecture in PureScript")
• PureScript Wiki - Learn
• PureScript subreddit
• QuickCheck your JavaScript!
• Haskell Programming -- great intro to FP, Haskell, and all this 'type' stuff