PureScript Conf 2016

1. Getting Started with
PureScript
John A. De Goes

2. Agenda
• Introduction
• What is PureScript
• Syntax & Semantics
• Who Uses PureScript
• Why PureScript
• Ecosystem
• Getting Started
• Node.js
• NPM
• Bower
• PureScript
• Pulp
• Hello World

3. What is PureScript?
PureScript is a strongly-typed, purely-functional programming
language that compiles to Javascript1
, and is written in and
inspired by Haskell.
1
And C++!

4. Syntax
import Control.Apply
import Graphics.Canvas.Free
scene =
filled $ closed do
moveTo 0 0
lineTo 50 0
lineTo 25 50
where
closed path = beginPath *> path <* closePath
filled shape = shape <* fill

5. Semantics
• Type Inference
• Higher-Kinded Polymorphism
• Support for basic Javascript types
• Extensible records
• Extensible effects
• Optimizer rules for generation of efficient Javascript
• Pattern matching
• Simple FFI
• Modules
• Rank N Types
• Do Notation
• Tail-call elimination
• Type Classes

6. Who Uses PureScript?2
• SlamData
• Xamarin
• DICOM Grid
• Middlebury Interactive Languages
• DICE.fm
• McGraw Hill Financial
2
Cobbled together from various online sources.*

7. Why PureScript?
Motivation
• You want to or are forced to do front-end or node.js
• You like static typing
• You like functional programming, of the pure variety
• You prefer expressive power over no-frills, opinionated simplicity
• You want to crush Javascript/CoffeeScript/TypeScript/Scala3
beneath your
heel... BWAHAHA!
3
OK, not quite yet.

8. Why PureScript?
..instead of GHCJS?
• "Haskell in hindsight"
• Strict versus lazy
• Zero runtime
• Clean, easy FFI
• Great re-use of third-party JS
• Simpler language than GHC's quadrillion dialects of Haskell

9. Ecosystem

10. Ecosystem
UI Libraries
• purescript-halogen
• purescript-react
• purescript-angular
• purescript-rx
• purescript-flare
• purescript-pux
• purescript-optic-ui
• purescript-behaviors
• purescript-signal
• purescript-thermite
• purescript-frp-rabbit
• purescript-sigment
• purescript-ufi
And even more!

11. Ecosystem
Testing Libraries
• purescript-test-unit
• purescript-quickcheck
• purescript-quickcheck-laws
• purescript-strongcheck
• purescript-benchotron
• purescript-spec
• purescript-assert

12. Ecosystem
Preludes4
• purescript-prelude
• purescript-preface
• purescript-batteries
4
Yes, there are multiple!

13. Ecosystem
Build Tooling
• pulp
• grunt-purescript
• gulp-purescript
• purescript-psa

14. Ecosystem
Editor / IDE Support
• Atom
• purescript-contrib/atom-language-purescript
• nwolverson/atom-ide-purescript
• Emacs
• dysinger/purescript-mode
• emacs-pe/purescript-mode
• ardumont/psci-mode
• spion/purscheck
• emacs-pe/flycheck-purescript
• epost/psc-ide-emacs
• Sublime Text 2 - PureScript package
• Vim
• purescript-vim
• FrigoEU/psc-ide-vim
• IntelliJ IDEA - ikarienator/pure-idea
• Visual Studio - nwolverson/vscode-ide-purescript
• General
• kRITZCREEK/psc-ide
• To generate TAGS files, use psc-docs --format etags (or --format ctags)

15. Ecosystem
Library Search
Pursuit

16. Getting Started
Prerequisites
1. Node.js
2. NPM
3. Bower
4. PureScript
5. Pulp

17. Getting Started
Prerequisites: Node.js
Node.js® is a JavaScript runtime built on Chrome's V8 JavaScript
engine. Node.js uses an event-driven, non-blocking I/O model
that makes it lightweight and efficient. Node.js' package
ecosystem, npm, is the largest ecosystem of open source libraries
in the world.
Node.js allows full-featured, browser-less Javascript
programs.

18. Getting Started
Prerequisites: Node.js
• Many Javascript dev tools are written in Javascript and run
on Node.js
• PureScript dev tools are written in PureScript, compiled to
JavaScript
• Bottom Line: You can't live without it (even if you want to!).

19. Getting Started
Prerequisites: Node.js
• Installers
https://nodejs.org/en/download/
• Homebrew
brew install node
• MacPorts
port install nodejs
• pkgsrc
pkgin -y install nodejs
• Debian / Ubunutu (4.x)
curl -sL https://deb.nodesource.com/setup_4.x | sudo -E bash -
sudo apt-get install -y nodejs
• Debian / Ubuntu (6.x)
curl -sL https://deb.nodesource.com/setup_6.x | sudo -E bash -
sudo apt-get install -y nodejs

20. Getting Started
Prerequisites: NPM
• NPM = Node Package Manager
• Used by Node to manage packages
• Many tools and libraries are distributed through NPM
• Bottom Line: Another thing you can't live without...

21. Getting Started
Prerequisites: NPM
• NPM comes pre-installed with Node.js but version may be
old
• Self-Updating NPM:
sudo npm install npm -g

22. Getting Started
Prerequisites: Bower
• A package manager for the web
• Maintains global registry of name -> URL
• Supports repositories & tags
• Supports all types of dependencies (binary, PureScript, etc.)
• Dependencies specified in bower.json file
• Bottom Line: Almost all PureScript libraries are registered with bower,
and almost all PureScript projects maintain dependencies with bower!

23. Getting Started
Prerequisites: Bower
{
"name": "purescript-library",
"description": "A PureScript library",
"authors": [
"John A. De Goes <john@degoes.net>"
],
"license": "Apache 2",
"version": "0.1.0",
"ignore": [
"**/.*",
"node_modules",
"bower_components",
"output"
],
"dependencies": {
"purescript-profunctor-lenses": "^1.0.0-rc.1",
"purescript-free": "^1.0.0-rc.1",
"purescript-console": "^v1.0.0-rc.1",
"purescript-either": "^v1.0.0-rc.1",
"purescript-maybe": "^1.0.0-rc.1",
"purescript-foldable-traversable": "^1.0.0-rc.1",
"purescript-monoid": "^1.0.0-rc.2",
"purescript-bifunctors": "^1.0.0-rc.1",
"purescript-invariant": "^1.0.0-rc.1",
"purescript-prelude": "^1.0.0-rc.4",
"purescript-control": "^1.0.0-rc.1",
"purescript-transformers": "^1.0.0-rc.1"
}
}

24. Getting Started
Prerequisites: Bower
• Install with NPM
npm install -g bower

25. Getting Started
Prerequisites: PureScript Compiler
• psc — PureScript compiler
• psc-docs — PureScript documentation generator
• psc-bundle — Bundler & dead-code eliminator
• psci — PureScript Read-Eval-Print-Loop (REPL)
• psc-ide-server — IDE Server
• psc-ide-client — IDE Client

26. Getting Started
Prerequisites: PureScript Compiler
• Installers
https://github.com/purescript/purescript/releases/latest
• Install with NPM
npm install -g purescript

27. Getting Started
Prerequisites: Pulp
• Pulp: Popular build tool for PureScript projects
• Knows how to perform magical incantations of psc & related
tools
• Bottom Line: If you can use it to build your project, then do
it!

28. Getting Started
Prerequisites: Pulp
• Install with NPM
npm install -g pulp

29. Getting Started
Hello World
1. Create Directory Structure
2. Create Bower File
3. Install Bower Dependencies
4. Write PureScript Main
5. Build & Run

30. Getting Started
Hello World: Create Directory Structure
bower.json
/src/
/Main.purs

31. Getting Started
Hello World: Create Bower File
{
"name": "hello world",
"dependencies": {
"purescript-console": "^0.1.1",
"purescript-eff": "^0.1.2",
"purescript-prelude": "^0.1.5"
}
}

32. Getting Started
Hello World: Install Bower Dependencies
bower install

33. Getting Started
Hello World: Write PureScript Main
module Main where
import Prelude(Unit)
import Control.Monad.Eff (Eff)
import Control.Monad.Eff.Console (CONSOLE, log)
main :: forall e. Eff (console :: CONSOLE | e) Unit
main = do
log "Hello World!"

34. Getting Started
Hello World: Build & Run
pulp build
pulp run

35. Congratulations, You've Started Your Journey Into The
World of PureScript!
Don't Forget the Easy Peasy PureScript Workshop at LambdaConf 2016!
More Resources: http://purescript.org

36. THE END