Developer experience is important and Clojure developers have the pleasure of managing their build process in Clojure with Leiningen.org

1. Leiningen 2
Humane build
management for
ClojureMadeSimple.co.uk

2. slideshare.net/jr0cket
This slide deck is available to follow along with on slideshare.net

5. of Java build
management

6. ...there was Ant,
Ant begat Ivy,
Ant begat Maven

7. … and there was much XML all around

12. build
management

13. Human verses Computer readable build jobs

14. Leiningen
… more fun than Maven
… easy way to kick-start your Clojure
addiction

15. Leiningen: Manual install
Download the Leiningen 2 install script from
leiningen.org
Move the lein file to an executable location, eg.
~/bin
Make the install script executable and run the install
chmod u+x ~/bin/lein
lein

16. Leiningen: package managers
● Ubuntu
● Debian
● Fedora
● CentOS

17. Leiningen
also staring in
Eclipse plugin
Counter Clockwise

18. All the usual tasks...
lein new ● Create a new clojure project
lein deps ● Download all dependencies
lein run ● Run your application
lein jar ● Deploy your app as a jar

19. ...and then some
lein uberjar - Include Clojure & all your
dependencies in one jar
lein repl - Fire up the dynamic coding
environment (REPL)
- Hook to start a REPL from
jack-in within Emacs

20. Fire up the REPL
REPL: read, evaluate, print loop – dynamic
lein repl environment for Clojure and other lisps

21. Typing code into the REPL
Develop functions and data structures on the fly
REPL: read, evaluate, print loop – dynamic environment for Clojure and other lisps

22. Create a new project
lein new my-project
cd my-project
lein deps
Lein deps will check your project.clj configuration file and
download any libraries (jar files) that are required by the project

23. Anatomy of a new project
Note: dashes in project names are converted to
underscores to make Java happy!

24. Over-riding defaults

25. Create project with a different
template
lein new
template-name
my-project

26. Example: WebNoir template
lein new noir fpdays2012-web

27. Version your project with Git
cd my-project
git init
Create a repo on github & add it to your project
git remote add origin
git@github.com/account/project.git
git push -u origin master
You may want to edit your .git-ignore file also

28. Open project in emacs
cd my-project
emacs project.clj

29. project.clj - project definition
Lein deps will check this project.clj configuration file and
download any libraries (jar files) that are required by the project

30. Group Dependencies
Usually a reversed domain name

31. Dev Dependencies
Dev-dependencies: Add libraries only needed for
development, not packaged when code deployed

32. https://clojars.org/

33. http://search.maven.com

34. Add a REPL session
REPL: read, evaluate, print, loop – dynamic environment for Clojure
and other lisps

35. Add REPL session to all projects
~/.lein/profiles.clj

36. Fire up the REPL in Emacs
M – x
clojure-
jack-in
M – x represents the keyboard combination of the meta key followed by x.
Then the command clojure-jack-in is entered.

37. REPL in Emacs

38. Add web based REPL
~/.lein/profiles.clj
REPL: read, evaluate, print, loop – dynamic environment for Clojure
and other lisps

39. Leiningen WebRepl plugin

40. Local Repositories
(just like Maven)

41. Libraries kept in local .m2 folder

42. Repositories
https://github.com/technomancy/leiningen/blob/
preview/sample.project.clj

43. Running your
project

44. Create a new project
lein run
Runs the main function, or specify main with -m
option

45. Long running processes
lein trampoline run
-m my-app.server 5000
Web applications
- noir
- enclojure
- ring

46. Running Tests
lein tests
lein tests my.proj.code
lein help tests
Automating test runs ?

47. Deployment

48. Jars & Uber Jars
lein jar
- package up your project,
requires Clojure on the server
lein uberjar
- package up everything, even
Clojure

49. project.clj for jar / uberjar

50. Clojure code for jar / uberjar

51. Deploy to Clojars
Create a maven pom
lein pom
Create a maven pom
scp pom.xml myproject-0.1.0.jar
clojars@clojars.org:

52. Deploy to Clojars
Or just use lein-clojars
https://github.com/ato/lein-clojars

53. Deploying to the
Cloud

54. Uses your Leiningen project.clj
- Create your account & install the toolbelt
- Create your instance
- Push your git repo
- Fire up your browser
blog.raynes.me/blog/2011/11/03/moving-try-clojure-
to-heroku/
devcenter.heroku.com/articles/clojure-web-
application

55. Leiningen Plug-ins

56. Running scripts
Copying files
DVCS (git)
Continuous
Integration server
(Jenkins)

58. Leiningen.org
- Tutorials
- Github Repository
- News
- Bug reporting

59. Choose Life...
… choose Clojure

60. Thank you
@jr0cket
ClojureMadeSimple.co.uk
slideshare.net/jr0cket