Using Emacs with Ensime for Scala development

emacs_ensime_scala.md

This tutorial is tested on Debian linux. Should work on other platforms with minimal changes. This post really helped: http://jawher.net/2011/01/17/scala-development-environment-emacs-sbt-ensime/

• Install jdk and sbt (more on that: https://class.coursera.org/progfun-2012-001/wiki/view?page=ToolsSetup)

• Install scala-mode for Emacs:

  apt-get install subversion  # in case you don't have subversion already installed 
  svn export http://lampsvn.epfl.ch/svn-repos/scala/scala-tool-support/trunk/src/emacs scala-emacs
  mkdir ~/.emacs.d/scala  # creating folder for scala extensions
  mv scala-emacs ~/.emacs.d/scala  # moving scala-mode to new folder

• Update your ~/.emacs file:

  ; -== scala-mode ==-
  (add-to-list 'load-path "~/.emacs.d/scala/scala-emacs")
  (require 'scala-mode-auto) 
  
  (add-hook 'scala-mode-hook
           '(lambda ()
         (scala-mode-feature-electric-mode)
            ))

• Download last version of Ensime: https://github.com/aemoncannon/ensime/downloads It's an Emacs extension with awesome set of features for scala development.

• Unarchive Ensime and move it to our scala folder:

  tar xvfz ensime_2.9.2-0.9.8.1.tar.gz  # your file may have other name
  mv ensime_2.9.2-0.9.8.1 ~/.emacs.d/scala/ensime

• Update your ~/.emacs file to hook up Ensime:

  ; -== Ensime ==-
  (require 'scala-mode)
  (add-to-list 'auto-mode-alist '("\\.scala$" . scala-mode))
  (add-to-list 'load-path "~/.emacs.d/scala/ensime/elisp/")
  (require 'ensime)
  (add-hook 'scala-mode-hook 'ensime-scala-mode-hook)

• Create sbt plugins directory (if not present):Install ensime plugin for sbt:

  mkdir ~/.sbt/plugins

• Add ensime plugin for sbt:

  echo 'addSbtPlugin("org.ensime" % "ensime-sbt-cmd" % "0.1.0")' >> ~/.sbt/plugins/plugins.sbt

Creating simple sbt project

• Create and enter project directory

  mkdir ~/scala-hw
  sd ~/scala-hw

• Create and edit build.sbt. Don't delete empty lines. More on build.sbt: https://github.com/harrah/xsbt/wiki/Getting-Started-Basic-Def

  name := "hello_scala"
  
  version := "1.0"
  
  scalaVersion := "2.9.1"
  

• Create directory structure for project

  mkdir -p src/{main,test}/scala

• Create file src/main/scala/Main.scala and edit it with Emacs

  emacs src/main/scala/Main.scala

• Run sbt console and enter command 'ensime generate'

  sbt
  ensime generate
  

• Run emacs command ensime-config-gen to configure ensime for this project. Set ~/scala-hw as project root (when asked). Say 'yes' to question if project-type is 'sbt'.

  M-x ensime-config-gen
  ~/scala-hw
  yes
  

• Connect your project to ensime. Accept .ensime file proposition

  M-x ensime
  yes
  

• Write and save example program

  object HelloScala {
      def main(args: Array[String]) = println("Hello, Scala!")
  }

• Open sbt console:

  C-c C-b s
  

• Run project, by typing 'run' in sbt console.
• Learn how to use Emacs with ensime http://aemoncannon.github.com/ensime/index.html#tth_sEc4