spacemacs/layers/+lang/scala/README.org

Scala layer

• Description
  • Features:
• Layer Installation
• Ensime
• Scalastyle
  • Use Java doc-style
• Automatically show the type of the symbol under the cursor
• Automatically insert asterisk in multiline comments
• Automatically replace arrows with unicode ones
• Auto-start
• Key bindings

with

Description

This layer adds support for the Scala language to Spacemacs.

Features:

• Syntax highlighting
• Auto-completion
• Syntax-checking
• Refactoring
• Incremental compilation
• Scala Repl
• Style linting
• Eldoc integration
• Test execution directly from Emacs
• Automatic replacement of ASCII arrows with unicode ones
• Automatic starting/stopping of ENSIME IDE server

Layer Installation

To use this configuration layer, add it to your ~/.spacemacs. You will need to add scala to the existing dotspacemacs-configuration-layers list in this file.

Then, you should modify your ~/.spacemacs to use the recommended Ensime version (Stable). Please add the following lines to dotspacemacs/user-init:

  (add-to-list 'configuration-layer-elpa-archives '("melpa-stable" . "stable.melpa.org/packages/"))
  (add-to-list 'package-pinned-packages '(ensime . "melpa-stable"))

Ensime

ENSIME provides IDE-like features, such as refactoring, incremental compilation and project-wide type-checking.

ENSIME requires a configuration file at the root of each Scala project. It provides an SBT plugin, a gradle plugin and others (see ensime.org for a full list) to generate these files.

Installation instructions and usage can be found in the Java layer README.org.

Scalastyle

Scalastyle provides style-checking and linting. The Emacs functionality is provided by Flycheck.

To use scalastyle, it must be present as an executable in your PATH.

• OSX users: brew install scalastyle
• Linux, please see http://www.scalastyle.org/command-line.html

To test if scalastyle executable is in your path, run scalastyle in a new terminal, it should output something like:

  $ scalastyle
  scalastyle 0.8.0
  Usage: scalastyle [options] <source directory>
  ...

Finally, enable the syntax-checking layer and set the flycheck-scalastylerc variable to a valid location.

  (setq-default flycheck-scalastylerc "/usr/local/etc/scalastyle_config.xml")

See the flycheck documentation and scalastyle configuration for up-to-date configuration instructions.

Use Java doc-style

To enable java-doc-style, set the variable scala-indent:use-javadoc-style to t

  (setq-default dotspacemacs-configuration-layers '(
    (scala :variables scala-indent:use-javadoc-style t)))

Automatically show the type of the symbol under the cursor

To enable the feature ensime-type-at-point when cursor moves, set the variable scala-enable-eldoc to t.

  (setq-default dotspacemacs-configuration-layers '(
    (scala :variables scala-enable-eldoc t)))

Enabling this option can cause slow editor performance.

Automatically insert asterisk in multiline comments

To insert a leading asterisk in multiline comments automatically, set the variable scala-auto-insert-asterisk-in-comments to t.

  (setq-default dotspacemacs-configuration-layers '(
    (scala :variables scala-auto-insert-asterisk-in-comments t)))

Automatically replace arrows with unicode ones

To replace =>, -> and <- with unicode arrows ⇒, → and ←, set the variable scala-use-unicode-arrows to t.

If in some occasions you don't want the arrows replaced (for example when defining compound operators like =>>), you can always undo the change and get the ascii arrows back.

  (setq-default dotspacemacs-configuration-layers '(
    (scala :variables scala-use-unicode-arrows t)))

Auto-start

If you prefer to have Ensime start when you load a scala file, you can enable it with

  (setq-default dotspacemacs-configuration-layers '(
      (scala :variables scala-auto-start-ensime t)))

Key bindings

All ensime key bindings are listed in the java layer README.org.