Scala layer

Table of ContentsClose

1. Description
2. Layer Installation
3. Ensime
- 3.1. Installation
- 3.2. Usage
4. Scalastyle
- 4.1. Use Java doc-style
5. Automatically show the type of the symbol under the cursor
6. Automatically insert asterisk in multiline comments
7. Automatically replace arrows with unicode ones
8. Auto-start
9. Key bindings
- 9.1. Ensime key bindings

with

1 Description

This layer adds support for the Scala language using the excellent ENSIME client/server.

2 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.

3 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 to generate these files.

3.1 Installation

Refer to the Ensime installation instructions to install the sbt-ensime plugin.

Please note you have to use a version newer than 0.13.5 of sbt in your project's project/build.properties. For example,

sbt.version=0.13.11

3.2 Usage

Create a .ensime file at the root of your Scala project using sbt ensimeConfig and sbt ensimeConfigProject at the shell.
Run M-x ensime within Emacs to start an ENSIME session.

Each Scala project uses a dedicated ENSIME session, so you only need to run M-x ensime once per project. Any Scala files you create or visit within the project will automatically use ENSIME for the remainder of your editing session.

4 Scalastyle

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

To use scalastyle,

Download the scalastyle jar and put it somewhere sensible
- If you are a brew user in OSX you can do: brew install scalastyle
Customise the flycheck-scalastyle-jar and flycheck-scalastylerc variables in your dotspacemacs/user-config i.e.:

(setq flycheck-scalastyle-jar
      "/usr/local/Cellar/scalastyle/0.8.0/libexec/scalastyle_2.11-0.8.0-batch.jar")
(setq flycheck-scalastylerc
      "/usr/local/etc/scalastyle_config.xml")

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

4.1 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)))

5 Automatically show the type of the symbol under the cursor

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

(setq-default dotspacemacs-configuration-layers '(
  (scala :variables scala-use-java-doc-style t)))

Enabling this option can cause slow editor performance.

6 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)))

7 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)))

8 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)))

9 Key bindings

9.1 Ensime key bindings

9.1.1 Search

Key Binding	Description
`SPC m /`	incremental search using `ensime-scalex` major mode
`SPC m ?`	incremental search in all live buffers

9.1.2 sbt

Key Binding	Description
`SPC m b .`	sbt transient state
`SPC m b b`	sbt command
`SPC m b c`	compile
`SPC m b C`	clean command
`SPC m b i`	switch to sbt shell
`SPC m b p`	package command
`SPC m b r`	run command

9.1.3 Typecheck

Key Binding	Description
`SPC m c t`	type check the current file
`SPC m c T`	type check all the open buffers

9.1.4 Debug

Key Binding	Description
`SPC m d A`	Attach to a remote debugger
`SPC m d b`	set breakpoint
`SPC m d B`	clear breakpoint
`SPC m d C`	clear all breakpoints
`SPC m d c`	continue
`SPC m d d`	start a debug session
`SPC m d i`	inspect value at point
`SPC m d l`	list local variables
`SPC m d n`	next
`SPC m d o`	step out
`SPC m d q`	quit
`SPC m d r`	run
`SPC m d s`	step
`SPC m d t`	backtrace

Note: These key bindings need a transient-state, PR welcome :-)

9.1.5 Errors

Key Binding	Description
`SPC m e e`	print error at point
`SPC m e l`	show all errors and warnings
`SPC m e s`	switch to buffer containing the stack trace parser

9.1.6 Goto

Key Binding	Description
`SPC m g g`	go to definition
`SPC m g i`	go to implementation
`SPC m g t`	go to test

9.1.7 Print and yank types

`SPC m h T`	print full type name at point
`SPC m h t`	print short type name at point
`SPC m y T`	yank full type name at point
`SPC m y t`	yank short type name at point

9.1.8 Documentation, Inspect

Key Binding	Description
`SPC m h h`	show documentation for symbol at point
`SPC m h u`	show uses for symbol at point
`SPC m i i`	inspect type at point
`SPC m i I`	inspect type in other frame
`SPC m i p`	inspect project package

9.1.9 Server

Key Binding	Description
`SPC m n F`	reload open files
`SPC m n s`	start ensime server
`SPC m n S`	regenerate the `.ensime` and restart the ensime server

9.1.10 Refactoring

Key Binding	Description
`SPC m r a`	add type annotation
`SPC m r f`	format source
`SPC m r d`	get rid of an intermediate variable (`ensime-refactor-inline-local`)
`SPC m r D`	get rid of an intermediate variable (`ensime-undo-peek`)
`SPC m r i`	organize imports
`SPC m r m`	extract a range of code into a method
`SPC m r r`	rename a symbol project wide
`SPC m r t`	import type at point
`SPC m r v`	extract a range of code into a variable
`SPC m z`	expand/contract region

9.1.11 Tests

Key Binding	Description
`SPC m t a`	test command (sbt)
`SPC m t r`	test quick command (sbt)
`SPC m t t`	test only (sbt)

9.1.12 REPL

Key Binding	Description
`SPC m s a`	ask for a file to be loaded in the REPL
`SPC m s b`	send buffer to the REPL
`SPC m s B`	send buffer to the REPL and focus the REPL buffer in `insert state`
`SPC m s i`	start or switch to the REPL inferior process
`SPC m s r`	send region to the REPL
`SPC m s R`	send region to the REPL and focus the REPL buffer in `insert state`