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

10 KiB

Scala layer

/TakeV/spacemacs/media/commit/87cd00eac74f23dba6a2f1b816a50c44234b41a4/layers/+lang/scala/img/scala.png with /TakeV/spacemacs/media/commit/87cd00eac74f23dba6a2f1b816a50c44234b41a4/layers/+lang/scala/img/ensime.png

Description

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

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.

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

Usage

  1. Create a .ensime file at the root of your Scala project using sbt ensimeConfig and sbt ensimeConfigProject at the shell.
  2. 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.

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.

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-print-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

Ensime key bindings

Search

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

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

Typecheck

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

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 i step
SPC m d n next
SPC m d o step out
SPC m d q quit
SPC m d r run
SPC m d t backtrace
SPC m d v inspect value at point

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

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

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

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

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

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

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

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)

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