141 lines
5.1 KiB
Org Mode
141 lines
5.1 KiB
Org Mode
#+TITLE: Scala layer
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#+TAGS: general|layer|multi-paradigm|programming
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[[file:img/scala.png]] with [[file:img/scalameta.png]]
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* Table of Contents :TOC_5_gh:noexport:
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- [[#description][Description]]
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- [[#features][Features:]]
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- [[#layer-installation][Layer Installation]]
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- [[#backends][Backends]]
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- [[#metals][Metals]]
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- [[#scalastyle][Scalastyle]]
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- [[#use-java-doc-style][Use Java doc-style]]
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- [[#enable-debug-adapter-protocol-dap][Enable Debug Adapter Protocol (DAP)]]
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- [[#automatically-insert-asterisk-in-multiline-comments][Automatically insert asterisk in multiline comments]]
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- [[#enable-gtags-as-a-fallback-navigation-utility][Enable GTags as a fallback navigation utility]]
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- [[#key-bindings][Key bindings]]
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- [[#sbt][sbt]]
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* Description
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This layer adds support for the Scala language to Spacemacs.
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** Features:
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- Syntax highlighting
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- Support for language backend using LSP and [[https://scalameta.org/metals/][Metals]]
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- Debugging support via =dap=
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- Auto-completion
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- Treeview support for viewing project structure and triggering compilation
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- Syntax-checking
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- Refactoring
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- Incremental compilation
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- Style linting
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- Optional GGTags search
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* Layer Installation
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To use this configuration layer, add it to your =~/.spacemacs=. You will need to
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add =scala= to the existing =dotspacemacs-configuration-layers= list in this
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file.
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+ To turn on the Metals tree view side bar, set =scala-auto-treeview= to =t=.
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+ To display SBT in a small buffer at the bottom of the frame, set the =scala-sbt-window-position= layer variable to =bottom=.
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* Backends
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The only currently supported language backend is =scala-metals=. Support for
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Ensime has been dropped as that project has been dead for some time.
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** Metals
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Currently, you must manually install the Metals server. It is possible to do so
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via coursier; the latest version can be built using the following commands,
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where =0.9.8= can be replaced with the current version of [[https://scalameta.org/metals/docs/editors/emacs.html][Metals]]:
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#+BEGIN_SRC bash
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./coursier bootstrap \
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--java-opt -Xss4m \
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--java-opt -Xms100m \
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--java-opt -Dmetals.client=emacs \
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org.scalameta:metals_2.12:0.9.8 \
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-r bintray:scalacenter/releases \
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-r sonatype:snapshots \
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-o /usr/local/bin/metals-emacs -f
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#+END_SRC
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Notice that the layer by default overwrites Metals-scala tree view to nil.
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This to avoid issues with buffers when rendering VSCode like view, issue described [[https://github.com/syl20bnr/spacemacs/pull/14470][Here]].
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You will then have the common LSP key bindings; see
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[[https://github.com/syl20bnr/spacemacs/tree/develop/layers/%2Btools/lsp#key-bindings][LSP#key-bindings]] for more details.
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* Scalastyle
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[[http://www.scalastyle.org/][Scalastyle]] provides style-checking and linting. The Emacs functionality is
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provided by Flycheck.
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To use scalastyle, it must be present as an executable in your =PATH=.
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- macOS users: =brew install scalastyle=
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- Linux, please see [[http://www.scalastyle.org/command-line.html]]
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To test if =scalastyle= executable is in your path, run =scalastyle= in a new
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terminal, it should output something like:
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#+BEGIN_SRC bash
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$ scalastyle
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scalastyle 0.8.0
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Usage: scalastyle [options] <source directory>
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...
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#+END_SRC
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Finally, enable the =syntax-checking= layer and set the =flycheck-scalastylerc=
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variable to a valid location.
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#+BEGIN_SRC emacs-lisp
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(setq-default flycheck-scalastylerc "/usr/local/etc/scalastyle_config.xml")
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#+END_SRC
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See the [[http://www.flycheck.org/en/latest/languages.html?highlight=scala#syntax-checker-scala-scalastyle][flycheck documentation]] and [[http://www.scalastyle.org/configuration.html][scalastyle configuration]] for up-to-date
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configuration instructions.
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** Use Java doc-style
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To enable =java-doc-style=, set the variable =scala-indent:use-javadoc-style= to
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=t=
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#+BEGIN_SRC emacs-lisp
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(setq-default dotspacemacs-configuration-layers '(
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(scala :variables scala-indent:use-javadoc-style t)))
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#+END_SRC
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* Enable Debug Adapter Protocol (DAP)
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The metals backend enables integration with the DAP layer for debugging support.
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* Automatically insert asterisk in multiline comments
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To insert a leading asterisk in multiline comments automatically, set the
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variable =scala-auto-insert-asterisk-in-comments= to =t=.
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#+BEGIN_SRC emacs-lisp
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(setq-default dotspacemacs-configuration-layers '(
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(scala :variables scala-auto-insert-asterisk-in-comments t)))
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#+END_SRC
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* Enable GTags as a fallback navigation utility
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To enable gtags when in =scala-mode= set the variable =scala-enable-gtags= to =t=.
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#+BEGIN_SRC emacs-lisp
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(setq-default dotspacemacs-configuration-layers '(
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(scala :variables scala-enable-gtags t)))
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#+END_SRC
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* Key bindings
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Additional major mode key bindings are populated by LSP and DAP.
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** sbt
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| Key binding | Description |
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|-------------+-----------------------------|
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| ~SPC m b .~ | SBT transient state |
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| ~SPC m b b~ | SBT command |
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| ~SPC m b c~ | Run ~compile~ in SBT |
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| ~SPC m b t~ | Run ~test~ in SBT |
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| ~SPC m b I~ | Run ~It / compile~ in SBT |
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| ~SPC m b T~ | Run ~Test / compile~ in SBT |
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| ~SPC m b =~ | Run ~scalafmtAll~ in SBT |
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