spacemacs/layers/+lang/elm

Elm layer

• Description
  • Features:
• Install
  • Layer
  • Elm Platform
    • macOS and Windows installers
    • Universal installer using npm
    • Source code
  • elm-oracle
  • elm-format
• Basic usage tips
  • Compilation
  • Reactor
  • On save usage
    • Imports sort
    • File format
  • Indentation
  • Test runner settings
• Key bindings
  • elm-make
  • elm-repl
  • elm-reactor
  • elm-test-runner
  • elm-package
    • package list buffer
  • elm-oracle
  • elm-format
  • Refactoring

Description

This layer adds support for Elm.

It relies on elm-mode and flycheck-elm.

Features:

• Syntax highlighting.
• Intelligent indentation
• Auto-completion integration for company (default) or auto-complete modes, with using elm-oracle
• Syntax checking support using flycheck
• Integration with elm-make
• Integration with elm-repl
• Integration with elm-reactor
• Integration with elm-package

Install

Layer

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

Elm Platform

The elm-platform is a bundle of tools, including the elm-compiler, elm-make, elm-reactor, elm-repl and elm-package.

Depending on the method of installation, the elm-mode package would need to be able to access commands such as elm-reactor or elm-make.

macOS and Windows installers

Official installers for these operating systems are available from: https://guide.elm-lang.org/install.html

Universal installer using npm

A npm based installer is available to, and provides pre-compiled binaries for certain operating system and architectures.

  npm install --global elm

Also, note that you might need to set the ELM_HOME environment variables to the corresponding directory created by the installer.

If you are facing problems with previewing a buffer with elm-reactor ensure that the absolute path of the npm global bin file is on your path within emacs

MacOS users facing problems with elm-reactor failing to properly install or run, see this issue https://github.com/kevva/elm-bin/issues/28.

Source code

To build from source, see instructions here: https://github.com/elm-lang/elm-platform

elm-oracle

elm-oracle can be used to show type signatures and docs for tokens under the cursor and provide support for auto-completion, but it is not part of the standard elm-platform.

Both the "company" and "auto-complete" backends are supported, but this layer is configured with company.

To install elm-oracle, install node.js and npm, then run this command:

  npm install -g elm-oracle

elm-format

elm-format can be used to format elm code according to a standard set of rules.

To install elm-format follow the instructions for the version of elm installed: https://github.com/avh4/elm-format

Also, note that if you use homebrew to install elm-format the installed exe has a version suffix, the installed command name can be set in your ~/spacemacs:

  (elm :variables
       elm-format-command "elm-format-0.17")

Basic usage tips

Compilation

To control the name of the compiled JavaScript file, use SPC m c B instead of SPC m c b. This will overwrite the --output parameter of elm-make to [buffer-name].js instead of the default.

Reactor

elm-reactor is an interactive development tool, used to develop and debug Elm programs. It will automatically compile an Elm program, and run it in the browser, with editor agnostic support for hot-swapping and time-travel debugging.

To preview Main.elm, press C-c C-m (or SPC m R m). Alternatively, to preview from buffer, press C-u C-c C-n (or SPC m R n). To preview in debug mode, prefix with C-u (or SPC u).

By default, elm-reactor with launch with its own generated index.html. To use a custom html, you'd need to load the debuger excplictly and use an http daemon to serve your custom file.

If needed, default values for host and port used by for the elm-reactor server can be controlled by passing in these variables in your ~/.spacemacs:

  (elm :variables
       elm-reactor-port "3000"          ; default 8000
       elm-reactor-address "0.0.0.0") ; default 127.0.0.1

On save usage

Imports sort

Set elm-sort-imports-on-save to t to sort the imports in the current file on every save.

  (elm :variables elm-sort-imports-on-save t)

File format

Set elm-format-on-save to t to format current file on every save.

  (elm :variables elm-format-on-save t)

Indentation

elm-mode indentation is based on cycling: every time you insert a new line there will be one or more indentation levels available for you to choose from. The exact number is printed in the minibuffer either as Sole indentation or Indent cycle (n)… where n is the number of available indentations to choose from. If the automatic indentation level was not the one you expected simply hit TAB to cycle through the list (note that hitting any other key will cancel the cycle).

Test runner settings

You may want to customize the default suffix for test files. For example, if you prefer to put your tests in HelloSpec.elm instead of HelloTest.elm, set the following variable:

  (elm :variables
       elm-test-runner-preferred-test-suffix "Spec")

Take a look here for more settings, and remember that this can be set by project using a dir-locals.el file.

Key bindings

elm-make

Key binding	Description
SPC m c b	elm-compile-buffer
SPC m c B	spacemacs/elm-compile-buffer-override-output
SPC m c m	elm-compile-main

elm-repl

Key binding	Description
SPC m s i	elm-repl-load
SPC m s f	send current function to REPL
SPC m s F	send current function to REPL and focus it in insert state
SPC m s r	send current region to REPL
SPC m s R	send current region to REPL and focus it in insert state

elm-reactor

Key binding	Description
SPC m R n	elm-preview-buffer
SPC m R m	elm-preview-main

elm-test-runner

Key binding	Description
SPC m t b	elm-test-runner-run
SPC m t d	elm-test-runner-run-directory
SPC m t p	elm-test-runner-run-project
SPC m t r	elm-test-runner-rerun
SPC m t w	elm-test-runner-watch
SPC m t TAB	elm-test-runner-toggle-test-and-target

elm-package

Key binding	Description
SPC m p i	elm-import
SPC m p c	elm-package-catalog
SPC m p d	elm-documentation-lookup

package list buffer

Key binding	Description
g	elm-package-refresh
v	elm-package-view
m	elm-package-mark
u	elm-package-unmark
x	elm-package-install
q	quit-window

elm-oracle

Key binding	Description
SPC m h h	elm-oracle-doc-at-point
SPC m h t	elm-oracle-type-at-point

elm-format

Key binding	Description
SPC m = b	elm-mode-format-buffer

Refactoring

Key binding	Description
SPC m r i	elm-sort-imports