path: root/doc/ale.txt

*ale.txt*  For Vim version 8.0.
*ale*

ALE - Asynchronous Lint Engine

===============================================================================
CONTENTS                                                         *ale-contents*

  1. Introduction.........................|ale-introduction|
  2. Supported Languages & Tools..........|ale-support|
  3. Global Options.......................|ale-options|
  4. Linter Options and Recommendations...|ale-linter-options|
    asm...................................|ale-asm-options|
      gcc.................................|ale-asm-gcc|
    c.....................................|ale-c-options|
      clang...............................|ale-c-clang|
      cppcheck............................|ale-c-cppcheck|
      gcc.................................|ale-c-gcc|
    cpp...................................|ale-cpp-options|
      clang...............................|ale-cpp-clang|
      clangtidy...........................|ale-cpp-clangtidy|
      cppcheck............................|ale-cpp-cppcheck|
      gcc.................................|ale-cpp-gcc|
    css...................................|ale-css-options|
      stylelint...........................|ale-css-stylelint|
    cmake.................................|ale-cmake-options|
      cmakelint...........................|ale-cmake-cmakelint|
    erlang................................|ale-erlang-options|
      erlc................................|ale-erlang-erlc|
    fortran...............................|ale-fortran-options|
      gcc.................................|ale-fortran-gcc|
    html..................................|ale-html-options|
      htmlhint............................|ale-html-htmlhint|
      tidy................................|ale-html-tidy|
    java..................................|ale-java-options|
      javac...............................|ale-java-javac|
    javascript............................|ale-javascript-options|
      eslint..............................|ale-javascript-eslint|
      flow................................|ale-javascript-flow|
      jshint..............................|ale-javascript-jshint|
      xo..................................|ale-javascript-xo|
    lua...................................|ale-lua-options|
      luacheck............................|ale-lua-luacheck|
    ocaml.................................|ale-ocaml-options|
      merlin..............................|ale-ocaml-merlin|
    perl..................................|ale-perl-options|
      perl................................|ale-perl-perl|
    php...................................|ale-php-options|
      phpcs...............................|ale-php-phpcs|
      phpmd...............................|ale-php-phpmd|
    python................................|ale-python-options|
      flake8..............................|ale-python-flake8|
      mypy................................|ale-python-mypy|
      pylint..............................|ale-python-pylint|
    ruby..................................|ale-ruby-options|
      rubocop.............................|ale-ruby-rubocop|
    rust..................................|ale-rust-options|
      cargo...............................|ale-rust-cargo|
      rustc...............................|ale-rust-rustc|
    sass..................................|ale-sass-options|
      stylelint...........................|ale-sass-stylelint|
    scss..................................|ale-scss-options|
      stylelint...........................|ale-scss-stylelint|
    sh....................................|ale-sh-options|
      shell...............................|ale-sh-shell|
      shellcheck..........................|ale-sh-shellcheck|
    tex...................................|ale-tex-options|
      chktex..............................|ale-tex-chktex|
      lacheck.............................|ale-tex-lacheck|
    vim...................................|ale-vim-options|
      vint................................|ale-vim-vint|
    yaml..................................|ale-yaml-options|
      yamllint............................|ale-yaml-yamllint|
  5. Commands/Keybinds....................|ale-commands|
  6. API..................................|ale-api|
  7. Special Thanks.......................|ale-special-thanks|
  8. Contact..............................|ale-contact|

===============================================================================
1. Introduction                                              *ale-introduction*

ALE provides the means to run linters asynchronously in Vim in a variety of
languages and tools. ALE sends the contents of buffers to linter programs
using the |job-control| features available in Vim 8 and NeoVim. For Vim 8,
Vim must be compiled with the |job| and |channel| and |timer| features
as a minimum.

ALE supports the following key features:

1. Running linters when text is changed.
2. Running linters when files are opened.
3. Running linters when files are saved. (When a global flag is set.)
4. Populating the |loclist| with warning and errors.
5. Setting |signs| with warnings and errors for error markers.
6. Using |echo| to show error messages when the cursor moves.

===============================================================================
2. Supported Languages & Tools                                    *ale-support*

The following languages and tools are supported.

* ASM: 'gcc'
* Ansible: 'ansible-lint'
* Asciidoc: 'proselint'
* Bash: 'shell' (-n flag), 'shellcheck'
* Bourne Shell: 'shell' (-n flag), 'shellcheck'
* C: 'cppcheck', 'gcc', 'clang'
* C++ (filetype cpp): 'clang', 'clangtidy', 'cppcheck', 'gcc'
* C#: 'mcs'
* Chef: 'foodcritic'
* CMake: 'cmakelint'
* CoffeeScript: 'coffee', 'coffelint'
* CSS: 'csslint', 'stylelint'
* Cython (pyrex filetype): 'cython'
* D: 'dmd'
* Dockerfile: 'hadolint'
* Elixir: 'credo', 'dogma'
* Elm: 'elm-make'
* Erlang: 'erlc'
* Fortran: 'gcc'
* Go: 'gofmt -e', 'go vet', 'golint', 'go build'
* Haml: 'hamllint'
* Haskell: 'ghc', 'hlint'
* HTML: 'HTMLHint', 'proselint', 'tidy'
* Java: 'javac'
* JavaScript: 'eslint', 'jscs', 'jshint', 'flow', 'xo'
* JSON: 'jsonlint'
* LaTeX: 'chktex', 'lacheck'
* Lua: 'luacheck'
* Markdown: 'mdl', 'proselint'
* MATLAB: 'mlint'
* nim: 'nim check'
* nix: 'nix-instantiate'
* nroff: 'proselint'
* OCaml: 'merlin' (see |ale-linter-integration-ocaml-merlin|)
* Perl: 'perl' (-c flag), 'perlcritic'
* PHP: 'hack', 'php' (-l flag), 'phpcs', 'phpmd'
* Pod: 'proselint'
* Pug: 'pug-lint'
* Puppet: 'puppet', 'puppet-lint'
* Python: 'flake8', 'mypy', 'pylint'
* reStructuredText: 'proselint'
* Rust: 'rustc' (see |ale-integration-rust|)
* Ruby: 'rubocop'
* SASS: 'sasslint', 'stylelint'
* SCSS: 'sasslint', 'scsslint', 'stylelint'
* Scala: 'scalac'
* Slim: 'slim-lint'
* SML: 'smlnj'
* Swift: 'swiftlint'
* Tex: 'proselint'
* Texinfo: 'proselint'
* Text: 'proselint'
* TypeScript: 'tslint', 'typecheck'
* Verilog: 'iverilog', 'verilator'
* Vim: 'vint'
* Vim help: 'proselint'
* XHTML: 'proselint'
* YAML: 'yamllint'

===============================================================================
3. Global Options                                                 *ale-options*

g:airline#extensions#ale#enabled             *g:airline#extensions#ale#enabled*

  Type: |Number|
  Default: `1`

  Enables or disables the |airline|'s native extension for ale, which displays
  warnings and errors in the status line, prefixed by
  |airline#extensions#ale#error_symbol| and
  |airline#extensions#ale#warning_symbol|.


g:ale_echo_cursor                                           *g:ale_echo_cursor*

  Type: |Number|
  Default: `1`

  When this option is set to `1`, a truncated message will be echoed when a
  cursor is near a warning or error. ALE will attempt to find the warning or
  error at a column nearest to the cursor when the cursor is resting on a line
  which contains a warning or error. This option can be set to `0` to disable
  this behaviour.
  The format of the message can be customizable in |g:ale_echo_msg_format|.


g:ale_echo_msg_error_str                             *g:ale_echo_msg_error_str*

  Type: |String|
  Default: `Error`

  The string used for error severity in the echoed message.
  Note |`g:ale_echo_cursor`| should be set to 1
  Note |`g:ale_echo_msg_format`| should contain the `%severity%` handler


g:ale_echo_msg_format                                   *g:ale_echo_msg_format*

  Type: |String|
  Default: `%s`

  This variable defines the format of the echoed message. The `%s` is the
  error message itself, and it can contain the following handlers:
  - `%linter%` for linter's name
  - `%severity%` for the type of severity
  Note |`g:ale_echo_cursor`| should be setted to 1


g:ale_echo_msg_warning_str                         *g:ale_echo_msg_warning_str*

  Type: |String|
  Default: `Warning`

  The string used for warning severity in the echoed message.
  Note |`g:ale_echo_cursor`| should be set to 1
  Note |`g:ale_echo_msg_format`| should contain the `%severity%` handler


g:ale_emit_conflict_warnings                     *g:ale_emit_conflict_warnings*

  Type: |Number|
  Default: `1`

  When set to `0`, ALE will not emit any warnings on startup about conflicting
  plugins. ALE will probably not work if other linting plugins are installed.


g:ale_enabled                                                   *g:ale_enabled*

  Type: |Number|
  Default: `1`

  When set to `0`, this option will completely disable ALE, such that no
  error checking will be performed, etc. ALE can be toggled on and off with
  the |ALEToggle| command, which changes this option.


g:ale_history_enabled                                   *g:ale_history_enabled*

  Type: |Number|
  Default: `1`

  When set to `1`, ALE will remember the last few commands which were run
  for every buffer which is open. This information can be viewed with the
  |ALEInfo| command. The size of the buffer can be controlled with the
  |g:ale_max_buffer_history_size| option.

  This option can be disabled if storing a command history is not desired.


g:ale_history_log_output                             *g:ale_history_log_output*

  Type: |Number|
  Default: `0`

  When set to `1`, ALE will store the output of commands which have completed
  successfully in the command history, and the output will be displayed when
  using |ALEInfo|.

  |g:ale_history_enabled| must be set to `1` for this output to be stored or
  printed.

  ALE will likely consume a lot of memory if this option is on, so it should
  only be used for debugging problems with linters.


g:ale_keep_list_window_open                       *g:ale_keep_list_window_open*

  Type: |Number|
  Default: `0`

  When set to `1`, this option will keep the loclist or quickfix windows
  event after all warnings/errors have been removed for files. By default
  the loclist or quicfix windows will be closed automatically when there
  are no warnings or errors.

  See: |g:ale_open_list|


g:ale_lint_delay                                             *g:ale_lint_delay*

  Type: |Number|
  Default: `200`

  This variable controls the milliseconds delay after which the linters will
  be run after text is changed. This option is only meaningful with the
  |g:ale_lint_on_text_changed| variable set to `1`.


g:ale_lint_on_enter                                       *g:ale_lint_on_enter*

  Type: |Number|
  Default: `1`

  When this option is set to `1`, the |BufEnter| and |BufRead| events will be
  used to apply linters when buffers are first opened. If this is not desired,
  this variable can be set to `0` in your vimrc file to disable this
  behaviour.


g:ale_lint_on_filetype_changed                 *g:ale_lint_on_filetype_changed*

  Type: |Number|
  Default: `1`

  This option will cause ALE to run whenever the filetype is changed. A short
  delay will be used before linting will be done, so the filetype can be
  changed quickly several times in a row, but resulting in only one lint
  cycle.


g:ale_lint_on_save                                         *g:ale_lint_on_save*

  Type: |Number|
  Default: `1`

  This option will make ALE run the linters whenever a file is saved when it
  it set to `1` in your vimrc file. This option can be used in combination
  with the |g:ale_lint_on_enter| and |g:ale_lint_on_text_changed| options to
  make ALE only check files after that have been saved, if that is what is
  desired.


g:ale_lint_on_text_changed                         *g:ale_lint_on_text_changed*

  Type: |Number|
  Default: `1`

  By default, ALE will check files with the various supported programs when
  text is changed by using the |TextChanged| event. If this behaviour is not
  desired, then this option can be disabled by setting it to 0. The
  |g:ale_lint_delay| variable will be used to set a |timer_start()| on a
  delay, and each change to a file will continue to call |timer_stop()| and
  |timer_start()| repeatedly until the timer ticks by, and the linters will be
  run. The checking of files will run in the background, so it should not
  inhibit editing files.


g:ale_linter_aliases                                     *g:ale_linter_aliases*

  Type: |Dictionary|
  Default: `{}`

  The |g:ale_linter_aliases| option can be used to set aliases from one
  filetype to another. A given filetype can be mapped to use the linters
  run for another given filetype.

  This |Dictionary| will be merged with a default dictionary containing the
  following values: >

  {
  \   'zsh': 'sh',
  \   'csh': 'sh',
  \}
<
  For example, if you wish to map a new filetype `'foobar'` to run the `'php'`
  linters, you could set the following: >

  let g:ale_linter_aliases = {'foobar': 'php'}
<
  When combined with the |g:ale_linters| option, the original filetype
  (`'foobar'`) will be used for determining which linters to run,
  not the aliased type (`'php'`). This allows an aliased type to run a
  different set of linters from the type it is being mapped to.


g:ale_linters                                                   *g:ale_linters*

  Type: |Dictionary|
  Default: `{}`

  The |g:ale_linters| option sets a |Dictionary| mapping a filetype
  to a |List| of linter programs to be run when checking particular filetypes.
  Only the filetypes specified in the dictionary will be limited in terms
  of which linters will be run.

  This |Dictionary| will be merged with a default dictionary containing the
  following values: >

  {
  \   'csh': ['shell'],
  \   'rust': ['cargo'],
  \   'text': [],
  \   'zsh': ['shell'],
  \}
<
  This option can be used to enable only a particular set of linters for a
  file. For example, you can enable only 'eslint' for JavaScript files: >

  let g:ale_linters = {'javascript': ['eslint']}
<
  If you want to disable all linters for a particular filetype, you can pass
  an empty list of linters as the value: >

  let g:ale_linters = {'javascript': []}
<
  All linters available for a given filetype can be enabled by using the
  string `'all'`: >

  let g:ale_linters = {'c': 'all'}
<

g:ale_max_buffer_history_size                   *g:ale_max_buffer_history_size*

  Type: |Number|
  Default: `20`

  This setting controls the maximum number of commands which will be stored in
  the command history used for |ALEInfo|. Command history will be rotated in
  a FIFO manner. If set to a number <= 0, then the history will be
  continuously set to an empty |List|.

  History can be disabled completely with |g:ale_history_enabled|.


g:ale_open_list                                               *g:ale_open_list*

  Type: |Number|
  Default: `0`

  When set to `1`, this will cause ALE to automatically open a window for
  the loclist (|lopen|) or for the quickfix list instead if
  |g:ale_set_quickfix| is `1`. (|copen|)

  The window will be kept open until all warnings or errors are cleared,
  including those not set by ALE, unless |g:ale_keep_list_window_open| is set
  to `1`, in which case the window will be kept open until closed manually.


g:ale_set_highlights                                     *g:ale_set_highlights*

  Type: |Number|
  Default: `has('syntax')`

  When this option is set to `1`, highlights will be set in for erros and
  warnings. The `ALEError` and `ALEWarning` highlight groups will be used to
  provide highlights, and default to linking to `SpellBad` and `SpellCap`
  respectively by default.


g:ale_set_loclist                                           *g:ale_set_loclist*

  Type: |Number|
  Default: `1`

  When this option is set to `1`, the |loclist| will be populated with any
  warnings and errors which are found by ALE. This feature can be used to
  implement jumping between errors through typical use of |lnext| and |lprev|.


g:ale_set_quickfix                                         *g:ale_set_quickfix*

  Type: |Number|
  Default: `0`

  When this option is set to `1`, the |quickfix| list will be populated with any
  warnings and errors which are found by ALE, instead of the |loclist|. The
  loclist will never be populated when this option is on.


g:ale_set_signs                                               *g:ale_set_signs*

  Type: |Number|
  Default: `has('signs')`

  When this option is set to `1`, the |sign| column will be populated with
  signs marking where errors and warnings appear in the file. The
  `ALEErrorSign` and `ALEWarningSign` highlight groups will be used to provide
  highlighting for the signs. The text used for signs can be customised with
  the |g:ale_sign_error| and |g:ale_sign_warning| options.


g:ale_sign_column_always                             *g:ale_sign_column_always*

  Type: |Number|
  Default: `0`

  By default, the sign gutter will disappear when all warnings and errors have
  been fixed for a file. When this option is set to `1`, the sign column will
  remain open. This can be preferable if you don't want the text in your file
  to move around as you edit a file.


g:ale_sign_error                                             *g:ale_sign_error*

  Type: |String|
  Default: `'>>'`

  This string can be changed to change the characters used for the sign gutter
  for lines which at least one error on them. Lines with both errors and
  warnings on them will show the error marker, as errors take precedence.


g:ale_sign_offset                                           *g:ale_sign_offset*

  Type: |Number|
  Default: `1000000`

  This variable controls offset from which numeric IDs will be generated for
  new signs. Signs cannot share the same ID values, so when two Vim plugins
  set signs at the same time, the IDs have to be configured such that they do
  not conflict with one another. If the IDs used by ALE are found to conflict
  with some other plugin, this offset value can be changed, and hopefully both
  plugins will work together. See |sign-place| for more information on how
  signs are set.


g:ale_sign_warning                                         *g:ale_sign_warning*

  Type: |String|
  Default: `'--'`

  This string can be changed to change the characters used for the sign gutter
  for lines which at least one warning on them.


g:ale_statusline_format                               *g:ale_statusline_format*

  Type: |List|
  Default: `['%d error(s)', '%d warning(s)', 'OK']`

  This variable defines the format of |`ale#statusline#status()`| output.
  - The 1st element is for errors
  - The 2nd element is for warnings
  - The 3rd element is for when no errors are detected


g:ale_warn_about_trailing_whitespace     *g:ale_warn_about_trailing_whitespace*

  Type: |Number|
  Default: `1`

  When this option is set to `1`, warnings relating to trailing whitespace on
  lines will be shown in signs, the loclist, and echo messages, etc. If these
  errors are found to be too irritating while edits are being made, and you
  have configured Vim to automatically remove trailing whitespace, then you
  can disable these warnings for some linters by setting this option to `0`.

  Not all linters may respect this option. If a linter does not, please file a
  bug report, and it may be possible to add such support.


===============================================================================
4. Linter Options and Recommendations                      *ale-linter-options*

Linter options are documented in individual help files. See the table of
contents at |ale-contents|.


===============================================================================
5. Commands/Keybinds                                             *ale-commands*

ALELint                                                               *ALELint*

  Run ALE once for the current buffer. This command can be used to run ALE
  manually, instead of automatically, if desired.

  This command will also run linters where `lint_file` is set to `1`, or in
  other words linters which check the file instead of the Vim buffer.

  A plug mapping `<Plug>(ale_lint)` is defined for this command.


ALEPrevious                                                       *ALEPrevious*
ALEPreviousWrap                                               *ALEPreviousWrap*
ALENext                                                               *ALENext*
ALENextWrap                                                       *ALENextWrap*
                                                      *ale-navigation-commands*

  Move between warnings or errors in a buffer. ALE will only navigate between
  the errors or warnings it generated, even if both |g:ale_set_quickfix|
  and |g:ale_set_loclist| are set to `0`.

  `ALEPrevious` and `ALENext` will stop at the top and bottom of a file, while
  `ALEPreviousWrap` and `ALENextWrap` will wrap around the file to find
  the last or first warning or error in the file, respectively.

  The following |<Plug>| mappings are defined for the commands: >
  <Plug>(ale_previous) - ALEPrevious
  <Plug>(ale_previous_wrap) - ALEPreviousWrap
  <Plug>(ale_next) - ALENext
  <Plug>(ale_next_wrap) - ALENextWrap
<
  For example, these commands could be bound to the keys Ctrl + j
  and Ctrl + k: >

  " Map movement through errors without wrapping.
  nmap <silent> <C-k> <Plug>(ale_previous)
  nmap <silent> <C-j> <Plug>(ale_next)
  " OR map keys to use wrapping.
  nmap <silent> <C-k> <Plug>(ale_previous_wrap)
  nmap <silent> <C-j> <Plug>(ale_next_wrap)
<

ALEToggle                                                           *ALEToggle*
ALEEnable                                                           *ALEEnable*
ALEDisable                                                         *ALEDisable*

  Enable or disable ALE, including all of its autocmd events, loclist items,
  quickfix items, signs, current jobs, etc. Calling this option will change
  the |g:ale_enabled| variable.


ALEDetail                                                           *ALEDetail*

  Show the full linter message for the current line. This will only have an
  effect on lines that contain a linter message.

  A plug mapping `<Plug>(ale_detail)` is defined for this command.

===============================================================================
6. API                                                                *ale-api*

ale#Queue(delay, [linting_flag])                                  *ale#Queue()*

  Run linters for the current buffer, based on the filetype of the buffer,
  with a given `delay`. A `delay` of `0` will run the linters immediately.
  The linters will always be run in the background. Calling this function
  again from the same buffer

  An optional `linting_flag` argument can be given. If `linting_flag`
  is `'lint_file'`, then linters where the `lint_file` option is set to `1` will be
  run. Linters with `lint_file` set to `1` are not run by default.


ale#engine#EscapeCommandPart(command_part)     *ale#engine#EscapeCommandPart()*

  Given a |String|, return a |String| with all `%` characters replaced with
  `%%` instead. This function can be used to escape strings which are
  dynamically generated for commands before handing them over to ALE,
  so that ALE doesn't treat any strings with `%` formatting sequences
  specially.


ale#engine#GetLoclist(buffer)                         *ale#engine#GetLoclist()*

  Given a buffer number, this function will rerurn the list of warnings and
  errors reported by ALE for a given buffer in the format accepted by
  |setqflist()|.


ale#engine#ManageFile(buffer, filename)               *ale#engine#ManageFile()*

  Given a buffer number for a buffer currently running some linting tasks
  and a filename, register a filename with ALE for automatic deletion after
  linting is complete, or when Vim exits.

  If Vim exits suddenly, ALE will try its best to remove temporary files, but
  ALE cannot guarantee with absolute certainty that the files will be removed.
  It is advised to create temporary files in the operating system's managed
  temporary file directory, such as with |tempname()|.

  Directory names should not be given to this function. ALE will only delete
  files and symlinks given to this function. This is to prevent entire
  directories from being accidentally deleted, say in cases of writing
  `dir . '/' . filename` where `filename` is actually `''`, etc. ALE instead
  manages directories separetly with the |ale#engine#ManageDirectory| function.


ale#engine#ManageDirectory(buffer, directory)    *ale#engine#ManageDirectory()*

  Like |ale#engine#ManageFile()|, but directories and all of their contents
  will be deleted, akin to `rm -rf directory`, which could lead to loss of
  data if mistakes are made. This command will also delete any temporary
  filenames given to it.

  It is advised to use |ale#engine#ManageFile()| instead for deleting single
  files.


ale#linter#Define(filetype, linter)                       *ale#linter#Define()*

  Given a |String| for a filetype and a |Dictionary| Describing a linter
  configuration, add a linter for the given filetype. The dictionaries each
  offer the following options:

  `name`                   The name of the linter. These names will be used by
                         |g:ale_linters| option for enabling/disabling
                         particular linters.

                         This argument is required.

  `callback`               A |String| or |Funcref| for a callback function
                         accepting two arguments (buffer, lines), for a
                         buffer number the output is for, and the lines of
                         output from a linter.

                         This callback function should return a |List| of
                         |Dictionary| objects in the format accepted by
                         |setqflist()|. The |List| will be sorted by line and
                         then column order so it can be searched with a binary
                         search by in future before being passed on to the
                         |loclist|, etc.

                         This argument is required.

                         The keys for each item in the List will be handled in
                         the following manner:

                         `text` - This error message is required.
                         `lnum` - The line number is required. Any strings
                           will be automatically converted to numbers by
                           using `str2nr()`.

                           Line 0 will be moved to line 1, and lines beyond
                           the end of the file will be moved to the end.
                         `col` - The column number is optional and will
                           default to `0`. Any strings will be automatically
                           coverted to number using `str2nr()`.
                         `bufnr` - The buffer number should match the buffer
                           being checked, and this value will default to
                           the buffer being checked.
                         `vcol` - Defaults to `0`.
                         `type` - Defaults to `'E'`.
                         `nr` - Defaults to `-1`.

  `executable`             A |String| naming the executable itself which
                         will be run. This value will be used to check if the
                         program requested is installed or not.

                         Either this or the `executable_callback` argument
                         must be provided.

  `executable_callback  `  A |String| or |Funcref| for a callback function
                         accepting a buffer number. A |String| should be
                         returned for the executable to check. This can be
                         used in place of `executable` when more complicated
                         processing is needed.

  `command`                A |String| for an  executable to run asynchronously.
                         This command will be fed the lines from the buffer to
                         check, and will produce the lines of output given to
                         the `callback`.

  `command_callback`       A |String| or |Funcref| for a callback function
                         accepting a buffer number. A |String| should be
                         returned for a command to run. This can be used in
                         place of `command` when more complicated processing
                         is needed.

                         If an empty string is returned from the callback,
                         no jobs for linting will be run for that linter.
                         This can be used for skipping a linter call,
                         say if no configuration file was found.

  `command_chain`          A |List| of |Dictionary| items defining a series
                         of commands to be run. At least one |Dictionary|
                         should be provided. Each Dictionary must contain the
                         key `callback`, defining a |String| or |Funcref| for
                         a function returning a |String| for a command to run.

                         The callback functions for each command after the
                         first command in in the chain should accept two
                         arguments `(buffer, output)`, a buffer number and a
                         |List| of lines of output from the previous command
                         in the chain.

                         The first callback function in a chain accepts only
                         a `(buffer)` argument, as there are no previous
                         commands to run which return `output`.

                         If an empty string is returned for a command in a
                         chain, that command in the chain will be skipped,
                         and the next function in the chain will be called
                         immediately instead. If the last command in a chain
                         returns an empty string, then no linting will be
                         performed.

                         Commands in the chain will all use the
                         `output_stream` value provided in the root
                         |Dictionary|. Each command in the chain can also
                         provide an `output_stream` key to override this value.
                         See the `output_stream` description for more
                         information.

                         Commands in the chain all behave as if `read_buffer`
                         is set to `0` by default, except for the last command
                         in the chain, which uses the value set for
                         `read_buffer` in the root |Dictionary|. Each command
                         in the chain can also provide a `read_buffer` key
                         to override these values.
                         See the `read_buffer` description for more
                         information.

  `output_stream`          A |String| for the output stream the lines of output
                         should be read from for the command which is run. The
                         accepted values are `'stdout'`, `'stderr'`, and
                         `'both'`. This argument defaults to `'stdout'`. This
                         argument can be set for linter programs which output
                         their errors and warnings to the stderr stream
                         instead of stdout. The option `'both'` will read
                         from both stder and stdout at the same time.

  `read_buffer`            A |Number| (`0` or `1`) indicating whether a command
                         should read the Vim buffer as input via stdin. This
                         option is set to `1` by default, and can be disabled
                         if a command manually reads from a temporary file
                         instead, etc.

  `lint_file`              A |Number| (`0` or `1`) indicating whether a command
                         should read the file instead of the Vim buffer. This
                         option can be used for linters which must check the
                         file on disk, and which cannot check a Vim buffer
                         instead.

                         Linters set with this option will not be run as a
                         user types, per |g:ale_lint_on_text_changed|. Linters
                         will instead be run only when events occur against
                         the file on disk, including |g:ale_lint_on_enter|
                         and |g:ale_lint_on_save|. Linters with this option
                         set to `1` will also be run when linters are run
                         manually, per |ALELint-autocmd|.

                         When this option is set to `1`, `read_buffer` will
                         be set automatically to `0`. The two options cannot
                         be used together.

  Only one of `command`, `command_callback`, or `command_chain` should be
  specified. `command_callback` is generally recommended when a command string
  needs to be generated dynamically, or any global options are used.
  `command_chain` is recommended where any system calls need to be made to
  retrieve some kind of information before running the final command.

  If temporary files or directories are created for commands run with
  `command_callback` or `command_chain`, then these tempoary files or
  directories can be managed by ALE, for automatic deletion.
  See |ale#engine#ManageFile()| and |ale#engine#ManageDirectory| for more
  information.

  All command strings will be formatted for special character sequences.
  Any substring `%s` will be replaced with the full path to the current file
  being edited. This format option can be used to pass the exact filename
  being edited to a program.

  For example: >
  'command': 'eslint -f unix --stdin --stdin-filename %s'
<
  Any substring `%t` will be replaced with a path to a temporary file. Merely
  adding `%t` will cause ALE to create a temporary file containing the
  contents of the buffer being checked. All occurrences of `%t` in command
  strings will reference the one temporary file. The temporary file will be
  created inside a temporary directory, and the entire temporary directory
  will be automatically deleted, following the behaviour of
  |ale#engine#ManageDirectory|. This option can be used for some linters which
  do not support reading from stdin.

  For example: >
  'command': 'ghc -fno-code -v0 %t',
<
  The character sequence `%%` can be used to emit a literal `%` into a
  command, so literal character sequences `%s` and `%t` can be escaped by
  using `%%s` and `%%t` instead, etc.

  If a callback for a command generates part of a command string which might
  possibly contain `%%`, `%s`, or `%t` where the special formatting behaviour
  is not desired, the |ale#engine#EscapeCommandPart()| function can be used to
  replace those characters to avoid formatting issues.


ale#linter#Get(filetype)                                     *ale#linter#Get()*

  Return all of linters configured for a given filetype as a |List| of
  |Dictionary| values in the format specified by |ale#linter#Define()|.

  Filetypes may be dot-seperated to invoke linters for multiple filetypes:
  for instance, the filetype `javascript.jsx` will return linters for both the
  `javascript` and `jsx` filetype.

  Aliases may be defined in as described in |g:ale_linter_aliases|. Aliases
  are applied after dot-seperated filetypes are broken up into their
  components.


ale#statusline#Status()                               *ale#statusline#Status()*

  Return a formatted string that can be added to the statusline.
  The output's format is defined in |`g:ale_statusline_format`|.
  To enable it, the following should be present in your |statusline| settings: >
  %{ale#statusline#Status()}


ALELint                                                       *ALELint-autocmd*

  This |User| autocommand is triggered by ALE every time it completes a lint
  cycle. It can be used to update statuslines, send notifications, or
  complete any other operation that needs to be done after linting has been
  performed.

  For example, you can echo a message when linting is complete like so:
  >
  autocmd User ALELint echom "ALE run!"
<

===============================================================================
7. Special Thanks                                          *ale-special-thanks*

Special thanks to Mark Grealish (https://www.bhalash.com/) for providing ALE's
snazzy looking ale glass logo. Cheers, Mark!

===============================================================================
8. Contact                                                        *ale-contact*

If you like this plugin, and wish to get in touch, check out the GitHub
page for issues and more at https://github.com/w0rp/ale

If you wish to contact the author of this plugin directly, please feel
free to send an email to devw0rp@gmail.com.


Please drink responsibly, or not at all, which is ironically the preference
of w0rp, who is teetotal.



  vim:tw=78:ts=2:sts=2:sw=2:ft=help:norl: