path: root/doc/ale.txt

*ale.txt*  For Vim version 8.0.  Last change: 2016 October 5
*ale*

ALE - Asychronous Lint Engine

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

  1. Introduction...................................|ale-introduction|
  2. Supported Languages & Tools....................|ale-support|
  3. Global Options.................................|ale-options|
  4. Linter Specific Options........................|ale-linter-options|
    4.1. eslint................................ ....|ale-linter-options-eslint|
  5. API............................................|ale-api|
  6. 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.

* Bash: 'shell' (-n flag), 'shellcheck'
* Bourne Shell: 'shell' (-n flag), 'shellcheck'
* C: 'gcc'
* CoffeeScript: 'coffelint'
* CSS: 'csslint'
* D: 'dmd'
* Fortran: 'gcc'
* Haskell: 'ghc'
* HTML: 'tidy'
* JavaScript: 'eslint', 'jscs', 'jshint'
* JSON: 'jsonlint'
* PHP: 'php' (-l flag), 'phpcs'
* Python: 'flake8'
* Ruby: 'rubocop'
* SASS: 'sasslint'
* SCSS: 'sasslint', 'scsslint'
* TypeScript: 'tslint'
* Vim: 'vint'
* YAML: 'yamllint'

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

g:ale_linters                                                   *g:ale_linters*

Type: |Dictionary|
Default: unset

  The |g:ale_linters| option sets a |Dictionary| mapping a filetype
  to a |List| of linter programs to be run when checking particular filetypes.
  By default, this dictionary will not be set at all, and all possible
  linter programs will be run for a given filetype, if the linter programs
  are found to be |executable|.

  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': []}
<

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_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_save                                         *g:ale_lint_on_save*

Type: |Number|
Default: `0`

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_set_loclist                                           *g:ale_set_loclist*

Type: |Number|
Default: `1`

When this option is set to `1`, the |loclist| will be populate 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_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_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_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_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.


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 Specific Options                                 *ale-linter-options*

Some linters have specific options which can be configured for each of them,
for customising their behaviour.

-------------------------------------------------------------------------------
4.1. eslint

g:ale_javascript_eslint_executable         *g:ale_javascript_eslint_executable*

Type: |String|
Default: `'eslint'`

This variable can be changed to change the path to eslint. If you have
eslint_d installed, you can set this option to use eslint_d instead.

===============================================================================
5. API                                                                *ale-api*

ALELint(delay)                                                      *ALELint()*
  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

ALEAddLinter(filetype, linter)                                 *ALEAddLinter()*
  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.

  `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`.

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

  `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.

  `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'` and `'stderr'`. 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.

  Some programs for checking for errors are not capable of receiving input
  from stdin, as is required by ALE. To remedy this, a wrapper script is
  provided named in the variable |g:ale#util#stdin_wrapper|. This variable
  can be called with the regular arguments for any command to forward data
  from stdin to the program, by way of creating a temporary file. The first
  argument to the stdin wrapper must be a file extension to save the temporary
  file with, and the following arguments are the command as normal.
  For example: >
  'command': g:ale#util#stdin_wrapper . ' .hs ghc -fno-code -v0',
<

ALEGetLinters(filetype)                                       *ALEGetLinters()*
  Return all of linters configured for a given filetype as a |List| of
  |Dictionary| values in the format specified by |ALEAddLinter()|.

g:ale#util#stdin_wrapper                             *g:ale#util#stdin_wrapper*
  This variable names a wrapper script for sending stdin input to programs
  which cannot accept input via stdin. See |ALEAddLinter| for more.

===============================================================================
6. 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.



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