Exlint

Elixir syntax checker.

Why should I use this

elixirc executes all function calls in the top level scope. This means that all elixir files, not just .exs are treated as executables by the compiler.

This is an intentional design, and nessicary for the macro system to work.

Becaused of this compiling a file, like the example below, can have destructive operations on the filesystem.

File.write("sup", "sup")

defmodule Foo do
end

_Compiling this file results in a file called sup being written to the current working directory.

A further discussion is available here

Previous syntax checking plugins for elixir were removed because of this behaviour.

exlint which reports syntax problems, without executing code in the top level block, however this can't guard against destructive operations in macros.

It works by removing everything from the ast in the top level that isn't a definition, import, or alias before compilitation.

You can intergrate it into vim and ale with something like the following:

function! ExlintCallback(buffer, lines)
  " Matches patterns line the following:
  "
  " lib/filename.ex:19:7: F: Pipe chain should start with a raw value.
  "
  " lib/battle_snake/game_server/server.ex:251:1:4: E: unexpected token: end

  let l:patterns = [
        \ '\v:(\d+):?(\d+)?:?(\d+)?: (.): (.+)$',
        \ ]

  let l:output = []

  for l:match in ale#util#GetMatches(a:lines, l:patterns)
    let l:type = l:match[4]
    let l:text = l:match[5]

    call add(l:output, {
          \   'bufnr': a:buffer,
          \   'lnum': l:match[1] + 0,
          \   'col': l:match[2] + 0,
          \   'end_col': l:match[3] + 0,
          \   'type': l:type,
          \   'text': l:text,
          \})
  endfor

  return l:output
endfunction

function! ExlintCommand(buffer)
  return "exlint %s"
endfunction

call ale#linter#Define('elixir', {
      \   'name': 'elixir',
      \   'executable': 'exlint',
      \   'command_callback': 'ExlintCommand',
      \   'callback': 'ExlintCallback',
      \})