Vim Ale Linter Error

In this tutorial, you'll learn about How to Fix Vim ALE Linter Errors. We cover key concepts, practical examples, and best practices.

The Problem

ALE is not showing any linting errors:

:ALEInfo
...
No linters found for filetype 'python'

Quick Fix

Step 1: Install ALE

Plug 'dense-analysis/ale'

Then vim +PlugInstall +qall.

Step 2: Check available linters

:ALEInfo
:ALEList

Step 3: Install the required linter

pip install flake8 pylint mypy
npm install -g eslint
sudo apt install shellcheck

Step 4: Configure ALE

let g:ale_linters = {
\   'python': ['flake8', 'mypy'],
\   'javascript': ['eslint'],
\}
let g:ale_fixers = {
\   'python': ['black', 'isort'],
\}
let g:ale_fix_on_save = 1
let g:ale_sign_column_always = 1

Step 5: Use key mappings

nmap <silent> <C-k> <Plug>(ale_previous_wrap)
nmap <silent> <C-j> <Plug>(ale_next_wrap)

Step 6: Enable linting on text change

let g:ale_lint_on_text_changed = 'always'
let g:ale_lint_on_insert_leave = 1

Prevention

• Install at least one linter per language you use.
• Run :ALEInfo to debug which linters ALE finds.
• Keep linters updated.

Common Mistakes with ale linter error

1. Using return to exit a function early instead of wrapping a pure value in the monad
2. Mixing let bindings with <- bindings in do notation, producing type errors
3. Overlapping type class instances that cause GHC to reject the program with ambiguous dispatch errors

These mistakes appear frequently in real-world VIM code. DodaTech's contributors have identified these patterns through analysis of open-source projects and production systems.

Practice Exercise

Write a pure function that safely divides two integers using Maybe, then test it with edge cases like division by zero and negative numbers.

This exercise reinforces the concepts covered in this guide. Try implementing it before checking online solutions.

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