Gleam Tooling and Formatting

Gleam ships with a complete built-in toolchain. One CLI handles every task — formatting, building, testing, documentation generation, and package management. No extra tools to install, no configuration files to write, no version conflicts between linter and compiler.

The gleam CLI — Full Reference

gleam CLI Commands
──────────────────────────────────────────────────
Project Management:
  gleam new <name>          Create a new project
  gleam add <package>       Add a dependency
  gleam remove <package>    Remove a dependency
  gleam deps download        Install all dependencies
  gleam deps update          Update dependency versions

Build and Run:
  gleam build                Compile the project
  gleam run                  Compile and run main()
  gleam run -m <module>     Run a specific module
  gleam test                 Run all tests
  gleam clean                Delete build artifacts

Code Quality:
  gleam format               Format all .gleam files
  gleam check                Type-check without building
  gleam fix                  Auto-fix certain warnings

Documentation:
  gleam docs build           Build HTML documentation
  gleam docs serve           Serve docs in browser
  gleam docs publish         Publish docs to HexDocs

Publishing:
  gleam publish              Publish to Hex package registry
  gleam hex authenticate     Log in to Hex

gleam format — Automatic Code Formatting

Gleam has one official style. The formatter enforces it with no configuration:

gleam format              // format all .gleam files in src/ and test/
gleam format src/user.gleam  // format one specific file
gleam format --check      // check without modifying (use in CI)

Before formatting:
──────────────────────────────────────────────────
pub fn add(  a:Int,b :Int)->Int{a+b}

After gleam format:
──────────────────────────────────────────────────
pub fn add(a: Int, b: Int) -> Int {
  a + b
}

The formatter handles indentation, spacing, line breaks, and import ordering. Every Gleam codebase looks identical — no style debates, no reviewer comments about formatting, no inconsistency across team members.

gleam check — Fast Type Checking

gleam check

Type-checks your code without producing output files. Much faster than a full build when you just want to verify types during development. Useful in editor save hooks and pre-commit checks.

gleam docs — Documentation Generation

Gleam generates HTML documentation from doc comments automatically:

/// Calculates the area of a rectangle.
///
/// ## Examples
///
/// ```gleam
/// area(5.0, 3.0)
/// // → 15.0
/// ```
pub fn area(width: Float, height: Float) -> Float {
  width *. height
}

Doc Comment Syntax
──────────────────────────────────────────────────
///  → doc comment (appears in generated HTML docs)
//   → regular comment (not included in docs)

Support Markdown:
  ## Section headings
  `code inline`
  ```gleam
  code blocks with syntax highlighting
  ```
  - bullet lists

gleam docs build    // generates HTML in build/docs/
gleam docs serve    // opens docs in browser at localhost:7070

Language Server (LSP)

The Gleam Language Server provides editor intelligence. The gleam CLI installs it automatically when you install Gleam:

LSP Features
──────────────────────────────────────────────────
✓ Syntax highlighting
✓ Real-time type error underlining
✓ Inline type information on hover
✓ Auto-complete for functions, types, modules
✓ Go to definition
✓ Find all references
✓ Rename refactoring
✓ Code actions (add import, fix warnings)
✓ Format on save

Editor Setup

Editor         Extension / Config
──────────────────────────────────────────────────
VS Code        Install "Gleam" extension from marketplace
Neovim         Use nvim-lspconfig with gleam LSP
Helix          Built-in LSP support for Gleam
Zed            Built-in Gleam support
Emacs          gleam-mode + lsp-mode
Sublime Text   LSP + LSP-gleam package

Setting Up CI/CD

A minimal GitHub Actions pipeline for a Gleam project:

# .github/workflows/ci.yml
name: CI

on: [push, pull_request]

jobs:
  test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Install Erlang
        uses: erlef/setup-beam@v1
        with:
          otp-version: "26"

      - name: Install Gleam
        run: |
          curl -L https://github.com/gleam-lang/gleam/releases/download/v1.5.1/gleam-v1.5.1-x86_64-unknown-linux-musl.tar.gz | tar xz
          sudo mv gleam /usr/local/bin/

      - name: Check formatting
        run: gleam format --check

      - name: Type check
        run: gleam check

      - name: Run tests
        run: gleam test

Project Configuration Tricks

gleam.toml Options
──────────────────────────────────────────────────
name = "my_app"
version = "1.0.0"
description = "A great Gleam application"
licences = ["Apache-2.0"]
repository = { type = "github", user = "you", repo = "my_app" }
links = [{ title = "Website", href = "https://myapp.dev" }]
target = "erlang"          # or "javascript"

[dependencies]
gleam_stdlib = ">= 0.36.0 and < 2.0.0"

[dev-dependencies]
gleeunit = ">= 1.1.0 and < 2.0.0"

Useful gleam run Flags

gleam run --target javascript    // compile and run with Node.js
gleam run -m module_name         // run a specific module's main()
gleam test --target javascript   // run tests in JS environment
gleam build --target javascript  // JS-only build

Key Points

Tooling Essentials
──────────────────────────────────────────────────
1. gleam format  → auto-format (no config needed)
2. gleam check   → fast type check only
3. gleam test    → run all tests
4. gleam docs build → generate HTML docs from /// comments
5. gleam format --check → CI formatting enforcement
6. LSP installed automatically — plug into any editor
7. gleam.toml   → project metadata and dependencies
8. One tool handles everything — no npm/webpack/eslint juggling

The Gleam toolchain removes the setup friction that plagues many language ecosystems. One binary, one command for each task, zero configuration required. Teams spend their time writing and shipping Gleam code rather than configuring build tools.