Formatter

The Draft formatter (draft fmt) enforces consistent code style.

Usage

Format Files

@// Format single file
draft fmt main.draft

@// Format directory
draft fmt src/

@// Format all files in project
draft fmt

Check Formatting

draft fmt --check

Exit code 1 if files need formatting.

Show Diff

draft fmt --diff

Configuration

draft.toml

[format]
line_width = 100
indent_size = 4
use_tabs = false
trailing_comma = true
newline_style = "Unix"

.draftfmt

Create a .draftfmt file in the project root:

line_width = 100
indent_size = 4
use_tabs = false
trailing_comma = true
single_line_if = false

Formatting Rules

Indentation

Default: 4 spaces

action example()
    if @condition
        do_something()
    else
        do_other()
    fin if.
fin action.

Line Width

Default: 100 characters

Lines exceeding the limit are wrapped:

@// Before formatting
@result = @math#sqrt(@a * @a + @b * @b + @c * @c + @d * @d)

@// After formatting
@result = @math#sqrt(
    @a * @a + @b * @b + @c * @c + @d * @d
)

Blank Lines

@// Between top-level definitions
action first()
    @// ...
fin action.

action second()
    @// ...
fin action.

Trailing Commas

@// Trailing commas in multi-line
@list = [
    1,
    2,
    3,
]

@map = {
    "a", 1,
    "b", 2,
}

String Quotes

@// Consistent string quotes
@name = "Alice"
@greeting = "Hello, World!"

Comment Formatting

@// Single-line comments have space after //

@/*
 * Multi-line comments
 * are aligned
 */

Import Sorting

@// Imports are sorted alphabetically
import collections
import fs
import http
import io
import json
import math
import process
import strings
import time

Import Grouping

@// Standard library imports
import io
import fs
import math

@// Third-party imports
import http

@// Local imports
import { User } from ./models/user

Record Formatting

record User
    name: String
    age: Int
    email: String
fin record.

Action Formatting

action add(@a: Int, @b: Int) -> Int
    return @a + @b
fin action.

If-Else Formatting

if @condition
    do_something()
else if @other_condition
    do_other()
else
    fallback()
fin if.

Loop Formatting

for @item in @items
    process(@item)
fin for.

while @condition
    update()
fin while.

Match Formatting

match @value
    when String then handle_string(@value)
    when Int then handle_int(@value)
    when Boolean then handle_bool(@value)
    else handle_other(@value)
fin match.

Ignoring Code

Skip Formatting

@// draftfmt:off
@x=1
@y=2
@z=3
@// draftfmt:on

Skip File

@// draftfmt:file:off

Editor Integration

VS Code

{
    "editor.formatOnSave": true,
    "[draft]": {
        "editor.defaultFormatter": "draft-lang.draft"
    }
}

Vim

autocmd FileType draft setlocal formatprg=draft\ fmt\ -

Emacs

(add-hook 'draft-mode-hook
    (lambda () (setq format-all-mode t)))

CI Integration

GitHub Actions

name: Format Check
on: [push, pull_request]
jobs:
  format:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: draft-lang/setup-draft@v1
      - run: draft fmt --check

Pre-commit Hook

repos:
  - repo: https://github.com/draft-lang/draft
    rev: v1.4.0
    hooks:
      - id: draft-fmt

Exit Codes

Code	Meaning
0	Success / Already formatted
1	Files need formatting (with –check)
2	Error