@gram-lang/format

Canonical code formatter for .gram files, used by both the gram format CLI command and the VS Code extension / Language Server. It unifies 13 formatting rules into a single deterministic pass.

formatGram

function formatGram(source: string, options?: FormatterOptions): string

Formats a .gram source string according to Gram’s 13 canonical formatting rules.

import { formatGram } from '@gram-lang/format';

const formatted = formatGram(`
---
title: 'Crepes'
---

## Batter
Mix @flour{200g}  and  @milk{200ml}.
`);

FormatterOptions

interface FormatterOptions {
  tabSize?: number;      // Number of spaces per tab level (default: 2)
  insertSpaces?: boolean; // Use spaces instead of tabs (default: true)
}

Formatting rules

formatGram applies 13 deterministic formatting rules:

1. Frontmatter: Preserves frontmatter delimiters (---) and cleans up leading/trailing whitespace around metadata.
2. Section Headings: Ensures a single space after ## section titles (e.g. ## Section).
3. Step Indexing: Formats numbered step prefixes cleanly (1. Step text).
4. Action Blocks: Formats step action prefixes ([Mix] ...).
5. Ingredient Tokens: Normalizes @ingredient{qty} spacing and bracket syntax.
6. Cookware Tokens: Normalizes #cookware{qty} spacing and bracket syntax.
7. Timer Tokens: Normalizes ~timer{duration} and passive ~_timer{duration} spacing.
8. Temperature Tokens: Normalizes ^temp{value} syntax.
9. Intermediate Declarations & References: Normalizes ->&dough declarations and &dough references.
10. Composite Syntax: Normalizes <@parent composite ingredient syntax.
11. Decimal Quantities: Normalizes numeric decimal quantities (e.g. trimming trailing zeros like 1.50 -> 1.5).
12. Comment Formatting: Ensures clean spacing after comment sigils (// comment).
13. Whitespace Cleanup: Trims trailing whitespace per line and ensures a single trailing newline.

FormatterChanges

Returns structured metrics on formatting edits made (useful for editor extensions and reporting):

interface FormatterChanges {
  formatted: string;
  hasChanges: boolean;
  rulesApplied: string[];
}