language-detect

Fast, evidence-based programming language detection for projects.

Philosophy

• Evidence-based - Shows WHY each language was detected (markers + file counts)
• Fast scanning - Checks markers first, falls back to extension counts
• Composable output - JSON pipes to jq, other tools, CI/CD
• Useful standalone - Debugging, scripts, tool integration

Installation

# Install globally
cd packages/language-detect
bun link

# Or run directly with bun
bun language-detect.ts /path/to/project

Usage

# Detect languages in current directory
language-detect .

# Detect in specific project
language-detect /path/to/project

# List detected languages only
language-detect . | jq -r '.languages[]'

# Show evidence for specific language
language-detect . | jq '.markers.typescript'

# Check if project uses Go
language-detect . | jq -e '.languages[] | select(. == "go")'

Detection Strategy

Phase 1: Marker files (fast, reliable)

• Python: pyproject.toml, requirements.txt, setup.py, Pipfile
• JavaScript/TypeScript: package.json, tsconfig.json
• Go: go.mod, go.sum
• Rust: Cargo.toml, Cargo.lock
• Ruby: Gemfile, Gemfile.lock
• etc.

Phase 2: Extension fallback (when no markers)

• Counts files with language extensions (.ts, .py, .go, etc.)
• Configurable threshold (default: any files detected)
• Scans up to 3 directory levels deep
• Skips hidden directories for performance

Output Format

{
  "languages": ["typescript"],
  "markers": {
    "typescript": ["7 *.ts files"]
  }
}

Supported Languages

• Python
• JavaScript
• TypeScript
• Go
• Rust
• Ruby
• Java
• C#
• PHP
• Swift
• Kotlin
• Scala

Configuration

Edit EXTENSION_THRESHOLD in language-detect.ts:

• 0 = detect any files (default)
• 3 = need 3+ files
• Higher values = more conservative detection

Exit Codes

• 0 - Success (languages detected or none found)
• 2 - Error (invalid args, directory not found)