3TL Python Validator

Python validator for 3TL (Typed Talking To LLMs) format using the Lark parsing library.

Features

• Full Unicode support
• Validates against the complete 3TL grammar
• Case-insensitive type names
• Detailed error messages with line and column numbers
• Optional parse tree visualization

Installation

pip install -r requirements.txt

Usage

Validate a file

python validator.py examples/products.3tl

Validate a string

python validator.py --string "#! Test
#@ id:uint, name:str
1, Alice
"

Show parse tree

python validator.py --show-tree file.3tl

Use custom grammar

python validator.py --grammar custom-grammar.lark file.3tl

Exit Codes

• 0: Valid 3TL format
• 1: Invalid format or error

Examples

Valid:

$ python validator.py ../examples/blog.3tl
Valid 3TL format

Invalid:

$ python validator.py --string "#@ id:uint"
Invalid: Unexpected character at line 1, column 1
  #@ id:uint
  ^
Expected: {'LINE_BREAK', '__ANON_0', 'COMMENT_START'}

Grammar

The validator uses the Lark EBNF grammar defined in ../3tl-grammar.lark. The grammar supports:

• Unicode identifiers (café, 名前, etc.)
• Case-insensitive type names (int, INT, Int all valid)
• Flexible array/nullable modifiers (int[]?, int?[])
• Comments anywhere in the file
• Multiple tables per file
• Foreign key references and enums