Tacit: An LLM-First Programming Language Built with Claude Code and Opus 4.7

Tacit is a new experimental LLM-first programming language built with Claude Code and Opus 4.7. The core idea: design a language that plays to LLM strengths and removes unnecessary human conveniences, aiming for fewer tokens in generated code.

Key Features

• LLM Primer: The toolchain includes a "primer" that teaches mid-tier or higher LLMs (Sonnet and above) how to write Tacit code. This is not a compiler but a learning mechanism for the model.
• Multiple Source Code Views: Supports task-specific views of the abstract syntax tree (AST), allowing different representations of the same program depending on the task.
• Standard Library, Testing, Packaging: Comes with a standard library, unit testing support, package management, and dependency resolution.
• Hostable in C/Rust: The language runtime can be embedded as a binary written in another language (C or Rust mentioned).

Token Efficiency

One of the explicit goals was to reduce token count. According to the creator, Tacit succeeded in some areas and failed in others. No specific benchmarks are provided, but token optimization is a central design consideration.

Try It Yourself

The blog post (linked in the source) includes instructions on how to experiment with Tacit using your own LLM model. The primer and toolchain are publicly available.

This is early-stage, but it's a concrete attempt at rethinking programming languages for current-generation LLMs — not just wrapping existing languages with prompts.