Calcit Scripting Language

Semantically a dialect of ClojureScript. Built with Rust. Compiles to JavaScript ES Modules.

• Home https://calcit-lang.org/
• API Doc https://apis.calcit-lang.org/
• Guidebook https://guide.calcit-lang.org/

Browse examples or also try WASM version online.

Core design:

• Interpreter runs on Rust, extensible with Rust FFI
• Persistent Data Structure
• Structural Editor(with indentation-based syntax as a fallback)
• Lisp macros, functional style
• Compiles to JavaScript in ES Modules, JavaScript Interop
• Hot code swapping friendly

Install

Build and install with Rust:

# get Rust
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

# get Calcit
cargo install calcit

3 binaries are installed:

• calcit, the runtime and js compiler
• caps, for downloading dependencies declared in deps.cirru
• bundle_calcit, bundle code if you don't want to use Calcit Editor

To use Calcit in GitHub Actions, try setup-cr.

Usage

Snippets evaluating:

cr eval 'range 100'

cr eval 'thread-first 100 range (map $ \ * % %)'

Run with a compact.cirru:

cr compact.cirru -1 # run only once

cr -1 # by default, it picks `compact.cirru`

cr # watch mode enabled by default

By default Calcit reads :init-fn and :reload-fn inside compact.cirru configs. You may also specify functions,

cr --init-fn='app.main/main!' --reload-fn='app.main/reload!'

and even configure :entries in compact.cirru:

cr --entry server

JavaScript codegen

It compiles to JavaScript and runs in consistet semantics. However it might require a lot of JavaScript interop.

cr js # compile to js, also picks `compact.cirru` by default
cr js --emit-path=out/ # compile to js and save in `out/`

By default, js code is generated to js-out/. You will need Vite or Node to run it, from an entry file:

import { main_$x_, reload_$x_ } from "./js-out/app.main.mjs";
main_$x_(); // which corresponds to `main!` function in calcit

Calcit Editor & Bundler

Install Calcit Editor and run ct to launch editor server, which writes compact.cirru and .compact-inc.cirru on saving. Try launching example by cloning Calcit Workflow.

Read more in Minimal Calcit to learn how to code Calcit with a plain text editor.

Read more in Respo Calcit Workflow to learn to create an MVC webpage with Respo.

MCP (Model Context Protocol) Support

Calcit provides MCP server functionality for integration with AI assistants and development tools. The MCP server offers tools for:

• Code Management: Read, write, and modify Calcit namespaces and definitions
• Project Operations: Manage modules, dependencies, and configurations
• Calcit Runner: Start/stop background runner processes with incremental updates
• Documentation: Query API docs, reference materials, and dependency documentation

Incremental File Processing

When using the Calcit Runner through MCP:

1. Start Runner: Use start_calcit_runner to launch the background process. This automatically:

   • Creates a .calcit-tmp/ directory
   • Copies the current compact.cirru as a temporary baseline

2. Generate Incremental Updates: After making changes to your code, use generate_calcit_incremental to:

   • Compare current compact.cirru with the temporary baseline
   • Generate a .compact-inc.cirru file with only the changes
   • Apply incremental updates to the running process

3. Check Results: After generating the incremental file, always check the runner logs using grab_calcit_runner_logs to verify that updates were applied successfully.

This workflow enables efficient hot-reloading during development without restarting the entire application.

Modules

deps.cirru declares dependencies that need to download, which correspond to repositories on GitHub. Specify a branch or a tag:

{}
  :calcit-version |0.9.11
  :dependencies $ {}
    |calcit-lang/memof |0.0.11
    |calcit-lang/lilac |main

Run caps to download. Sources are downloaded into ~/.config/calcit/modules/. If a module contains build.sh, it will be executed mostly for compiling Rust dylibs.

:calcit-version helps in check version, and provides hints in CI environment.

To load modules, use :modules configuration and compact.cirru(which normally generated from calcit.cirru):

:configs $ {}
  :modules $ [] |memof/compact.cirru |lilac/

Paths defined in :modules field are just loaded as files from ~/.config/calcit/modules/, i.e. ~/.config/calcit/modules/memof/compact.cirru.

Modules that ends with /s are automatically suffixed compact.cirru since it's the default entry.

Development

I use these commands to run local examples:

# run tests in Rust
cargo run --bin cr -- calcit/test.cirru -1

# run tests in Node.js
cargo run --bin cr -- calcit/test.cirru -1 js && yarn try-js

# run snippet
cargo run --bin cr -- eval 'range 100'

cr compact.cirru -1 ir # compiles intermediate representation into program-ir.cirru

• Cirru Parser for indentation-based syntax parsing.
• Cirru EDN for compact.cirru file parsing.
• Ternary Tree for immutable list data structure.

Other tools:

• Error Viewer for displaying .calcit-error.cirru
• IR Viewer for rendering program-ir.cirru

Some resources:

• Dev Logs https://github.com/calcit-lang/calcit/discussions
• 视频记录 https://space.bilibili.com/14227306/channel/seriesdetail?sid=281171

License

MIT