Quick Start

Get running with mlld in 5 minutes.

Install

npm install -g mlld

Set Up Your Tools

Install the mlld skill so your LLM coding assistant can help you write mlld:

mlld skill install

This gives Claude Code (and other supported tools) the ability to understand mlld syntax, generate scripts, and help you debug.

Two other commands you'll use constantly:

mlld howto <keyword>       # Search docs by keyword (fuzzy matches titles, tags, content)
mlld validate <file|dir>   # Instant syntax check — catches errors before you run

mlld howto is your go-to reference. Try mlld howto import, mlld howto for, mlld howto security — it covers everything.

Your First Script

Create hello.mld:

var @name = "World"
show `Hello, @name!`

Run it:

mlld hello.mld

Output:

Hello, World!

That's it. var creates variables (always @-prefixed), backticks do string interpolation, show prints output.

Load Files

Angle brackets load file contents:

var @readme = <README.md>
var @config = <package.json>
show `Project: @config.name`

Globs load multiple files:

var @docs = <src/**/*.ts>
show `Found @docs.length() files`

Call an LLM

This is what mlld is for. Install the Claude module and call it:

mlld install @mlld/claude

import { @haiku } from @mlld/claude

var @code = <src/app.ts>
var @review = @haiku(`Review this code for bugs:\n\n@code`)
show @review

@haiku and @sonnet are callable functions. You pass them a prompt, they return the response.

Functions

Define reusable functions with exe:

exe @greet(name) = `Hello, @name!`
exe @add(a, b) = js { return a + b }

show @greet("World")
show @add(2, 3)

Add the llm label to functions that call an LLM — this enables automatic caching and resume:

import { @haiku } from @mlld/claude

exe llm @summarize(file) = @haiku(`Summarize in one sentence:\n\n@file`)

Control Flow

Iterate with for, branch with when:

var @names = ["Alice", "Bob", "Charlie"]
for @name in @names => show `Hello, @name!`

var @score = 85
when @score >= 90 => show "Excellent!"
when @score >= 70 => show "Good job!"
when @score < 70  => show "Keep trying!"

Run Shell Commands

Execute shell commands and capture results:

var @branch = run cmd {git branch --show-current}
show `On branch: @branch`

run sh {
  npm test && echo "Tests passed!" || echo "Tests failed!"
}

cmd for simple pipe-safe commands, sh for full shell scripts. Also js, node, and py for other languages.

A Real Example

Put it together — summarize every TypeScript file in a project:

import { @haiku } from @mlld/claude

exe llm @summarize(file) = @haiku(`Summarize in one sentence:\n\n@file`)

var @files = <src/*.ts>
var @summaries = for @f in @files [
  let @summary = @summarize(@f)
  => `- **@f.mx.filename**: @summary`
]
show @summaries.join("\n")

This loads every .ts file, sends each to an LLM, and collects the results. The llm label on @summarize means results are cached — rerun the script and only new/changed files get re-processed.

Next Steps

You know enough to start building. When you need more:

mlld howto <keyword>       # Search any topic
mlld howto import          # Modules and imports
mlld howto security        # Prompt injection defense
mlld howto mcp             # MCP tool integration
mlld howto                 # Browse all topics
mlld validate .            # Validate your whole project

Run mlld qs anytime to see a condensed syntax reference.