Deed MCP server

A contract-first language where a function signature is a promise the compiler checks. Built for code that machines write and humans review.

Status: the toolchain works; adoption is the open question. The compiler lexes,

parses, resolves names, checks types, contracts and effect rows, and runs programs through

either the reference interpreter or a WebAssembly backend. deed build writes a core

module, and --component writes a component when its exported values cross the canonical

ABI. Programs get authority from explicit capabilities, with the same host rules in both

engines. The largest unfinished technical work is value reclamation and wider component

adapters; the largest project risk is simpler and measured: no public repository outside

this organization contains known Deed source yet. ROADMAP.md keeps that

distinction and the commands that measure it.

Getting it

One line, on Linux or an Apple-silicon Mac:

$ curl -fsSL https://raw.githubusercontent.com/deed-lang/deed/main/install.sh | sh

On Windows:

> irm https://raw.githubusercontent.com/deed-lang/deed/main/install.ps1 | iex

Either one downloads the release asset for your machine, refuses it if its hash is not the one the release published, and puts a single file in your own profile. It never asks for a password, because it never writes outside it. The checksums come from the same release as the binary, so that catches a corrupted download and does not catch a compromised release; saying so is better than a sha256 that reads like it proves more than it does.

By hand instead: every release carries a deed binary for Linux, macOS and Windows. Take the one for your machine from releases, unpack it, and run it. There is nothing else to install: the compiler, the formatter, the test runner and the language server are all in that one file.

Start with the tutorial if you want one program built up one step at a time.

$ tar xzf deed-v0.2.13-x86_64-unknown-linux-gnu.tar.gz
$ ./deed-v0.2.13-x86_64-unknown-linux-gnu/deed --version
deed 0.2.13

With Rust 1.88 or newer instead, from crates.io or from a clone:

$ cargo install deed-lang
$ cargo install --path crates/deed-cli

deed on crates.io belongs to somebody else, so the package is deed-lang. The binary it installs is deed; the package README keeps the short install and MCP entry points next to the package metadata.

What the version promises. 0.x says the language can still move, so a file that compiles against one minor release may not compile against the next. Breaking moves are called out in release notes, and deed fix carries the mechanical part when possible. The full policy, including diagnostics and std/, is in design/07-versioning.md.

Starting something

deed new writes a project rather than leaving you to work out the module header and the file layout from this repository. The name becomes both the directory and the module path.

$ deed new greeter
greeter/greeter.deed
greeter/main.deed

next: cd greeter && deed test .

$ cd greeter
$ deed test .
./greeter.deed
  ok    a greeting carries the name it was given
  ok    there is no greeting for nobody
  ok    property greeting (100 cases)

3 passed, 0 failed

$ deed run main.deed
hello, world

Three tests from two files, and only two of them were written down. The third is generated from the contract on greeting, which is what a signature being a promise buys. There is no manifest, because a manifest here says where code outside your tree lives and a new project has none.

Shortened. The full README is on GitHub.