Candid

Candid is an interface description language (IDL) for interacting with canisters (also known as services or actors) running on the Internet Computer. It provides a language-independent description of canister interfaces and the data they exchange, with type safety and extensibility.

Documentation

• The spec directory contains Candid specifications, including the Candid language specification and a soundness proof.
• The official manual is hosted by dfinity; see ./docs for the source code.

Implementations

Candid supports several different programming languages. This repository contains some of the implementations developed by DFINITY.

• Rust: A serialization library based on Serde, and a compiler for generating bindings for other languages.
• Motoko: Compiler support for importing/export Candid files. Also see the Motoko-Candid type mapping specificatoin.
• JavaScript: We provide a library for serialization of native JavaScript values, and a visitor class for extending Candid for building generic tools such as UI and random testing.

A list of community maintained Candid libraries:

• Haskell
• Elm
• Kotlin
• AssemblyScript
• Java
• Dart
• Motoko
• C#

Tools

• didc: Candid CLI. Download prebuilt binary.
• candiff: Diff Candid values structurally
• ui: Candid UI canister. See deployed canister on the IC
• ic-repl: A REPL environment to communicate with canisters using Candid

Tests

We provide a test suite to check Candid implementations for compliance.

Release

To make a release in this repo:

• Update Changelog.md and merge the PR into master.
• git tag 2020-04-01 -m "2020-04-01"
• git push origin 2020-04-01

The tag is always today's date. As the repo contains several targets, it is hard to give a version to the tag.

Contribution

See our CONTRIBUTING and CODE OF CONDUCT to get started.