taohe

Move smart contracts implementing nestable resources on MoveVM blockchains

View on GitHub

▣ TaoHe: Collection of nestable Move resources

Mentioned in Awesome Move GitHub Movey

TaoHe is a collection of nestable smart contract resources that can be used to create secure on-chain applications on various Move-powered blockchains. Resources can be nested like a Russian doll (матрёшка), or Chinese boxes (套盒), the namesake of this project. ▣ is used as the logo, since it depicts a box inside another box.

Tao is a simple Move resource that has been designed to be nested inside other taos. TaoHe is a collection of taos, and a special Root resource that can be used to store a resource directly into an account (taos themselves can be stored into resources only, for simplicity).

TaoHe follows the Nestable Resources software design pattern.

Example: Tokens can be placed into a time locked resource (Timelock), which in turn can be placed into a resource which can be used only by a certain user (Ownable), effectively creating a timelocked non-fungible token.

See TaoHe on Movey, the package metadata repository for Move. Archived version of the original announcement can be found here.

Design

What taos are

Taos are meant to form disposable structures that contain a meaningful resource (such as tokens). In order to access the resource in question, taos must be dismantled. A new tao can be created though, if so desired. Nesting taos inside each other can form complicated logics, such as timelocked non-fungible tokens.

Why taos are small

Keeping code footprint per each tao in minimum is vital for safer code, and is simpler to audit. Keeping taos simple also shifts the code footprint to scripts, which are easier to develop and update than smart contracts.

Tao lifespan

Tao’s lifespan is divided into three separate phases, listed here chronologically:

What taos are not

Taos are not meant to replace specialized smart contract development for complicated applications, but can be used as part of one.

Building and developing

TaoHe is developed with Microsoft’s Visual Studio Code and the move-analyzer plugin.

We use Move CLI (HEAD: b53bb03) for building, package management, dependencies, formal verification and testing. After building the Docker image, you can just issue:

alias move="docker run -v \`pwd\`:/project move/cli"

on your POSIX system to get the move command.

Jumpstart: move sandbox publish && move sandbox run -v scripts/folder.move --signers 0xA (replace folder with any function residing in scripts/)

Selecting blockchain

TaoHe is designed to support every Move powered blockchain. This is achieved by Connectors, which is a thin middleware between TaoHe and the desired target blockchain. At the moment only the Dummy Connector is available for easier testing and development, but you can search GitHub for other Move Connectors.

To change the connector, replace the Connector dependency with your desired connector in your Move.toml.

Formal verification

Every tao has formal verification specs embedded. You can run the formal verification by running:

move prove

Learn more about installing the formal verification tools and dependencies here.

Warning: Although every tao has formal verification specs, move-prover is still under development, and might have some limitations. Please see each source file for more information.

Using TaoHe for your projects

You can also add TaoHe as a dependency for your Move project by adding these lines to your project’s Move.toml:

[dependencies.TaoHe]
git = "https://github.com/taoheorg/taohe"
addr_subst = { "TaoHe" = "0x2f66c09143acc52a85fec529a4e20c85" }
rev="...."

Warning: Due to signed commits, commit hash should be used since it cannot be spoofed. After you know which TaoHe version you want to use, replace rev with your desired commit hash.

Known problems

Poor developer experience

DX is not good at the moment since types must be known beforehand, and written in their full form, resulting in lengthy inscrutable lines of code. This could be solved by creating an intermediate Yaml based description language which could be used to generate transaction scripts and transaction script functions (a new Move feature).

Documentation

See doc/ for move docgen generated documentation.

License

This repository is released under the Apache License 2.0, and is copyrighted to Solarius Intellectual Properties Ky (Forssa, Finland, EU). See Move.toml for more information on dependencies. No warranty or fitness for a particular purpose provided, as stipulated in the License.

Trusted source

Smart contracts are mission critical and as such should always originate from trusted sources. That’s why every commit on main is signed with Ville’s GPG key. Upstream repository is here and the official webpage is at www.taohe.org.