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Subscript: Substrate smart contact written in AssemblyScript

  • Proposer: synote
  • Payment Address: bc1qzv5ljrt0sngjjnn25s4jzsu7qtts5d74cq8tz5

Project Overview 📄

We are intergrating AssemblyScript into substrate smart contract which is similar to parity's ink. It involve buillding substrate contract runtime api, builtin modules, and development sdk. we name the language and sdk as Subscript.


Subscript is a smart contract language written in AssemblyScript for substrate based chain. We will provide essential substrate api and builtin tools to support contract development.

Similar to parity ink, Subscript is built on top of AssemblyScript and follow all AssemblyScript syntax. Subscript is more like a development kit with some builtin module and tools. As assemblyscript is easy to interact with TypeScript and JavaScript, Subscript is much more friendly for dapp developers.

Project Details

Subscript is designed as standard AssemblyScript with builtin contract api. First of all, Subscript libray will provide basic contract pallet runtime api access.

  • contract runtime envionment
  • contract memory management
  • state storage access, set and get value by key.
  • event data generation and storage

The Subscript library also add support for contract interaction utilties, including:

  • contract metadata generator
  • basic data structure: dynimic array, map, list,
  • user struct storage layout
  • account and balance interface
  • contract call abstraction
  • builtin utility fuctions

The package will provide contract template and intergation tool with substrate node.

There is no plan for EVM Pallet support.

Ecosystem Fit

Some of the function of Subscript are similar to LimeChain's work of AssemblyScript Runtime, but they are made for different scenario. LimeChain AssemblyScript Runtime focus on building substrate runtime with wasm compiled from AssemblyScript. It involves building all the substrate runtime environment entry with AssemblyScript and other basic library. Subscript aims to implement all the substrate smart contract low level interface with AssemblyScript. Subscript also add support for basic contract lib and project template for easy development. We may benefit previous work from LimeChain such as SCALEcodec, runtime entry implemention.

Team 👥

Team members

  • Symon Ho: Fullstack developer Leading consensus R&D and engineering in multichain system. Prior to that, developer of openstack project, engaged in performance tools and monitoring system for cloud platform.
  • Ice Min: 10+ years experience in c/c++ development, real time database products and digital currency transaction platform products expert. Developer of BitCoin and Ethereum wallet.

Team Website

Team's experience

We implemented the fruitchain consensus integrated with ethereum, and used pbft to provide finalization in blockchain system. Fruitchain mainnet launched in 2019 and privide 500+ TPS for transaction validation.

We alse engaged in smart contract tools interaged with vyper for contract audit and testing.

Team Code Repos

Development Roadmap 🔩

We only provide milestone1 here for contract runtime api implementation. Full milestones are list in the general grant repo


  • Total Estimated Duration: 2 month
  • Full-time equivalent (FTE): 2
  • Total Costs: 2 btc

Milestone 1 — Implement smart contract low level api

  • Estimated Duration: 2 month
  • FTE: 2
  • Costs: 2 btc

In this milestone, all the basic substrate contract runtime api will be implemented in AssemblyScript. This stage will deliver a AssemblyScript package which provide encapsulation of current substrate contract api. With the AS api, contracts can be compiled to wasm and deployed on substrate contract node. We may benefit from the reference implemention of parity Ink and provide similar api.

The AS package will cover the following substrate contract api:

0a.LicenseApache 2.0
0b.TestingThis milestone will have unit-test for all the following runtime api impemented. We will mock most of the contract runtime api to simulate host functions. Integration test will be delivered in next milestone.
0c.DocumentationWe will provide both inline documentation of all the sdk api and basic code example that show how developers use the api.
1.contract runtime environmentcontract builder and execution to initailize the contract code
2.core typesadd core component: AccountId, Balance, Hash, Block accesscontract low level storage read and write with key
3.object packing utiltyProvide user-defined data structure packing and unpacking method to storage access.
4.memory manipulationImplement memory make and getter, setter
5.contract event generationGenerate event from contract call
6.contract call methodProvide method for make contract call.
7.hash utilityMake digest of encoded input to generate hash image
8.SCALE codecBuiltin codec functions to serialize and deserialize input. We may directly use LimeChain as-scale-codec implementation.
9.example for demonstrationProvide ERC20 contract example to test on substrate node

Future Plans

After the Subscript presentation , we may make our effort to bring more tool for contract development.

A simulated contract sandbox similar to ganache is needed to debug and test contract.

We may add more intergated tool and IDE packge for contract developer.

Additional Information

We expect any developer who is interested in AssemblyScript smart contract join us and build efficient framework.