VM-Coder: Pallets to Contracts, Unlocked & Untamed | Sub0 2025
•December 5, 2025
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Why It Matters
EVM Coder dramatically reduces the complexity and risk of building Solidity‑compatible pre‑compiles on Substrate, enabling faster, more reliable deployment of advanced blockchain features and broadening the developer base across ecosystems.
Summary
The talk, delivered by Maria Matsushina, Director of Engineering at Unique Labs, introduced “EVM Coder” (formerly VM Coder), an open‑source library that bridges Solidity contracts with Substrate‑based parachains. Matsushina framed the problem as a clash between two worlds: the EVM’s ABI‑driven contract model and Substrate’s WASM runtime, which together make writing pre‑compiles labor‑intensive and error‑prone. By showcasing Unique’s experience as one of the first EVM‑compatible parachains, she positioned the tool as a template for other chains seeking true Web3 programmability.
Key insights centered on the pain points of manual ABI encoding. Developers traditionally wrote hundreds of lines of Rust to calculate offsets, handle dynamic arrays, and hash event signatures—code that was difficult to test, debug, and maintain. EVM Coder automates these steps: it validates selector expectations at compile time, generates Solidity interfaces from Rust annotations, and derives ABI‑compatible structs with a single attribute. The library also supports advanced features such as function overloading, deprecation flags, and automatic documentation sync, eliminating the “magic numbers” and hand‑rolled byte manipulation that previously plagued pre‑compile development.
Matsushina illustrated the impact with a concrete example: a dynamic NFT from the Wood Universe project whose properties are represented by nested dynamic strings and byte arrays. Using the traditional approach, the pre‑compile required extensive manual offset calculations; with EVM Coder, the same logic collapsed into clean, readable code without manual byte handling. She highlighted the “derive ABI Coder” macro that encodes and decodes custom structs automatically, and noted that Rust comments are translated into Solidity docs, ensuring a single source of truth for both languages.
The implications are significant for the broader Substrate ecosystem. By lowering the technical barrier to expose complex pallets—such as advanced NFT, fungible token, and transaction‑sponsoring modules—to Solidity developers, EVM Coder accelerates the creation of interoperable dApps and expands the developer pool. Chains that adopt the library can deliver higher performance and safety from Substrate while leveraging the mature tooling and ecosystem of Ethereum, positioning themselves competitively in the race for cross‑chain Web3 adoption.
Original Description
Maria Matyushina - Director of Engineering at Unique Network.
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