Ryan Lemmer

Cape Town, Western Cape, South Africa

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Summary

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Rockstar

🎓

Top School

Ryan Lemmer is a seasoned software maker, coach and strategy consultant with 17 years of professional experience and a 25-year history of building and guiding engineering teams across startups and established companies. He blends hands-on backend development and Haskell expertise—having contributed to notable Cardano repositories such as cardano-sl and cardano-ledger—with product-minded architecture, technical coaching, and organisational design. As former CTO of NFTfi and Senior Haskell Developer at IOHK, he specialises in translating between technical and business stakeholders, assessing cross-impact of product and technical decisions, and rescuing complex projects. Based in Cape Town, he combines deep cryptographic and blockchain interest with a pragmatic belief in decentralised technologies’ societal potential. A former master’s student in Mathematics and Computer Science, he often pairs rigorous formal thinking with practical engineering to simplify risky projects and improve developer workflows.

17 years of coding experience

8 years of employment as a software developer

Master's degree Mathematics and Computer Science, Master's degree Mathematics and Computer Science at Durban University of Technology

Github Skills (9)

cryptocurrency10

data-structures10

ledger10

back-end-development10

haskell10

data-structure10

blockchain10

implement10

algorithms9

Programming languages (1)

Haskell

Github contributions (5)

IntersectMBO/cardano-ledger

Apr 2019 - Jan 2021

The ledger implementation and specifications of the Cardano blockchain.

Role in this project:

Back-end Developer

Contributions:64 reviews, 192 commits, 150 PRs in 1 year 9 months

Contributions summary:Ryan primarily focused on implementing and improving the ledger implementation for the Cardano blockchain, adding size costs for various block components and removing a custom `HasTypeReps` instance to add missing costs. The user addressed missing imports and refactored existing code to simplify and expand properties related to abstract size. The user also removed deprecated code and refactored existing code, and made changes related to the Epoch and BHEAD STS.

adablockchainplutuscryptocurrencyspecifications

input-output-hk/cardano-sl

Mar 2018 - Nov 2018

Cryptographic currency implementing Ouroboros PoS protocol

Role in this project:

Back-end Developer

Contributions:45 commits, 19 PRs, 82 pushes in 7 months

Contributions summary:Ryan primarily contributed to the backend logic of the Cardano SL project, specifically focusing on the wallet implementation. Their work involved creating a pure data layer for passive wallets, which included implementing various features related to wallet state management, UTxO handling, and pending transaction processing. Furthermore, they addressed warnings, added tests, and fixed bugs related to balance calculations and block metadata, indicating a focus on improving the wallet's core functionality. The user also worked on integrating a persistent state using AcidState.

cardanocryptographyposadacryptographic

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