Sjoerd Visscher
Senior Software Engineer at Input Output (IOHK)
North Brabant, Netherlands
Summary
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Rockstar🎓
Top SchoolSjoerd Visscher is a senior software engineer with 17 years of professional experience and a web development career stretching back to 1996, now blending deep Haskell expertise (since 2008) and category-theoretic thinking (since 2019) into blockchain and language tooling. Based in North Brabant, Netherlands, he has contributed to high-profile open-source projects including GHC and Cardano core components, focusing on compiler tooling, API refinement, and smart-contract infrastructure like Plutus. His work reveals a knack for improving build and documentation processes, fixing subtle encoding issues, and evolving core language abstractions such as Foldable/Traversable and token handling. Currently on IOHK’s DJED team after several years at Tweag and prior roles spanning R&D and product engineering, he combines low-level language design skills with practical backend development. An interesting detail: he runs a long-standing personal company (w3future.com) and brings a rare mix of decades-long web experience and formal-functional programming fluency to complex distributed systems.
17 years of coding experience
20 years of employment as a software developer
Applied Mathematics, Applied Mathematics at University of TwenteFlorens Radewijn College
Dutch, English
Stackoverflow
11,920reputation
474kreached
117answers
3questions
meteor
top-5%
monads
top-5%
functor
top-5%
functional-programming
top-5%
internet-explorer
top-5%
logic
top-5%
Github Skills (26)
programming-language10
compiler-design10
haddock10
blockchain10
smart-contracts10
haskell10
functor9
apidoc9
build-system9
meteor9
api9
functional-programming9
logic9
internet-explorer9
monads9
Programming languages (19)
Github contributions (5)
IntersectMBO/plutus
Mar 2021 - Jun 2022
The Plutus language implementation and tools
Role in this project:
Back-end Developer
Back-end DeveloperContributions:80 reviews, 59 commits, 65 PRs in 1 year 3 months
Contributions summary:Sjoerd made significant contributions to the Plutus language implementation and tools, focusing on the `plutus` repository. The commits show code modifications related to the PlutusTx Prelude, including improvements to fixities and the addition of the Foldable and Traversable classes, indicating a focus on core language features. Further commits involved the refinement of token name handling and adjustments to parameterised script instances, which align with the repository's focus on blockchain and smart contract development.
programming-languageblockchainsmart-contractsplutus
IntersectMBO/cardano-node
Jun 2021 - Sep 2022
The core component that is used to participate in a Cardano decentralised blockchain.
Role in this project:Back-end Developer
Back-end DeveloperContributions:6 commits, 6 PRs, 5 comments in 1 year 3 months
Contributions summary:Sjoerd primarily focuses on enhancing the Cardano API within the `cardano-node` repository. Their commits center around refining and expanding the API's functionality by completing patterns and exporting new elements. This includes adjustments to `TxBody`, `Tx`, and the export of `PlutusScriptV1` and `TxBodyScriptData`. Additionally, the user addresses potential issues with character encoding of asset names.
core-componentblockchainplutusdecentralisedcardano
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