Simon Hafner
Founder at family.cards
Berlin, Germany
Summary
🤩
Rockstar🎓
Top SchoolSimon Hafner is a founder and seasoned back-end engineer with 17 years of experience building compilers, language tooling, and production services from Berlin. He has strong functional programming expertise demonstrated at IOHK working on Plutus costing models and at Zalando across Haskell, PureScript and Scala services deployed to Kubernetes. An active open-source contributor, Simon has helped shape language ecosystems—contributing to GHC proposals, the PureScript package-sets, Nim core utilities, and the widely used http4s Scala library. He combines low-level systems work (file I/O, hashing, memory accounting) with high-level language design and developer tooling. As a founder of family.cards since 2022, he pairs technical depth with product-minded execution. His academic background in computational linguistics hints at a long-standing interest in the intersection of language, compilers, and practical software engineering.
17 years of coding experience
4 years of employment as a software developer
Master of Arts (M.A.), Computational Linguistics, Master of Arts (M.A.), Computational Linguistics at The University of Texas at Austin
English, German
Stackoverflow
21,570reputation
1.4mreached
412answers
176questions
ruby-on-rails
top-5%
apache-spark
top-5%
scala
top-5%
csv
top-5%
ascii
top-5%
ruby
top-1%
Github Skills (43)
nim-lang10
programming-language10
benchmark10
package-management10
purescript10
http10
dhall10
benchmarking10
scala10
ruby10
lang10
compiler-compiler10
template-haskell10
fileio10
blockchain10
Programming languages (30)
Github contributions (5)
IntersectMBO/plutus
Nov 2019 - Oct 2020
The Plutus language implementation and tools
Role in this project:
Back-end Developer
Back-end DeveloperContributions:24 reviews, 21 commits, 28 PRs in 11 months
Contributions summary:Simon contributed significantly to the `plutus` repository, focusing on the implementation of costing functions and integration of benchmarking tools. They added costing models for various built-in functions, including integer and bytestring operations, and integrated these models with the existing evaluation mechanisms. The user also updated the codebase to incorporate ExMemory calculations, thereby refining the resource accounting of Plutus Core execution.
programming-languageblockchainsmart-contractsplutus
nim-lang/Nim
Mar 2011 - Mar 2016
Nim is a statically typed compiled systems programming language. It combines successful concepts from mature languages like Python, Ada and Modula. Its design focuses on efficiency, expressiveness, and elegance (in that order of priority).
Role in this project:Back-end Developer
Back-end DeveloperContributions:238 commits, 81 PRs, 63 pushes in 5 years
Contributions summary:Simon primarily focused on implementing and refining core functionality within the Nim programming language repository. Their work involved adding a new `readAll` procedure, addressing file input/output operations, and correcting related issues. The user also implemented additional utility functions such as random number generation and `hash()` for floats, alongside associated tests. Their contributions spanned several core system files and involved direct interaction with low-level system I/O.
pythonnim-langelegancecompilerprogramming-language
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