Oleg Grenrus
Haskell Consultant at Well-Typed LLP
Pori, Satakunta, Finland
Summary
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Rockstar🎓
Top SchoolOleg Grenrus is a Haskell consultant with 17 years of professional software experience, based in Pori, Finland, currently at Well-Typed LLP. He has deep backend expertise in Haskell and compiler/tooling internals, contributing to prominent projects like GHC, Aeson, Servant, Cabal, and the Haskell Tool Stack. His open-source work spans libraries for containers, parsing, JSON, testing and FRP, showing a knack for type-class design, build/CI improvements and cross-package compatibility. Prior roles include full-stack and mobile work at Futurice and academic teaching at Aalto University, reflecting both applied engineering and mentoring experience. Notably, he has made low-level contributions to compiler generics and diagnostics, indicating a strong grasp of language design as well as practical API maintenance.
17 years of coding experience
13 years of employment as a software developer
Master's degree, Electrical Engineering, Master's degree, Electrical Engineering at Aalto University
Russian, Finnish, English
Stackoverflow
12,067reputation
496kreached
206answers
18questions
scala
top-5%
logic
top-5%
haskell
top-5%
Github Skills (94)
dependency-management10
agda10
package-management10
parser-combinators10
testing10
language-design10
template-haskell10
build-automation10
backend10
haskell10
javascript10
typeclass10
purescript10
clojure10
hackage10
Programming languages (28)
Github contributions (5)
jsverify/jsverify
Sep 2013 - Apr 2021
Write powerful and concise tests. Property-based testing for JavaScript. Like QuickCheck.
Role in this project:
Back-end Developer & Test Automation Engineer
Back-end Developer & Test Automation EngineerContributions:8 releases, 536 commits, 121 PRs in 7 years 7 months
Contributions summary:Oleg contributed to the development of a pair generator and introduced support for a sum data structure. They also contributed to implementing the testing suite by fixing async issues, added new test cases for several primitive generators. The user has modified the test structure to include assertions. The code changes indicate contributions toward the core property based testing framework and its testing.
property-based-testingavajsdomtestingjavascript
haskell/parsec
Sep 2015 - Jan 2023
A monadic parser combinator library
Role in this project:Backend Developer
Backend DeveloperContributions:8 reviews, 35 commits, 53 PRs in 7 years 4 months
Contributions summary:Oleg primarily focused on maintaining and updating the Parsec library, a monadic parser combinator library written in Haskell. Their contributions included bumping upper bounds for dependencies like HUnit and semigroups, fixing compatibility issues, and adding new features. Furthermore, the user integrated GitHub Actions for the project's CI/CD pipeline, improved the build process, and added new test cases. They also introduced and improved some parsing functions and fixed the code style.
monadicparser-combinatorcombinatorparser
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