Tim Spence
Senior Software Engineer at ITV
England, United Kingdom
Summary
🤩
Rockstar🎓
Top SchoolTim Spence is a senior software engineer with 11 years' experience who transitioned from a mathematics background (Cambridge) into functional programming and systems work, specializing in Haskell, Scala and Rust. He has shipped production backend features at companies like ITV and Permutive while contributing non-trivially to prominent Typelevel open-source projects (fs2, cats-effect, cats) and http4s, improving stack safety, async runtimes and HTTP parsing. Known for deep type-driven thinking, he focuses on correctness and composability—implementing things like AndThen for stack-safety and adding transformer instances for typeclass ergonomics. Based in the UK, he blends academic rigor with pragmatic engineering to strengthen both library internals and application-level reliability. An understated detail: many of his open-source patches target subtle runtime and parsing edge cases that quietly prevent production failures.
12 years of coding experience
9 years of employment as a software developer
Master of Arts (M.A.), Mathematics, Master of Arts (M.A.), Mathematics at University of CambridgeMaster of Science (MSc), Computing Science, Master of Science (MSc), Computing Science at Imperial College London
Github Skills (27)
asynchronous10
parserator10
concurrent-programming10
parser10
lib10
cats-effect10
typeclass10
async10
testing10
http10
data-structure10
scala10
stream10
fs10
f10
Programming languages (16)
Github contributions (5)
typelevel/cats-effect
May 2019 - Oct 2022
The pure asynchronous runtime for Scala
Role in this project:
Backend Developer
Backend DeveloperContributions:59 reviews, 398 commits, 72 PRs in 3 years 5 months
Contributions summary:Tim's commits primarily involve the development of core syntax classes and supporting infrastructure for the `cats-effect` library, which focuses on concurrent and asynchronous programming in Scala. The contributions included creating new syntax classes for asynchronous and concurrent programming, moving constraints onto methods, and formatting package objects. The user's work also encompasses the inclusion of monad transformer instances for the `Clock` type class, expanding the library's support for various functional programming constructs.
asynchronousscalafptypeclasses
typelevel/cats
Aug 2020 - Nov 2022
Lightweight, modular, and extensible library for functional programming.
Role in this project:Back-end Developer
Back-end DeveloperContributions:26 reviews, 61 commits, 18 PRs in 2 years 3 months
Contributions summary:Tim primarily contributed to enhancing the `Ior`, `WriterT`, `IorT`, and `ContT` data structures within the `cats` library. Their work included implementing `Order` instances for these types, indicating a focus on improving the library's functional programming capabilities by adding ordering capabilities. The user's commits also introduced features like `callCC`, `resetT`, and `shiftT` to the `ContT` data structure, focusing on adding delimited continuation. Furthermore, the user added `StoreT` and `RepresentableStoreT` with more features.
functional-programming
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