London Scala User Group

🗣️ Katrina Petrevice: Caching in Scala using Ref
Caching in memory is often one of the first strategies used to improve system performances. However, implementing caching in a purely functional way introduces unique challenges, specifically around state management and testability. In this talk, we will look at how to utilise functional programming principles with Ref, while maintaining clarity and composability. We will also deep dive into some common pitfalls and look into practical ways to test Ref effectively.

⭐ Katrina Petrevice ⭐
Katrina comes from a non–computer science background and was first introduced to Scala while working at JPMorgan. She credits much of her Scala knowledge to hands-on experience within her team, where she works on building and maintaining data pipelines and managing data systems. Since then, she has developed a strong interest in functional programming and now co-leads the Functional Programming Group at JPMorgan, where she helps share knowledge and foster a community around these ideas.

🗣️ Caroline Morton: Accidental Functional Programming in Rust (From an Epidemiologist's Perspective)
I don't have a background in functional programming - and I never set out to write it. But somewhere between writing trait-based epidemiological pipelines, composing data transformations, and leaning hard on Result, enums, and pattern matching, I started hearing from others: “That's pretty functional.”

In this talk, I'll explore what it means to write “functional-ish” Rust as someone solving real-world scientific problems. I'll walk through the patterns I reach for - like chaining iterators, avoiding shared state, and embracing expressive types - and reflect on which functional programming ideas emerge naturally in Rust, even if you're not trying.
I'll also share how designing for epidemiologists - most of whom are used to chaining functions in Python (like Pandas) or R - has pushed me toward creating ergonomic Rust APIs with Python and R bindings. These tools aim to feel familiar to scientists while leveraging Rust's power and safety under the hood.

This is a talk for functional programmers curious about Rust, and for Rustaceans wondering if they've been functional all along. No formal theory required - just real code, real use cases, and a pragmatic perspective from someone building public health tools in Rust.

⭐ Caroline Morton ⭐
Dr. Caroline Morton is a medical doctor, epidemiologist, software engineer, and PhD candidate specialising in synthetic data, epidemiology, and Rust. With 60 peer-reviewed papers and two books on software, she combines deep technical expertise with a commitment to improving scientific workflows.

Caroline co-founded the first Women in Rust group, fostering diversity and encouraging more women to explore opportunities in systems programming. She leads an open-source project improving codelist management in epidemiology using Rust, creating efficient, reliable tools for health data research.
Her PhD focuses on synthetic data methods for epidemiology, particularly using Rust to generate large, realistic datasets. A strong advocate for open science and reproducibility, she contributes extensively to improving software practices through publications, workshops, and open-source projects.
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