Solving the expression problem using Modern Java by Richard Warburton, Raoul-gabriel Urma

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Express yourself: solving the expression problem using Modern Java
Can you believe it is Java 17 already? Another small update? Not this time, Java 9 to Java 17 has brought significant changes in how we can now write day to day Java code. Introducing, Functional Programming 2.0. In this talk, we will cover the notorious expression problem and how it can be addressed using Java’s most modern language features including switch expression, sealed classes and pattern matching. We will incrementally refactor a code written pre-Java 9, using new features and approaches whilst showing the resulting code benefits including cohesion, decoupling and readability.

[@acronis536]

TDD could help in cases with less compile time checking i think

[@TJ-hs1qm]

"The Expression Problem is a concept in programming language design that highlights the challenge of extending a software system in two dimensions: adding new types and adding new operations over these types. The goal is to achieve extensibility without modifying existing code and while maintaining static type safety."
en.wikipedia.org/wiki/Expression_problem
The person at 41:32 is exactly right. Sounds like the presenters themselves didn't fully understand the Expression Problem. All they did is shift it around from OO style to FP style without solving anything.