Robert Smart: Functional types in a property-based hierarchy

​Melbourne Compose is the monthly in-person meetup for functional programmers in Melbourne, every 3rd Thursday of the month in Carlton.

Our September session will be held 5:30-8pm Sept 18th at our regular venue, Activity Room 2 at Kathleen Syme Center in Carlton. Arrive from 5:30 for chat and socialising, talks start around 6:30.

Robert Smart will be presenting this month:

Functional types in a property-based hierarchy

Sets of things in real life and in mathematics are naturally organised into a hierarchy based on their properties. This is the correct way to handle a subtyping hierarchy in a functional programming language. A key ingredient is the use of properties whose types represent propositions. Extending this hierarchy to an (order) lattice makes types behave like sets, as sets are used in mathematics (and in the TLA+ program analysis system). This combination has many useful and interesting effects in type checking, operator definition, and program execution. From a programmer's point of view it makes static type checking behave more like run time type checking, which is typically easier to understand. The talk may head in various directions, depending on participant interactions.

This talk should be accessible for programmers from a variety of programming language backgrounds. You can get a preview of the topic at:

https://wombatlang.blogspot.com/2024/11/the-case-for-subtypes-real-world-and.html

As always, newcomers welcome. Reach Ben on 407 990094 if you have trouble accessing the venue.

Hope to see you there :)