Since joining Epic Games in late 2021, I have been involved in the design and development of Verse, a new, declarative programming language that Epic plans to use as the language of themetaverse.

Verse is extremely ambitious: we want it to allow millions of programmers who have never met towrite code that inter-operates to build a shared virtual 3D simulation in which billions of users can interact. My current focus is on formally specifying the technical heart of Verse. At its core, Verse is a functional logic language, up to now rather a niche subject. In the talk I will give you a sense of what a functional logic language is; I will describe the challenges with giving it a formal definition; and I will sketch our progress in addressing this challenge using denotational semantics, rewrite rules, and a reference interpreter.