JuliaCon 2025

Keno Fischer

Keno Fischer is one of the core developers of the Julia programming language and co-founder and CTO at JuliaHub. His earliest involvement with the Julia project was the port of Julia to Windows, the creation of (the current iteration of) the Julia REPL, the Julia optimizer, Julia’s --bug-report feature as well as numerous other language features and packages. Within the Julia community, he is known for creating packages that push the boundary of possibilities of the language and ability to debug even the thorniest of issues. He holds an A.M. degree in Physics from Harvard University.


Session

07-25
11:30
30min
Constants are no longer constant - what's up with that?
Keno Fischer

Julia 1.12 introduced significant changes to the semantics of global bindings and world ages. In particular, constant redefinition is now permitted in all cases (and the cases previously allowed are no longer considered undefined behavior). As an immediate consequence, struct redefinition is now possible, resolving the biggest remaining case in which Revise.jl was unable to hot-reload changed code. This talk will provide an overview of the new semantics, including common pitfalls.

General
Main Room 1 (Main stage)