Let Signals in OCaml

Signals and fine-grained reactivity are two popular concepts in the JavaScript world, thanks to their simplicity, ergonomics and excellent performance.

What are signals? What is their type? How can we use them in OCaml?

Let's build a reactive UI library from scratch to find out! From simple callbacks, layers are added to support batching, resource cleanup and let syntax for composing effects. DOM interactions are implemented to allow predictable, minimal and efficient UI updates.

Finally, helix is revealed, a library based on the presented reactivity principles. I review some examples and discuss how helix is used to implement real-world applications at Hyper and Tarides.