Sandtracks

Today, we're introducing Melange 4.0, the latest version of our backend for the OCaml compiler that emits JavaScript.

Melange is now compatible with OCaml 5.2! In this release, Melange starts emitting more ES6 constructs, supports more JavaScript builtins, improves error handling, and makes using Dune virtual libraries fully supported. Read on for more details.

I recently shared a 2024 progress update about our work on Melange. In that message, I briefly wrote about "universal libraries" in Dune, the ability to write a shared OCaml / Melange codebase while varying specific module implementations, flags, preprocessing steps, etc. according to the compilation target.

I also promised to dive deeper into what "universal libraries" are all about, and the new use cases that they unlock in Dune. Keep reading for an in-depth look at the history behind this new feature rolling out in Dune 3.16.

Last year we saw the first major release of Melange. Over the course of 2023, what started as disjoint sets of tooling has gradually evolved into a cohesive development experience within the OCaml Platform.

But we're not done yet. In the next few paragraphs, I'll tell you everything we've shipped so far in the first 3 months of 2024.

We are excited to announce the release of Melange 3, the latest version of our backend for the OCaml compiler that emits JavaScript.

This new version comes packed with significant changes, improvements, and a few necessary removals to ensure a more streamlined and efficient experience for our users. This new version is both leaner and more robust. We focused on fixing crashes and removing obsolete functionality, improving the developer and troubleshooting experience, increasing OCaml compatibility and JavaScript FFI integration.

As October 2023 unfolds, we'd like to present what we're planning to work on during what remains of 2023. Built upon the invaluable feedback of our users and our vision for Melange, we are excited about what's next.

Today, the Melange team is excited to introduce Melange 2.0. This iteration brings an upgrade to the OCaml 5.1 type checker, along with increased compatibility with the OCaml Platform. Melange 2.0 unifies the compiler attributes and libraries under the Melange brand and it improves developer experience across the ecosystem. We're also publishing a few battle-tested libraries to OPAM.

We're quite happy with how far Melange has come -- I previously wrote about releasing Melange 1.0 and a retrospective on Q2 2023.

But we're not done yet: there's more in slate for the next quarter. I'll tell you what we're looking to achieve in Q3 2023.