Hi, asterius main dev here. Garbage collection support is near; we're working actively on it, and after a few regressions are fixed it'll be available on master.

It'll be a copying GC, with builtin support to automatically free unused JavaScript references in the Haskell heap. It's also possible to plug in more fancy gc algorithms later (e.g. generational, or concurrent ones with read barriers).

To be clear, this will be your own GC bundled with each application, not an interface to the host browser's GC?

Indeed it's not an interface to the browser's gc.

There does exist a wasm anyref proposal which enables manipulating opaque references in wasm and a gc proposal for further allocating/using such garbage collected objects. However, basing our gc on those is currently less pragmatic than rolling our own :)