ephemeron

Ah!—so frail are we—

So like the brief ephemeron that wheels

Its momentary round, we scarce can weep

Our own bereavements, ere we haste to share

The clay with those we mourn.

Beyond type safety, OCaml has several features that closely interact with the garbage collector. These include weak references, finalisers, ephemerons, and lazy values, whose semantics will have to be preserved with the new GC so as to not break programs that use those features.