Comment by mattparas

Immutable values are reference counted, so for most code, things will be dropped when they exit scope. For captured mutable values, there is a fairly mundane mark and sweep collector. It is possible to manually control the garbage collector, however I have not optimized it for that kind of workload. If you were embedding Steel in a game, I don't think it would be explicitly necessary to tune the GC as long as you aren't using a ton of mutation. If you were using a lot of mutation and still wanted a relatively performant GC collection at the end of every frame, then the underlying GC implementation would have to be changed or swapped to a different one (which is not impossible - I just only have one GC implemented)