On: Carp – A statically typed Lisp, without a GC, for ...

[cmrdporcupine]

Nah, only copying / generational collectors do heap compactification. A simple Mark&Sweep collector doesn't, for example. Nor does reference counting. Both of which are used by many Lisp or Lisp-like languages.

Nothing can substitute for a really good allocator.

[andi999 → cmrdporcupine]

So what happens to long running lisp programs? Running out of memory due to fragmentation eventually?

[xxs → andi999]

One would expect at least a provision for a stop the world phase. where all mutator threads get to wait for a massive defragmentation.