In Dark, we label (either manually for stdlib, or automatically for other functions) whether they are pure or not. Pure functions (most of them) do not need the

In Dark, we label (either manually for stdlib, or automatically for other functions) whether they are pure or not. Pure functions (most of them) do not need their results stored in traces (Dark has an always-on-debugger that uses "traces" saved from real inputs). Making a (mostly) pure functional language enables so much!