“Write at Index” node

It would be useful to have a “Write at Index” node in Geometry Nodes. The node would evaluate the field at the current element, but write the result to a different index given as an input.

This would allow random-access writing instead of only writing to the current index, which is currently hard to do with workarounds.

The current Evaluate at Index lets us read from arbitrary indices, but we cannot write to arbitrary indices. A ‘Write at Index’ concept would allow random-access writing, enabling buffer-like data structures, graph propagation, and custom simulations. Maybe this may conflicts with the pure field design, so I’m curious whether something like this could ever fit in Geometry Nodes.