[enhancement] receive predicates based on receive data

[grebe]

What's hard to do? (limit 100 words)

There are some cases where you want to perform a receive based on some element of the received data, for example AXI thread id. You can work around this with extra state to hold values you aren't ready to deal with, but that adds area and performs a receive you might not want to do for other reasons.

Codegen'ing these could be annoying because it increases the possibility of cycles.

Current best alternative workaround (limit 100 words)

Extra state.

Your view of the "best case XLS enhancement" (limit 100 words)

Perhaps a form of receive that accepts a lambda T -> bool