If you haven't upgraded or downloaded the newest version of Unison, M4d, it contains several quality of life improvements for users, including but not limited to a beloved feature for frustrated developers: stack traces.
How to invoke stack traces
A stack trace will be generated upon calls to Exception.raise and when base.bug has been called. It contains the names of the functions that have been called en-route to generating the failure, with the last term being the entry point to the program.
Check it out in action
A technical detail worth bearing in mind is that Unison supports tail-call elimination, so functions that are in tail call position are evaluated without growing the function call stack. These functions won't show up in the stack-trace.
We hope stack traces will help when you're stuck. Better yet, channel your inner Unison teammate, Cody, when he says: "I don't write bugs so I've never seen a stack trace." 😂