Johannes Waldmann FbIMN wrote:

How can I get more information if my ghc-compiled program halts with "<<loop>>"

There isn't a way to get more information right now. But <<loop>> is an exception (NonTermination), so you can catch it.

What kinds of cyclic dependencies does the runtime system actually recognize?

The kind where a value depends on itself, also known as a blackhole. Cheers, Simon