Is this stealth promotion for Go?
Although I have been considering using it for production, it's not what I need in a prototyping language at all.
There's also scripted go, which may solve some of what you need.
Print debugging works for 99% of introspection needs. Most times go does just as advertised, though learn of common pitfalls to avoid.
Haskell has REPL and dynamic introspection, but everything takes 4-20 longer times. Maybe it's faster/better with massive practice.
Honestly, most codebases just sucks, including my own, unless you redo alot and put deliberate efforts over time. Which is irrelevant to sales (point in link). Alot of value in battle-tested code turns invisible too, locking knowledge away in obscurity. Go at least is pretty readable and mostly explicit.
That said, gdb is probably in the same space as git is: hard to fully use, but the best in its own space.
With Haskell being a tough nut, maybe it could help though. So may as well try it.
I found git trivial to start using immediately, and almost possible to understand from first principles (ie. almost like versioned subdirs improved). It's a bit more involved, but with right online content, one starts to catch on (leaving magical thinking).