Well, there has always been some very bare-bones debugging support in ghci (you can set breakpoints, step and inspect variables), but only for interpreted code, and zero debug adapter protocol integration or such things https://downloads.haskell.org/ghc/latest/docs/users_guide/gh... I've never managed to get any use out of it.

This new `hdb` however looks like the real thing. I like that they added a `DebugView` class for debug-specific pretty-printing. Even has a nice web page :) https://well-typed.github.io/haskell-debugger/