Show evaluation step-by-step in GHCi
The ability see every evaluation step for executing a particular code in ghci is needed.
Earlier that could have done in HAT, or ghc-vis. But as of today, HAT doesn't compile even with stack. And, at least personally for me, neither ghc-vis could be installed.
I want to point out that the funcionality is **very** important for the language. Without that (i.e. as it is now) it is impossible for newcomers to see how a particular construction going to be evaluated, how much memory it going to take. Nowadays newcomers have to deal with memory issues post-mortem: an app takes all system memory, dies, then one build everything for profiling, and start playing a Battleship with the allocation graph; which going to be a hard game, unless you're experienced enough to not even allow that to happen most of the times.
However, if there was a way to execute functions in GHCI, looking the evaluation step-by-step, days of hard debugging would turn into a few hours of executing a couple of functions in ghci.