The Xmonad window manager is configured by editing its source code as well, and believe me, you don't have to know Haskell to do it. They pushed the DSL approach to a point where the main function reads like a configuration file, whose format can be learned just by looking at it.
this is not entirely true, xmonad's config file happens to be a haskell file, but I don't need to recompile the whole xmonad project if I want to change it, I just start xmonad again.
It does some tricks to do this (mainly the _main_ xmonad executable compiles a custom binary for you taking the xmonad.hs as input), but it's a different case.
If this experience has been improved, I might try xmonad again. I used it for 2.5 years but switched to i3 in 2013 after finding myself in cabal hell for the umpteenth time. Recompiling GHC to make my window manager work was not my idea of a good time.
I switched from xmonad to another window manager and eventually to i3 many years ago, and there's no way I'm going back.
Yes, you can do simple stuff in xmonad without knowing Haskell. But for more complicated stuff, you have to either copy and paste code that you don't understand, or ask someone who knows Haskell to write it for you. And there's no way you're going to be able to do troubleshoot non-obvious problems without either knowing Haskell or once again asking someone who knows Haskell to do it for you. That's way too much of a pain in the ass.
Configuring and troubleshooting i3 doesn't require knowing Haskell, is really simple, flexible enough for what I need, and any advanced functionality I want it to perform I can program in my own language of choice.
