There is a kind of magic to those systems that is worth experiencing. But it’s also worth examining why we prefer to build puppets.

Because I’ve had days where I’ve had to debug my surly emacs boy, and I’ve quickly discovered that his behaviour has very little to do with the code that I’m reading. Methods overridden at runtime, traces that end with a call to a closure that no longer exists, event handlers whose execution order depends on side-effects during module loading, stack-traces which contain multiple different versions of the same function. On the worst days I find myself debugging code that doesn’t even exist on disk but was evaluated in the repl weeks before.

source: L