You don't need to anything about the compiler internals to know that a String is a linked list, and that concatenating a linked list is expensive, and that ShowS is a function interface that enables optimized contatenation.

Rope is a data structure, not a function.

https://hackage.haskell.org/package/base-4.19.1.0/docs/GHC-S...

https://hackage.haskell.org/package/base-4.19.1.0/docs/Data-...