If you plan on writing your OS in Haskell in the usual sense (i.e. your OS executes pure Haskell functions and interprets some sort of IO monad) you're going to

If you plan on writing your OS in Haskell in the usual sense (i.e. your OS executes pure Haskell functions and interprets some sort of IO monad) you're going to end up implementing a full microkernel in another language just to get started. Not to mention it'll be a microkernel with a GC. The only way I could see a kernel being truly written in Haskell is in a DSL something like atom[1]. Atom is an EDSL represents code that not only doesn't need a garbage collector, but also has a verified constant bound on memory usage. However if that's what you're looking for, you might as well go with an EDSL in a dependently typed language like Idris to make verification easier and extensible. [1]: https://hackage.haskell.org/package/atom https://hackage.haskell.org/package/atom