[agentultra]

I wonder if there could be a (or already is) a "teaching" Prelude designed for this purpose.

One of the reasons the standard Prelude includes partial functions and specialize versions of `map` and `filter` is to support the pedagogical use-case (as far as I understand the situation). Most production applications will use a custom Prelude of some kind in order to prevent programmers from using foot-guns like `head` or make things more general in the case of `map` and `filter`.

Turns out using linked-lists for everything isn't the best idea but a lot of Haskell applications will use them because it's in Prelude.

Bit of a balancing act supporting both use cases.

[jerf]

I don't know if there is one already, because the Haskell community generally heads in the other direction with its alternate Preludes.

But the effort to fix up the fixable issues mentioned in the post is about the same as writing the post was. Getting it distributed to the students may be a bit harder, depending on the local setup.

But it's definitely fixable with Haskell as it is today.

Linked lists are particularly tricky in Haskell, because as a data structure manifested in memory, they really stink. But as a lazy data structure traversed exactly once and thus just serving as a mechanism for providing "the next thunk", they're fine. Haskell and its laziness completely conflates the two of these, so it ends up being easy to think you have one and end up with the other.

[agentultra]

Definitely. Linked lists are great for pedagogy and useful in many applications. I think it’s a bit of a sign that the struggle between pedagogy and practice can lead to suboptimal outcomes for both parties.