[Haskell-cafe] Basic list exercise

[MigMit]

If I understand correcly, Data.List is building a lot of closures — basically, a CPS transform. I though about it, but I'm not sure it is better.

> On 24 Mar 2023, at 18:44, Johannes Waldmann <johannes.waldmann at htwk-leipzig.de> wrote:
> 
> > can we do better than this?
> 
> Does the implementation in Data.List do better?
> 
> https://hackage.haskell.org/package/base-4.18.0.0/docs/src/Data.OldList.html#sort
> 
> note that 'ascending' does some trickery there -
> perhaps exactly to solve the problem you describe?
> 
> Since this is about "exercise" - I would expect my students
> to find that code, so perhaps I'd point them to it right away,
> and give the task to "understand it" (= argue that it is correct).
> Arguing about cost seems harder.
> 
> 
> NB: 'descending' is different here, and that's no surprise
> since lists are asymmetric. We do have a symmetric (and strict) implementation of sequences - how do we sort these?
> 
> https://hackage.haskell.org/package/containers-0.6.7/docs/src/Data.Sequence.Internal.Sorting.html#sortBy
> 
> That's not exactly an advertisement for functional programming,
> as it has "state" written all over the place?
> But it makes for a nice exercise reading the types.
> 
> I needed some time to understand that the mouse-over block
> for an identifier contains _two_ types:
> the instantiated one (for the use site)
> and, below that, the general one (from the definition).
> 
> 
> - J.W.
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