I believe there's actually a name for this pattern and it's "endofunctor": https://www.quora.com/What-is-an-endofunctor
ramda (and my own unction) adheres to this philosophy and it works very well. On Mon, Oct 16, 2023 at 12:23 AM Mihai Potra <m...@mpotra.com> wrote: > The *Enum module* currently in many of its defined functions (i.e. > *reject/2*) relies on lists and forces *Enumerable* implementations to > operate and returns lists. > > One example of this is the *Enum.reject/2* function that operates with > *Enumerable.reduce/3* but then it pipes everything into *:lists.reverse/1. > *This forces all *Enumerable* implementations to return lists so that > *Enum.reject/2* always returns a list. > > Ideally, *Enum* module would work with any *Enumerable* implementation > and its function return the Enumerable data type that the implementation > provides. Having Enum conform to operating with Enumerables this way would > allow less friction in working with enumerables and better support for > implementing Enumerable/Collectable concepts with structs and data types. > > As an example, removing a key or key-value from a map would be a simple > *Enum.reject* call instead of piping the map into the Enum.reject/2 and > then into a list to map conversion. > I've stumbled upon this while writing a library that would operate with > Source and Sinks as enumerables and collectables to allow for all sorts of > predefined types and custom defined structs, and got blocked at abstracting > away some of its core features. > > The good news is that finding a solutions might not be *that* complicated > and I'd be happy to make a PR for it *(already tried replacing > :lists.reverse/1 with a different function that respects the data type > returned by Enumerable.reduce/3)* > > *Challenges* > The biggest challenge here is obviously backwards compatibility with code > that relies on the Enum functions that return a list to keep returning a > list, so here's where I'd want a discussion and guidance on the best course > of action. As far as I can see, there's three options: > > *1.* Have a new module written out of `*Enum*` (say *Enum2*) and > deprecate Enum in the future - a better module name than just Enum2 is > definitely a must (looking for suggestions). *I suspect this would also > open the door to simplifying the Stream module.* > > *2.* Extend the *Enumerable* protocol to include a `reverse/1` function, > *and* a `new/1` function to replace the empty list constructor `[]` used > by Enum. Need to consider existing user code that implements Enumerable as > it would break without defining these two new functions. > > *3.* Create a new protocol that Enum would use, with fallback to current > behaviour. Best for supporting current user implementations of Enumerable > and keeping current behaviour, but doesn't make sense on the long term. > > Also as a last decision to be made is how to deal with Map. Ideally, Enum > functions would also return a Map if the enumerable is a map, but many rely > on the current behaviour of it returning lists because this has been the > status quo. This makes me favour option 1 of having a new module to replace > Enum in the future. > > Looking forward to hearing your thoughts and suggestions/proposals for how > to best take on this. > > Kind regards, > Mihai > > -- > You received this message because you are subscribed to the Google Groups > "elixir-lang-core" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to elixir-lang-core+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/elixir-lang-core/9d0f6096-43aa-441b-9060-1a4949ff8e67n%40googlegroups.com > <https://groups.google.com/d/msgid/elixir-lang-core/9d0f6096-43aa-441b-9060-1a4949ff8e67n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- Kurtis Rainbolt-Greene, Software Developer & Founder of Difference Engineers 202-643-2263 -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. To unsubscribe from this group and stop receiving emails from it, send an email to elixir-lang-core+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/elixir-lang-core/CAMhJPGh_gBiwvFn%3D%2B%2B_EZdPNvaPNJODohmXj2y1jH_ySdi_r6g%40mail.gmail.com.
