Something else I would say: if we are doing this to protect people from writing non-idiomatic code, can we improve the error message for when you provide an integer to bracket access a list? Something like:
If you are trying to get an element from a list by index, use ` Enum.at ( http://enum.at/ ) ` instead. However, please read the warnings about working with lists from X guide… Or we could just include the explanation in-line. ` Enum.at ( http://enum.at/ ) ` should also potentially have a more clear warning for beginners directly in its docs. I would rather support the syntax, but if we're doing it to help people write idiomatic code (which will probably be mostly beginners), we should point them more clearly to this then IMO. On Thu, Sep 21, 2023 at 1:25 PM, Zach Daniel < zachary.s.dan...@gmail.com > wrote: > > I mean ` Enum. at/ 2` ( http://enum.at/2` ) 😆 > > > > > > > > On Thu, Sep 21, 2023 at 1:14 PM, Zach Daniel < zachary. s. daniel@ gmail. com > ( zachary.s.dan...@gmail.com ) > wrote: > >> Languages that support it via square brackets: Rust, Ruby, Javascript, >> Python, C, Julia. >> >> >> I see your point, ultimately for me what is frustrating is when I have >> predefined data structures and we have a tool for "get the value at some >> point (i.e map keys)" so I can do `map[:key][:key]` but if I want to write >> `map[:key][0][:key][0]` I have to reorient the code entirely to use >> `get_in` or piped functions like `|> Map.get(:key)`. Getting a key out of >> a keyword list would be equally as slow as getting a list at an index, so >> it didn't seem to me like the purpose of the `[]` was to only do fast >> operations. >> >> >> >> There are plenty of cases where I need to get things positionally out of >> lists, the two that come to mind are handling various data structures that >> I got externally, like from an API (I can use bracket access until I get >> to a list then I can't) and testing. Often I'm testing that something at a >> very specific point in a produced data structure is a specific value. I.e >> "the tenth item at the path `foo[:bar]` is X". I can do that with pattern >> matching, but its only feasible to a point (like pattern matching the 10th >> item from a list does not look good). We can use `get_in` but we could >> also make that argument for everything and not have bracket access at all. >> It seems like a natural extension of that choice to give lists (and >> probably tuples) sensible behavior with bracket syntax. >> >> >> >> I'm not necessarily convinced that not having `list[i]` will ultimately >> convince people not to write those bad algorithms, because they can just >> as easily say ` List. at ( http://list.at/ ) (list, 1)`. But wether or not >> I'm convinced of that is not relevant 😆 >> >> >> >> >> >> >> On Thu, Sep 21, 2023 at 12:39 PM, Justin Wood < me@ ankhers. dev ( >> m...@ankhers.dev ) > wrote: >> >>> >>> >>> >>>> It was pointed out that perhaps we don't do this to express that indexing >>>> a list is not fast in Elixir like it is in other languages, but I'm not >>>> sure if that is sufficient reason IMO to leave out a typically very >>>> standard feature of lists. >>>> >>>> >>>> >>>> Thoughts? >>>> >>>> >>> >>> >>> >>> Can you give an example of a language that supports this? In my >>> experience, languages do not provide this. >>> >>> >>> >>> In Haskell, you need to the non-standard !! operator. >>> >>> >>> >>> myList !! 5 >>> >>> >>> >>> OCaml does not provide a way to do this at all and you need to manually >>> iterate through the list to find the element you want (maybe other stdlibs >>> like Core provide something, but I have not used them) >>> >>> >>> >>> Racket has the list-ref function in order to accomplish this >>> >>> >>> >>> (list-ref my-list 3) >>> >>> >>> >>> Common Lisp has the nth function for this >>> >>> >>> >>> (nth 5 my-list) >>> >>> >>> >>> In comparison, Elixir has provided the Enum. at/ 2 ( http://enum.at/2 ) >>> function. >>> >>> >>> >>> >>> While I believe most languages do provide some facility to retrieve the >>> value at some index of a list, most do not provide it as square bracket >>> indexing you would see in other languages where arrays are more common >>> such as Ruby or Javascript. >>> >>> >>> >>> Justin >>> >>> >>> >>> >>> >>> -- >>> 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+unsubscribe@ googlegroups. com ( >>> elixir-lang-core+unsubscr...@googlegroups.com ). >>> To view this discussion on the web visit https:/ / groups. google. com/ d/ >>> msgid/ elixir-lang-core/ dc142043-83dc-48e6-8c3f-7a39c8376d0e%40app. >>> fastmail. >>> com ( >>> https://groups.google.com/d/msgid/elixir-lang-core/dc142043-83dc-48e6-8c3f-7a39c8376d0e%40app.fastmail.com?utm_medium=email&utm_source=footer >>> ). >>> >> >> > > -- You received this message because you are subscribed to the Google Groups "elixir-lang-core" group. 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