> Languages that support it via square brackets: Rust, Ruby, Javascript,
> Python, C, Julia.
All of these languages (other than maybe Julia? I have not used it at all.) are
actually using arrays and not lists. It is fairly natural to have easy index
based lookup for arrays. After all, it is
On 21/09/2023 20:19, 'Justin Wood' via elixir-lang-core wrote:
Depending on what exactly you are doing, and the size of your lists,
it may be worth taking a look at the :array module provided by Erlang.
It will give you logarithmic access times, or O(log n). But it still
has the downside of
Nice . That is a definite improvement. Ultimately, I think it would be a nice
improvement to the language, but I don't disagree with the idea that we need to
take great care for the on ramp and to help people avoid footguns. I don't
think its very likely that I'll convince the team to add it,
For what is worth, the error message on main says:
---
iex(1)> [1, 2, 3][0]
** (ArgumentError) the Access module does not support accessing lists by
index, got: 0
Accessing a list by index is typically discouraged in Elixir, instead we
prefer to use the Enum module to manipulate lists as a
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 (
Yeah, I'm familiar with the differences on that front, but at the end of the
day there are plenty of times where its perfectly normal to get a list/tuple
element by index. It seems like a natural syntax extension to me (the syntax is
basically already there, just intentionally blocked off in a
I mean ` Enum.at/2` ( http://enum.at/2` )
On Thu, Sep 21, 2023 at 1:14 PM, Zach Daniel < 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
Right now if you use access on a list, it expects it to be a keyword and
requires the value to be an atom.
I've tried to think of a reason why we couldn't support this in the
language, but I haven't been able to. If the value being accessed is an
`integer` it could get the item at that index,
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
Index-based access on a list is very frequently an anti-pattern. Allowing
list[i] means it will be easier to write non-efficient versions of
algorithms without a second thought for those coming from imperative
languages, instead of using the functions in Enum. It means someone can
write this:
for
> 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
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