There‘s even a handy overview with all operators: Operators reference — Elixir v1.16.2
LostKobrakai
cmo
I much prefer CompareChain over (Date|DateTime|Time|etc).compare. Would be nice to have in Kernel.
2
LostKobrakai
José also tweeted about adding checks around comparing structs to the typesystem additions coming in 1.17:
4
PragTob
it’s really cool and makes me happy to know that I may have contributed in a small way to this (even if it’s just re prioritizing it) - blog post is already updated highlighting it! Genuinely one of the best things about elixir: DevX is taken very seriously and often times even issues I just think about are fixed a release or 2 later. The team has a very good and firm understanding of what issues people experience and follow through with fixing them often.
0
sasajuric
Author of Elixir In Action
Another gotcha with module attributes is that each reference injects the value, which can increase disk & mem usage. For example:
defmodule Foo do
@x Enum.to_list(1..1_000_000)
def foo, do: @x
def bar, do: @x
end
Here we inject two identical large lists in the code, and the resulting file is 6 MB.
In contrast, the following code:
defmodule Foo do
def foo, do: x()
def bar, do: x()
defp x, do: unquote(Enum.to_list(1..1_000_000))
end
produces a 4 MB beam, because the list is injected into the compiled beam only once.
In addition, I consider the 2nd version more flexible, because the “constant” can be provided after the implementation, which I often find better than listing various constants at the top of the file.
It’s also worth mentioning that both versions produce constants, as in terms which are handled in a special way by the runtime. See here for details.
18
sodapopcan
Using module attributes in a 1-1 way that constants are used in other languages is possibly the most prevalent anti-pattern I come across that actually causes negative side-effects. Well, based on my very small sample size, at least 
While a lot of has been done to cut down on what is considered a compile time dependency, liberally referencing other modules in attributes was a major source of long compile times at a previous job.
2
PragTob
Wow, I wouldn’t have expected that! Thanks for sharing. It makes sense when you think about how its probably resolved at the erlang level (i.e. since they may change, just insert their current value and not have it be a reference) but that’s surprising for sure! Thanks Saša!
0
sodapopcan
Oh, and another gotcha! Even after understanding comparisons, people (like past me) still forget that true, false, and nil are just atoms so comparing them is done so alphabetically.
3
BartOtten
Could you provide an example of a use case with such comparison? I just never seem to have never bumped into this one.
0
sodapopcan
I meant to say that it’s not really something you run into often, if ever. I honestly don’t remember the context in which it came up and it was actually a coworker who brought it. I was then confused myself until it hit me. It’s really just a point of potential interest.
0