Implement Enum.equal?

[meh]

It compares different kinds of collections based on the elements it would iterate through.

In my case, it would be useful to compare ets tables of ordered set type, it would also be used as fallback in Dict.equal? which I'm going to implement now.

[josevalim]

👍 We just need to discuss the naming. Dict.equal? should return true regardless of the order in the items. Enum can't and shouldn't do the same. So I am not sure if we should call it something else (what does clojure call it?) or keep it equal?.

[josevalim]

Oh, the build failed. Could you please check?

[meh]

Yeah, checking, I ran the tests and it was all green here.

[meh]

Oh, I completely forgot about doctests, I have no idea about how it works, any hints?

[yrashk]

may be it would make sense to add Enum.equal?(1 .. 3, [1 .. 3]) as well?

[meh]

Just in the examples? It should return false, shouldn't it?

[yrashk]

I meant 1..3, [1,2,3] this way it'll compare if both enums are equal as enums.

[meh]

Oh, sure thing, fixing it.

[meh]

Yeah, doctests are magic, I forgot to add a case with empty list and non empty iterator and luckily I put it in the examples.

[meh]

So I am not sure if we should call it something else (what does clojure call it?) or keep it equal?.

user=> (= { :a 2 :b 3 } { :b 3 :a 2 })
true

I guess Dict.equal? would be fine.

[josevalim]

Yes, Dict.equal? will be fine. My worries are about Enum.equal?. The
question is: should we make a difference between semantic equality (as in
Dict.equal?) and structural equality (as in Enum.equal?). If so, what
should we call the latter?

José Valim
www.plataformatec.com.br
Founder and Lead Developer
*

[meh]

user=> (= [1 2 3] '(1 2 3))
true

Clojure doesn't care.

[ericmj]

@josevalim Do you mean difference in ordering of elements? Or difference in structure? (i think both Enum.equal? and Dict.equal? should ignore structure)

[josevalim]

Yes, structural was not the best choice of word. I should have said
semantic or not, Enum is not structural. :)

Let me give another example: today we have Keyword.equal? that works only
for keywords. Would we want something like this too? The same as
Dict.equal? but also asserting on the type?

Another example of semantical behavior: String.equal?. We could have a
version that checks if two Unicode strings are the same, since a string
like "josé" can be represented in two different ways.

Note we already have a strict equal impl, via ==. :)

José Valim
www.plataformatec.com.br
Founder and Lead Developer
*

[meh]

So like an Enum.equal?/3 with a first "type" check?

[meh]

Wait on merging this if the naming issue is resolved, I'm adding a version where you can provide a function to compare the elements.