alisinabh

alisinabh

So in elixir sometimes you need to do something like this:

def function(acc, condition1, condition2) do
  acc <> 
   cond do
     condition1 -> "hello"
     condition2 -> "world!"
     true -> "" # Add nothing to acc
   end
end

Sometimes you need to use an empty string. Currently i only see two options for that

  1. using "" (empty string with two double qoutes)
  2. using <<>> (empty binary)

It would be a good thing if Elixir’s String module would provide a function like: String.empty/0 that would return a human readable form of empty string in Elixir.

But for now, Which way you think is better to use? 1 or 2? Or any other solutions?

I personally think that 2 is better since no special chars can hide inside it!

Showing Posts 1 to 10

OvermindDL1

OvermindDL1

Heh, now that Unicode is out in full force, that is not at all a bad point, hmm…

alisinabh

alisinabh OP

NobbZ

NobbZ

I’m not sure if we really need String.empty/0. Thats very noisy and writing the empty string literally saves me a lot of keystrokes.

And if one should use "" vs. <<>>, well it depends. If I am dealing with String (meaning a sequence of unicode characters) I do prefer "" while I prefer to use <<>> when I am dealing with random binary garbdata.

Qqwy

Qqwy

TypeCheck Core Team

As string combining ({"", &<>/2}) forms a Monoid (Just like:

  • {0, &+/2},
  • {1, &*/2},
  • {false, &Kernel.||/2}
  • {[], &++/2},
  • {%{}, &Map.merge/2},
  • {MapSet.new(), &MapSet.union/2}
    et cetera…
    ) , both String.empty/0 and String.append/2 would be wonderful functions to have, making this behaviour more explicit :grin:.
NobbZ

NobbZ

By that argumentation we also need Integer.one/0, Integer,zero/0, Integer.multiply/2, Integer.plus/2, List.empty/0, List.append/2, Map.empty/0, et cetera.

Monoids are true in elixir as they are in haskell, but not such a big thing. Also the monoid just works, regardles of using String.empty/0 or "".

I have to admit, sometimes one wants to/has to pass a function which returns the neutral of a monoid and since writing &("") or &""/1 isn’t possible, we have to use fn -> "" end, but that cases are so rare, that I do not think that there is really a benefit of adding such functions.

NobbZ

NobbZ

Also I have jsut discovered that there has been a PR closed by José:

https://github.com/elixir-lang/elixir/pull/6235

alisinabh

alisinabh OP

No, I think you didn’t got my point.

There are UTF-8 chars that are not visible. Like half space in Arabic and etc.
Since i write code with Persian strings in it, there is a common mistake that i press alt+Space that generates a half space which is not visible.

Here is an ordinary double quote → ""
Here is a half space between two double quotes → "‌"

Can you tell which one is the real empty one?

This problem is not affecting integers or list nor any other data type.[quote=“NobbZ, post:7, topic:6203”]
Also I have jsut discovered that there has been a PR closed by José:
[/quote]

As @josevalim commented in this PR today:

If this is a widespread problem, then we need to make sure those chars show up when inspected by default, rather than adding functions that return pre-built strings.

He suggested to tackle this issue by using a good string inspection that shows these things.

NobbZ

NobbZ

You diodn’t got whom I answered :wink: That was in direct resonse to @Qqwy comment about beeing {"", &<>/2} a monoid.

But in general, I think you are right, invisible characters are indeed a problem, but in my opinion, they are not a problem of a language. They are a problem of your editor and the display engine used therein.

Just consider C, they don’t have a function which creates an empty string, but can run into even worse trouble than we could when there are random invisible characters in their strings when they don’t expect them.

alisinabh

alisinabh OP

Sorry about that :sweat_smile:

I’m seeking an atom package that shows whitespaces. :slight_smile:

I just ran into this issue yesterday and it was frustrating to find out about that whitespace in my string.

Since i was a .NET developer before Elixir and back there it has string.Empty constant i thought maybe it’s a good idea here too.

But since that whitespace can happen in any other strings force showing them in editor will be a good idea. And since there are not lots of people using a keyboard with this kind of layout adding String.empty/0 does not make sense.

Thank’s

OvermindDL1

OvermindDL1

That is because C does not have standard strings, it has char-array’s at best.

C++ on the other hand does have an empty string, it is called string(). :slight_smile:

As well as a lot of C and C++ libraries that have strings do indeed add an empty global constant string variable.

I like seeing invisible chars, but I’ve not seen one that shows invisible unicode characters yet, if you find one that shows that, please tell me!

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