What's the difference between Option and Some

Question
1

I noticed that in one of my exercises I did the following.

if ( something)
  Option(data)
else
  None

And it still worked. What is the difference between Option(data) and Some(data) ?
It seems that for the simple cases they are equal == .

2

Constructing with Option(x) will do a null-check on x, Some(x) does not and may therefore contain null as a value.

roughly:
Option(x) = if (x == null) None else Some(x)

Cheers,
Enno.

3 Likes
3

option(null) == Nonesome(null) == wrapping a null in an option
Gesendet: Dienstag, 21. März 2017 um 17:09 Uhr

Von: jimka <[email protected]>

An: [email protected]

Betreff: [Scala Users] [Question] What’s the difference between Option and Some jimka

March 21

I noticed that in one of my exercises I did the following.

if ( something)
  Option(data)
else
  None

And it still worked. What is the difference between Option(data) and Some(data) ? 

		It seems that for the simple cases they are equal == .</p>

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4

Option[A] is a type. Some(a): Option[A] and None: Option[Nothing] are instances of the type. The companion object for Option has an apply() method which is basically

   def apply(a: A): Option[A] = if (a == null) None else Some(a)

So if a isn’t null then Option(a) == Some(a) and if it is null then Option(a) == None.

Note that you can get yourself into trouble sometimes putting None first in certain constructs because Scala can’t figure out what the type A should be. An alternative to None that gives Scala more type information is Option.empty[String] (or Int or whatever type A you are after).

5

Hello,

Alternatively to Option.empty[A], you could also write None: Option[A].

 Best, Oliver
6

Hi @jimka
I found a very good Description about Option and how to work with in the effective Scala - Option from Twitter.
Think Option is a Collection with one or zero item. :smile:
Greetings Roebi

7

Also

Option(null) == None

But

Some(null) == Some(null)

Very important when dealing with Java data. Use Option() to convert
possible nulls into Options