Tilde in Scala found in Scalatra example code

Question

Just ran into this sample code learning about Commands in Scalatra:

 protected def handle: Handler  = {
    case c: CreateTodoCommand => 
      add(newTodo(~c.name.value))
  }

In this particular case, what exactly is the relevance of ~ in ~c.name.value? Not sure where to find more documentation on this particular symbol.

Community · Accepted Answer · 2017-05-23 12:33:36Z

7

In Scala:

~x

translates to

x.unary_~

(this also applies to +,- and ! as explained in this post). So your example translates to:

add(newTodo(c.name.value.unary_~))

The documentation can hence be found at the type of value.

edited May 23, 2017 at 12:33

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answered Jun 17, 2013 at 21:11

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1 Comment

Verneri Åberg Over a year ago

I have the same problem even with the knowledge that ~x would be x.unary_~. As in this case: f: Field[T] and f.value : Option[T] and as far as i see there is no unary operator ~on vanilla Options, so i was wondering if there was a missing implicit conversion at work in here.

Verneri Åberg · Accepted Answer · 2014-02-17 13:49:49Z

0

it seems to be related to the block of code commented out in here: https://github.com/scalatra/scalatra/blob/2.2.x_2.9/core/src/main/scala/org/scalatra/package.scala

that is the only unary tilde operator if found that could be working here. the others seem to mainly be bitwise not operators

It actually seems that this might also be some import from scalaz library, tho the import statements are missing. similar uses of ~Option[_] can be found elsewhere as well...

edited Feb 17, 2014 at 13:49

answered Feb 17, 2014 at 10:00

Verneri Åberg

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