Convert match statement to pattern matching anonymous function

[Oliver Ruebenacker]

     Hello,

  I have something a bit like this:

    val list = 1 to 10
    val list2 = list.map(i => i match {
      case 2 | 4 | 6 => i / 2
      case 3 | 9 => i / 3
      case _ => i
    })

  IntelliJ says I should "Convert match statement to pattern matching anonymous function". How would I do that? Thanks!

     Best, Oliver

--

Oliver Ruebenacker

Senior Software Engineer, Diabetes Portal, Broad Institute

[Kevin Wright]

It means:

  val list = 1 to 10

  val list2 = list map {

[Alexey Shuksto]

Also, you can just click inspection lightbulb or hit Alt-Enter and IDEA will convert it for you (as with many more code inspections).

[Clint Gilbert]

Aside: the reason this works is that a PartialFunction extends
Function1, and not the other way around. There are pros and cons to
this; the convenient syntax Kevin showed is one of the big pros.

On 06/16/2016 01:14 PM, Kevin Wright wrote:
> It means:
>
> val list = 1 to 10
> val list2 = list map {
> case 2 | 4 | 6 => i / 2
> case 3 | 9 => i / 3
> case _ => i
> }
>
>
>
> On 16 June 2016 at 17:55, Oliver Ruebenacker <cur...@gmail.com

> <mailto:cur...@gmail.com>> wrote:
>
>
> Hello,
>
> I have something a bit like this:
>
> val list = 1 to 10
> val list2 = list.map(i => i match {
> case 2 | 4 | 6 => i / 2
> case 3 | 9 => i / 3
> case _ => i
> })
>
> IntelliJ says I should "Convert match statement to pattern
> matching anonymous function". How would I do that? Thanks!
>
> Best, Oliver
>
> --
> Oliver Ruebenacker
> Senior Software Engineer, Diabetes Portal

> <http://www.type2diabetesgenetics.org/>, Broad Institute
> <http://www.broadinstitute.org/>
>
>
>
> --
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--

[Oliver Ruebenacker]

Well, "Cannot resolve symbol i".

[Clint Gilbert]

It's just a pattern match, like any other. If you need access to the
things that matched, name them with '@'. If that's not convenient, use
the i => i match { ... } form.

On 06/16/2016 01:54 PM, Oliver Ruebenacker wrote:
> Well, "Cannot resolve symbol i".
>
> On Thu, Jun 16, 2016 at 1:14 PM, Kevin Wright <kev.lee...@gmail.com
> <mailto:kev.lee...@gmail.com>> wrote:
>
> It means:
>
> val list = 1 to 10
> val list2 = list map {
> case 2 | 4 | 6 => i / 2
> case 3 | 9 => i / 3
> case _ => i
> }
>
>
>
> On 16 June 2016 at 17:55, Oliver Ruebenacker <cur...@gmail.com

> <mailto:cur...@gmail.com>> wrote:
>
>
> Hello,
>
> I have something a bit like this:
>
> val list = 1 to 10
> val list2 = list.map(i => i match {
> case 2 | 4 | 6 => i / 2
> case 3 | 9 => i / 3
> case _ => i
> })
>
> IntelliJ says I should "Convert match statement to pattern
> matching anonymous function". How would I do that? Thanks!
>
> Best, Oliver
>
> --
> Oliver Ruebenacker

> Senior Software Engineer, Diabetes Portal
> <http://www.type2diabetesgenetics.org/>, Broad Institute
> <http://www.broadinstitute.org/>
>
>
>
>
>
>

> --
> Oliver Ruebenacker

[Serge]

val list = 1 to 10
val list2 = list map {

  case i @ (2 | 4 | 6)  => i / 2
  case i @ (3 | 9)      => i / 3
  case i                => i
}

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[Oliver Ruebenacker]

Awesome, thanks! I did not know about the @ feature.

[Алексей Шуксто]

case i@(2 | 4 | 6) => i / 2

чт, 16 июня 2016, 21:54 Oliver Ruebenacker <cur...@gmail.com>:

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[Kevin Wright]

I’d like to say use a for-comprehension here, unfortunately type inference doesn’t work quite as you’d want.

So using the @ bind syntax:

  val list = 1 to 10

  val list2 = list map {

    case i @ ( 2 | 4 | 6 ) => i / 2
    case i @ ( 3 | 9 )     => i / 3
    case i                 => i
  }

Or if you wish to avoid magic numbers and capture more of the intent:

  val list2 = list map {

    case i if i % 2 == 0 => i / 2
    case i if i % 3 == 0 => i / 3
    case i               => i
  }

Kevin Wright
mail / hangouts / msn : kev.lee...@gmail.com

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"My point today is that, if we wish to count lines of code, we should not regard them as "lines produced" but as "lines spent": the current conventional wisdom is so foolish as to book that count on the wrong side of the ledger" ~ Dijkstra