Re: Re: [scala] pattern matching with type parameters

> This is equivalent to reifying types on the JVM.
>
> It's hard to overstate the magnitude of this change. Let's just say ... it's
> not trivial.
>
> I'd rather see selective reification, along the lines of how you can
> selectively annotate types with @specialized.
>
> --j
>
> On Thu, May 28, 2009 at 4:42 PM, Alex Boisvert <boisvert@...> wrote:
>>
>> (Damn these send buttons that triggers by themselves!!  Here's what I was
>> writing...)
>>
>> It seems manifests are quite important and generally useful to support
>> good OO practices.
>>
>> Why not have one scala.reflect.Manifest automatically added to all Scala
>> classes for each type parameter and type member?
>>
>> Would this be such a memory or performance burden?   And if it is, maybe
>> we could have an annotation to disable the feature?
>>
>> I'm feeling we're going down the boilerplate road with this... maybe when
>> manifests are fully fleshed out and no longer experimental they could be
>> tightly integrated in the language?
>>
>> alex
>>
>>
>> On Thu, May 28, 2009 at 4:37 PM, Alex Boisvert <boisvert@...>
>> wrote:
>>>
>>> (Moving to -debate since I'm asking controversial question...)
>>>
>>> It seems manifest are quite important for
>>>
>>> Why not have one scala.reflect.Manifest automatically added to all Scala
>>> classes for each type parameter and type member?
>>>
>>> Would this be such a memory or performance burden?   And if it is, maybe
>>> we could have an annotation to disable the feature.
>>>
>>>
>>>
>>> On Thu, May 28, 2009 at 4:29 PM, David Hall <dlwh@...> wrote:
>>>>
>>>> scala> case class Msg[T](implicit val manifest:
>>>> scala.reflect.Manifest[T])
>>>> defined class Msg
>>>>
>>>> scala> case class StrMsg(s: String) extends Msg[String];
>>>> defined class StrMsg
>>>>
>>>> scala> (StrMsg("3"):Msg[String]) match { case m@ Msg() =>
>>>> println(m.manifest) }
>>>> java.lang.String
>>>>
>>>> Not perfect, but it's a start.
>>>>
>>>> -- David
>>>>
>>>> On Thu, May 28, 2009 at 4:24 PM, PetarM <petarm@...> wrote:
>>>> >
>>>> > Hi all,
>>>> >
>>>> > Is it possible to pattern match case classes with type parameters.
>>>> > E.g. if I
>>>> > have
>>>> >
>>>> >  case class Msg[T]()
>>>> >
>>>> > Can I have a match like this:
>>>> >
>>>> >  receive {
>>>> >    case Msg[T] => ... some code that uses the type information T ...
>>>> >  }
>>>> >
>>>> > I know that the code above does not compile, but is there a way to
>>>> > mimic its
>>>> > meaning?
>>>> >
>>>> > Thanks,
>>>> > Petar
>>>> >
>>>> >
>>>> > --
>>>> > View this message in context:
>>>> > http://www.nabble.com/pattern-matching-with-type-parameters-tp23771884p23771884.html
>>>> > Sent from the Scala mailing list archive at Nabble.com.
>>>> >
>>>> >
>>>
>>
>
>