a recent interpreter session

Very cool....

Does that work in regular Scala programs or only in the interpreter?

On Wed, May 27, 2009 at 6:03 PM, Paul Phillips <paulp [at] improving [dot] org> wrote:

Who wants structural type inference! If you raised your hand you are
very sick.  And yet..

scala> typify(classOf[List[_]], classOf[java.util.List[_]])
res0: String =
{
 def hashCode(): Int
 def equals(p1: AnyRef): Boolean
 def indexOf(p1: AnyRef): Int
 def lastIndexOf(p1: AnyRef): Int
 def contains(p1: AnyRef): Boolean
 def size(): Int
 def isEmpty(): Boolean
}

scala> mkType("AnyList", res0)
defined type alias AnyList
res1: scala.tools.nsc.InterpreterResults.Result = Success

scala> var x: AnyList = List("a", "b").asInstanceOf[AnyList]
x: AnyList = List(a, b)

scala> x contains "a"
res2: Boolean = true

scala> x = new java.util.ArrayList[String]()
x: AnyList = []

scala> x.isEmpty
res3: Boolean = true

--
Paul Phillips      | We must respect the other fellow's religion, but only
Apatheist          | in the sense and to the extent that we respect his
Empiricist         | theory that his wife is beautiful and his children smart.
ha! spill, pupil   |     -- H. L. Mencken

--
http://erikengbrecht.blogspot.com/

On Wed, May 27, 2009 at 06:10:32PM -0400, Erik Engbrecht wrote:
> Does that work in regular Scala programs or only in the interpreter?

Scala does not offer any direct mechanism for making a type out of a
string, so everything in my bag of tricks will require either the
interpreter or staged compilation. So it is faked, but it's plausible
it could be faked so well you'd forget what was really happening.

On Wednesday May 27 2009, Paul Phillips wrote:
> On Wed, May 27, 2009 at 06:10:32PM -0400, Erik Engbrecht wrote:
> > Does that work in regular Scala programs or only in the
> > interpreter?
>
> Scala does not offer any direct mechanism for making a type out of a
> string, so everything in my bag of tricks will require either the
> interpreter or staged compilation. So it is faked, but it's
> plausible it could be faked so well you'd forget what was really
> happening.

Any sufficiently advanced technology is indistinguishable from magic.
Or a rigged demo.

RRS