1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
|
scala> import scala.language.experimental.macros, scala.reflect.macros.blackbox.Context
import scala.language.experimental.macros
import scala.reflect.macros.blackbox.Context
scala> def macroImpl[T: c.WeakTypeTag](c: Context)(t: c.Expr[T]): c.Expr[List[T]] = {
val r = c.universe.reify { List(t.splice) }
c.Expr[List[T]]( c.untypecheck(r.tree) )
}
macroImpl: [T](c: scala.reflect.macros.blackbox.Context)(t: c.Expr[T])(implicit evidence$1: c.WeakTypeTag[T])c.Expr[List[T]]
scala> def demo[T](t: T): List[T] = macro macroImpl[T]
defined term macro demo: [T](t: T)List[T]
scala> def m[T](t: T): List[List[T]] =
demo( List((t,true)) collect { case (x,true) => x } )
m: [T](t: T)List[List[T]]
scala> m(List(1))
res0: List[List[List[Int]]] = List(List(List(1)))
scala> // Showing we haven't added unreachable warnings
scala> List(1) collect { case x => x }
res1: List[Int] = List(1)
scala> List("") collect { case x => x }
res2: List[String] = List("")
scala> :quit
|
