dsl

Value Members

1. object Dsl

   

2. object annotations

   

   The namespace that contains annotations of control operators for delimited continuation.

   The namespace that contains annotations of control operators for delimited continuation.

   All annotations defined here requires the Scala compiler plugin, which can be added in build.sbt:

   addCompilerPlugin("com.thoughtworks.dsl" %% "compilerplugin" % "latest.release")
   

   Example of definition of shift control operator

   Given a class that contains a doShift method, which is marked as @shift

   import com.thoughtworks.dsl.annotations.{reset, shift}
   implicit class ShiftOps[R, A](f: (A => R) => R) {
     def cpsApply(handler: A => R): R = f(handler)
     @shift def doShift: A = sys.error("Calls to this method should have been translated to `cpsApply`")
   }

   Example:

   1. When creating a @reset block that contains the doShift method, then the doShift method should be translated to cpsApply with a handler of captured rest code in the method,

      val explicitResetResult = {
        val i: Int = { (handler: Int => Int) =>
          handler(4) + 2
        }.doShift
        i * 10
      }: @reset
      explicitResetResult should be {
        ShiftOps { (handler: Int => Int) =>
          handler(4) + 2
        }.cpsApply { i =>
          i * 10
        }
      }
      explicitResetResult should be(42)

      and the result differs if you move the reset annotation.

      val explicitResetResult2 = {
        val i: Int = { (handler: Int => Int) =>
          handler(4) + 2
        }.doShift : @reset
        i * 10
      }
      explicitResetResult2 should be {
        val i = ShiftOps { (handler: Int => Int) =>
          handler(4) + 2
        }.cpsApply(identity)
        i * 10
      }
      explicitResetResult2 should be(60)

   Note

   If you omit an explicit reset annotation,

   def automaticallyReset: Int = {
     val i: Int = { (handler: Int => Int) =>
       handler(4) + 2
     }.doShift
     i * 10
   }

   then the reset operation will be performed on the enclosing method or function automatically.

   automaticallyReset should be {
     ShiftOps { (handler: Int => Int) =>
       handler(4) + 2
     }.cpsApply { i =>
       i * 10
     }
   }
   automaticallyReset should be(42)

   See also

   Dsl.Instruction for a sophisticated implementation of cpsApply.

3. package domains

   

4. package instructions