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object invariant

The namespace that contains the invariant TryT.

Source
covariant.scala
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Type Members

  1. type TryT[F[_], A] = invariant.OpacityTypes.TryT[F, A]

    A monad transformer for exception handling.

    A monad transformer for exception handling.

    Example:

    1. As a monad transformer, TryT should be used with another monadic data type, like scalaz.Name.

      import scalaz.Name
import com.thoughtworks.tryt.invariant.TryT, TryT._

type TryName[A] = TryT[Name, A]

      Given a validate function,

      def validate(s: String): Int = s.toInt

      when creating a TryT-transformed scalaz.Name from the validate,

      import scalaz.syntax.all._
val invalidTry: TryName[Int] = validate("invalid input").point[TryName]

      then the exceptions thrown in validate call should be converted to a scala.util.Failure;

      import com.thoughtworks.tryt.invariant.TryT._

val TryT(Name(failure)) = invalidTry

import scala.util._
failure should be(an[Failure[_]])

      and when there is no exception thrown in validate call,

      val validTry: TryName[Int] = validate("42").point[TryName]

      then the result of validate call should be converted to a scala.util.Success;

      val TryT(Name(success)) = validTry
success should be(Success(42))

      and when the TryT-transformed scalaz.Name is built from a for-comprehension,

      val invalidForComprehension: TryName[Int] = for {
  i <- validate("42").point[TryName]
  j <- validate("invalid input").point[TryName]
} yield i + j

      then the exceptions thrown in the for-comprehension should be converted to a scala.util.Failure;

      val TryT(Name(failure2)) = invalidTry
failure2 should be(an[Failure[_]])
    Note

    This TryT type is an opacity alias to F[Try[A]]. All type classes and helper functions for this TryT type are defined in the companion object TryT

    See also

    This TryT transfomer is similar to scalaz.EitherT, except TryT handles exceptions thrown in callback functions passed to map, bind or point.

Value Members

  1. final def !=(arg0: Any): Boolean
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  2. final def ##(): Int
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  3. final def ==(arg0: Any): Boolean
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  4. final def asInstanceOf[T0]: T0
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  5. def clone(): AnyRef
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  6. final def eq(arg0: AnyRef): Boolean
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  7. def equals(arg0: Any): Boolean
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  8. def finalize(): Unit
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  9. final def getClass(): Class[_]
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  10. def hashCode(): Int
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  11. final def isInstanceOf[T0]: Boolean
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  12. final def ne(arg0: AnyRef): Boolean
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  13. final def notify(): Unit
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  14. final def notifyAll(): Unit
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  15. final def synchronized[T0](arg0: ⇒ T0): T0
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  16. def toString(): String
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  17. final def wait(): Unit
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  18. final def wait(arg0: Long, arg1: Int): Unit
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  19. final def wait(arg0: Long): Unit
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  20. object TryT extends TryTInstances0 with InvariantInstances

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