TryT

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[_]])