scalaz

com.thoughtworks.dsl.domains.scalaz$
object scalaz

Contains interpreters to enable !-notation for Monadic and other keywords in code blocks whose type support scalaz.Bind, scalaz.MonadError and scalaz.MonadTrans.

Attributes

Authors:

杨博 (Yang Bo)

Example:

scalaz.Free#Trampoline is a monadic data type that performs tail call optimization. It can be built from a @[[Dsl.reset reset]] code block within some !-notation, similar to the each method in ThoughtWorks Each.

 import _root_.scalaz.Trampoline
 import _root_.scalaz.Free.Trampoline
 import com.thoughtworks.dsl.keywords.Monadic
 import com.thoughtworks.dsl.domains.scalaz.given
 import com.thoughtworks.dsl.macros.Reset.Default.reset
 import com.thoughtworks.dsl.keywords.Monadic.unary_!
 val trampoline3 = Trampoline.done(3)
 def dslSquare = reset(Trampoline.delay {
   s"This string is produced by a trampoline: ${!trampoline3 * !trampoline3}"
 })
 dslSquare.run should be("This string is produced by a trampoline: 9")

!trampoline3 is a shortcut of !Monadic(trampoline3), enabled by import com.thoughtworks.dsl.keywords.Monadic.given, which will be converted to flatMap calls by our DSL interpreter. Thus, the method dslSquare is equivalent to the following code in scalaz.syntax:

 def scalazSyntaxSquare = trampoline3.flatMap { tmp1 =>
   trampoline3.flatMap { tmp2 =>
     Trampoline.delay {
       s"This string is produced by a trampoline: ${tmp1 * tmp2}"
     }
   }
 }
 scalazSyntaxSquare.run should be("This string is produced by a trampoline: 9")

A @[[Dsl.reset reset]] code block can contain try / catch / finally if the monadic data type supports scalaz.MonadError. tryt.scala is a monad transformer that provides scalaz.MonadError, therefore try / catch / finally expressions can be used inside a @[[Dsl.reset reset]] code block whose return type is TryT[Trampoline, ?].

 import com.thoughtworks.tryt.invariant.TryT, TryT.given
 import scala.util.{Try, Success}
 type TryTTransfomredTrampoline[A] = TryT[Trampoline, A]
 val trampolineSuccess0: TryTTransfomredTrampoline[Int] = TryT(Trampoline.done(Try(0)))
 def dslTryCatch: TryTTransfomredTrampoline[String] = reset(TryT(Trampoline.delay(Try {
   try {
     s"Division result: ${!trampoline3 / !trampolineSuccess0}"
   } catch {
     case e: ArithmeticException =>
       s"Cannot divide ${!trampoline3} by ${!trampolineSuccess0}"
   }
 })))
 inside(dslTryCatch) {
   case TryT(trampoline) =>
     trampoline.run should be(Success("Cannot divide 3 by 0"))
 }

Note that !-notation can be used on both trampoline3 and trampolineSuccess0 even when they are different types, i.e. trampoline3 is a vanilla Trampoline, while trampolineSuccess0 is a TryT-transfomred Trampoline. It is possible because the interpreters of the keywords.Monadic invoke scalaz.MonadTrans.liftM automatically. The above dslTryCatch method is equivalent to the following code in scalaz.syntax:

 import _root_.scalaz.syntax.monad._
 def scalazSyntaxTryCatch: TryTTransfomredTrampoline[String] = {
   import _root_.scalaz.syntax.monadError._
   trampoline3.liftM[TryT].flatMap { tmp0 =>
     trampolineSuccess0.flatMap { tmp1 =>
       TryT(Trampoline.delay(Try(s"Division result: ${tmp0 / tmp1}")))
     }
   }.handleError {
     case e: ArithmeticException =>
       trampoline3.liftM[TryT].flatMap { tmp2 =>
         trampolineSuccess0.flatMap { tmp3 =>
           TryT(Trampoline.delay(Try(s"Cannot divide ${tmp2} by ${tmp3}")))
         }
       }
     case e =>
       e.raiseError[TryTTransfomredTrampoline, String]
   }
 }
 inside(scalazSyntaxTryCatch) {
   case TryT(trampoline) =>
     trampoline.run should be(Success("Cannot divide 3 by 0"))
 }
Source:
scalaz.scala
Graph
Supertypes
class Object
trait Matchable
class Any
Self type
scalaz.type

Members list

Concise view

Givens

Givens

given given_DslComposer_F_A_F[F[_], A, B](using monadError: MonadThrowable[F]): DslComposer[F[B], A, F[A]]

Attributes

Source:
scalaz.scala
given given_OneStep_G_F[F[_[_], _], G[_], A, B](using monadTrans: MonadTrans[F], monad: Monad[G]): OneStep[G[A], F[G, A]]

Attributes

Source:
scalaz.scala
given given_Original_Monadic_F_A[F[_], A, G[_], B](using monad: Bind[F], lift: Lift[G[A], F[A]]): Original[Monadic[G[A]], F[B], A]

The Dsl instance that converts a domains.Monadic keyword to the monad domain type then flatMap. This instance helps when the keyword supports a domain D that can be lifted to the F[A], while there is not general rule to derive F[A] from D. For example, when F[A] is a monad transformer and D is the underlying monad type.

The Dsl instance that converts a domains.Monadic keyword to the monad domain type then flatMap. This instance helps when the keyword supports a domain D that can be lifted to the F[A], while there is not general rule to derive F[A] from D. For example, when F[A] is a monad transformer and D is the underlying monad type.

Attributes

Source:
scalaz.scala

Inherited givens

given given_OneStep_A_F[F[_], A, B](using applicative: Applicative[F]): OneStep[A, F[A]]

Attributes

Inherited from:
LowPriority0 (hidden)
Source:
scalaz.scala
given given_StackUnsafe_K_F_A[F[_], K, A, G[_], B](using monad: Monad[F], lift: Lift[G[A], F[A]], dsl: Searching[K, G[A], A], liftG: Lift[A, G[A]]): StackUnsafe[K, F[B], A]

The Dsl instance that converts a keyword to the monad domain type then flatMap. This instance helps when the keyword supports a domain D that can be lifted to the F[A], while there is not general rule to derive F[A] from D. For example, when F[A] is a monad transformer and D is the underlying monad type.

The Dsl instance that converts a keyword to the monad domain type then flatMap. This instance helps when the keyword supports a domain D that can be lifted to the F[A], while there is not general rule to derive F[A] from D. For example, when F[A] is a monad transformer and D is the underlying monad type.

Attributes

Inherited from:
LowPriority0 (hidden)
Source:
scalaz.scala