SequenceMultipleReadable

This mixin provides a way to sequence the multiple readables whose return value is a container of some sort. For more info, see A Traversable from Haskell wiki or look up sequence, etc. For now, let's provide an example. Assuming we have an object StrToIntList that takes a string and produces a try of a list of integers by splitting and then parsing the ints. The result is either a success or failure but either way, the result is wrapped in a try container. Notice, that we included in the definition, with SequenceMultipleReadable[ReadableSource, Try, List[Int]]. This is all that is required at definition time to get the sequencing that we want.

The calling code (once the proper type class instances are in imported into the implicit scope) simply passes the container of objects to fromSequencedMultipleSources and the result is a Try[Stream[List[Int]]].

object StrToIntList
  extends ReadableByString[Try[List[Int]]]
  with MultipleAlohaReadable[Try[List[Int]]]
  with SequenceMultipleReadable[ReadableSource, Try, List[Int]] {

  def fromString(s: String): Try[List[Int]] = Try {
    if (s.trim == "") List.empty
    else s.trim.split("""\s*,\s*""", -1).map(_.toInt).toList
  }
}

// ======   Calling code   ==============================================================================

import scalaz.std.stream.streamInstance                  // Provides (non-strict) Traverse type class for Stream
import com.eharmony.aloha.util.TryScalazMonad   // Provides Applicative type class for Try

val in = Stream("1, 11, 111",
                "2, BAD",
                "3, 33, 333")

// This is the thing to notice:  we get a Try[Stream[List[Int]]] and not a Stream[Try[List[Int]]].  This is
// why this function is here.  It commutes the container types.  And because the Stream is non-strict, there is no
// attempt to parse the 3rd string "3, 33, 333" since an error occurred before getting to the third element.
// This behaviour can change for strict Traverse object (like the Traverse for List).
//
val out: Try[Stream[List[Int]]] = StrToIntList.fromSequencedMultipleSources(in)

// Test the error occurred.
val exceptionMsg = """For input string: "BAD""""
require(out.isFailure && exceptionMsg == out.failed.get.getMessage, "Should have failed.")

APP: A applicative functor container type (see Functors, Monads, Applicatives – can be so simple).
B: The container type in the output

Self Type: SequenceMultipleReadable[A, APP, B] with MultipleReadable[A, APP[B]]

Linear Supertypes

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Known Subclasses

ModelFactory, ModelFactoryImpl

Value Members

final def !=(arg0: AnyRef): Boolean

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final def !=(arg0: Any): Boolean

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final def ##(): Int

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final def ==(arg0: AnyRef): Boolean

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final def ==(arg0: Any): Boolean

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final def asInstanceOf[T0]: T0

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def clone(): AnyRef

Attributes
protected[java.lang]
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@throws( ... )
final def eq(arg0: AnyRef): Boolean

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def equals(arg0: Any): Boolean

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def finalize(): Unit

Attributes
protected[java.lang]
Definition Classes
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@throws( classOf[java.lang.Throwable] )
def fromSequencedMultipleSources[T[_]](readableTypes: T[A])(implicit t: Traverse[T], ap: Applicative[APP]): APP[T[B]]

Produce multiple outputs from multiple inputs and sequence the data so that we commute that container types.
Produce multiple outputs from multiple inputs and sequence the data so that we commute that container types. For an example, see that trait documentation.
T
the Traverse container type
readableTypes
A container of readable sources to convert to outputs.
t
a Traverse type class instance
ap
an applicative function type class instance
returns
final def getClass(): Class[_]

Definition Classes
AnyRef → Any
def hashCode(): Int

Definition Classes
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final def isInstanceOf[T0]: Boolean

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Any
final def ne(arg0: AnyRef): Boolean

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final def notify(): Unit

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final def notifyAll(): Unit

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final def synchronized[T0](arg0: ⇒ T0): T0

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def toString(): String

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final def wait(): Unit

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Annotations
@throws( ... )
final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
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Annotations
@throws( ... )
final def wait(arg0: Long): Unit

Definition Classes
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Annotations
@throws( ... )

trait SequenceMultipleReadable[A <: ReadableSource, APP[_], B] extends AnyRef

Value Members

final def !=(arg0: AnyRef): Boolean

final def !=(arg0: Any): Boolean

final def ##(): Int

final def ==(arg0: AnyRef): Boolean

final def ==(arg0: Any): Boolean

final def asInstanceOf[T0]: T0

def clone(): AnyRef

final def eq(arg0: AnyRef): Boolean

def equals(arg0: Any): Boolean

def finalize(): Unit

def fromSequencedMultipleSources[T[_]](readableTypes: T[A])(implicit t: Traverse[T], ap: Applicative[APP]): APP[T[B]]

final def getClass(): Class[_]

def hashCode(): Int

final def isInstanceOf[T0]: Boolean

final def ne(arg0: AnyRef): Boolean

final def notify(): Unit

final def notifyAll(): Unit

final def synchronized[T0](arg0: ⇒ T0): T0

def toString(): String

final def wait(): Unit

final def wait(arg0: Long, arg1: Int): Unit

final def wait(arg0: Long): Unit

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