Packages

final class Ref[A] extends AnyVal with Serializable

A mutable atomic reference for the IO monad. This is the IO equivalent of a volatile var, augmented with atomic operations, which make it useful as a reasonably efficient (if low-level) concurrency primitive.

for {
  ref <- Ref.make(2)
  v   <- ref.update(_ + 3)
  _   <- console.putStrLn("Value = " + v) // Value = 5
} yield ()

NOTE: While Ref provides the functional equivalent of a mutable reference, the value inside the Ref should be immutable. For performance reasons Ref is implemented in terms of compare and swap operations rather than synchronization. These operations are not safe for mutable values that do not support concurrent access.

Linear Supertypes
Serializable, Serializable, AnyVal, Any
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Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    Any
  2. final def ##(): Int
    Definition Classes
    Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    Any
  4. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  5. def get: UIO[A]

    Reads the value from the Ref.

    Reads the value from the Ref.

    returns

    UIO[A] value from the Ref

  6. def getAndSet(a: A): UIO[A]

    Atomically writes the specified value to the Ref, returning the value immediately before modification.

    Atomically writes the specified value to the Ref, returning the value immediately before modification. This is not implemented in terms of modify purely for performance reasons.

    a

    value to be written to the Ref

    returns

    UIO[A] value of the Ref immediately before modification

  7. def getAndUpdate(f: (A) ⇒ A): UIO[A]

    Atomically modifies the Ref with the specified function, returning the value immediately before modification.

    Atomically modifies the Ref with the specified function, returning the value immediately before modification. This is not implemented in terms of modify purely for performance reasons.

    f

    function to atomically modify the Ref

    returns

    UIO[A] value of the Ref immediately before modification

  8. def getAndUpdateSome(pf: PartialFunction[A, A]): UIO[A]

    Atomically modifies the Ref with the specified partial function, returning the value immediately before modification.

    Atomically modifies the Ref with the specified partial function, returning the value immediately before modification. If the function is undefined on the current value it doesn't change it.

    pf

    partial function to atomically modify the Ref

    returns

    UIO[A] value of the Ref immediately before modification

  9. def getClass(): Class[_ <: AnyVal]
    Definition Classes
    AnyVal → Any
  10. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  11. def modify[B](f: (A) ⇒ (B, A)): UIO[B]

    Atomically modifies the Ref with the specified function, which computes a return value for the modification.

    Atomically modifies the Ref with the specified function, which computes a return value for the modification. This is a more powerful version of update.

    B

    type of the value of the Ref to be modified

    f

    function which computes a return value for the modification

    returns

    UIO[B] modified value the Ref

  12. def modifySome[B](default: B)(pf: PartialFunction[A, (B, A)]): UIO[B]

    Atomically modifies the Ref with the specified partial function, which computes a return value for the modification if the function is defined in the current value otherwise it returns a default value.

    Atomically modifies the Ref with the specified partial function, which computes a return value for the modification if the function is defined in the current value otherwise it returns a default value. This is a more powerful version of updateSome.

    B

    type of the value of the Ref to be modified

    default

    default value to be returned if the partial function is not defined on the current value

    pf

    partial function to be computed on the current value if defined on the current value

    returns

    UIO[B] modified value of the Ref

  13. def set(a: A): UIO[Unit]

    Writes a new value to the Ref, with a guarantee of immediate consistency (at some cost to performance).

    Writes a new value to the Ref, with a guarantee of immediate consistency (at some cost to performance).

    a

    value to be written to the Ref

    returns

    UIO[Unit]

  14. def setAsync(a: A): UIO[Unit]

    Writes a new value to the Ref without providing a guarantee of immediate consistency.

    Writes a new value to the Ref without providing a guarantee of immediate consistency.

    a

    value to be written to the Ref

    returns

    UIO[Unit]

  15. def toString(): String
    Definition Classes
    Ref → Any
  16. def update(f: (A) ⇒ A): UIO[Unit]

    Atomically modifies the Ref with the specified function.

    Atomically modifies the Ref with the specified function. This is not implemented in terms of modify purely for performance reasons.

    f

    function to atomically modify the Ref

    returns

    UIO[Unit]

  17. def updateAndGet(f: (A) ⇒ A): UIO[A]

    Atomically modifies the Ref with the specified function and returns the updated value.

    Atomically modifies the Ref with the specified function and returns the updated value. This is not implemented in terms of modify purely for performance reasons.

    f

    function to atomically modify the Ref

    returns

    UIO[A] modified value of the Ref

  18. def updateSome(pf: PartialFunction[A, A]): UIO[Unit]

    Atomically modifies the Ref with the specified partial function.

    Atomically modifies the Ref with the specified partial function. If the function is undefined on the current value it doesn't change it.

    pf

    partial function to atomically modify the Ref

    returns

    UIO[Unit]

  19. def updateSomeAndGet(pf: PartialFunction[A, A]): UIO[A]

    Atomically modifies the Ref with the specified partial function.

    Atomically modifies the Ref with the specified partial function. If the function is undefined on the current value it returns the old value without changing it.

    pf

    partial function to atomically modify the Ref

    returns

    UIO[A] modified value of the Ref

Inherited from Serializable

Inherited from Serializable

Inherited from AnyVal

Inherited from Any

Ungrouped