Present

zio.blocks.maybe.Present

See thePresent companion object

final class Present[+A](val value: A)

Wraps a value so that "present of absent" is distinguishable from absent.

Maybe[+A] is an opaque type alias for A | Absent.type | Present[A]. A plain non-absent value of type A is a present Maybe[A] with zero allocation; the Absent singleton is Maybe.absent; and Present(a) is a present Maybe[A] whose value is a — used to represent "present of absent" in nested Maybes (e.g. Maybe.present(Maybe.absent)), which a bare Absent cannot express.

NOTE on soundness: Maybe.present (and only present) wraps a user-supplied Present[_] argument in an extra Present layer (present(Present(x)) == Present(Present(x))). This ensures unsafeGet (used by codecs) returns the correct inner Present(x) without double-unwrapping. The public case Present(v) / case Absent matching idiom is unaffected.

Attributes

Companion: object
Source: Maybe.scala
Graph
Supertypes: class Object

trait Matchable

class Any

Members list

Value members

Concrete methods

Compares the receiver object (this) with the argument object (that) for equivalence.

Any implementation of this method should be an equivalence relation:

It is reflexive: for any instance x of type Any, x.equals(x) should return true.
It is symmetric: for any instances x and y of type Any, x.equals(y) should return true if and only if y.equals(x) returns true.
It is transitive: for any instances x, y, and z of type Any if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.

If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is usually necessary to override hashCode to ensure that objects which are "equal" (o1.equals(o2) returns true) hash to the same scala.Int. (o1.hashCode.equals(o2.hashCode)).

Value parameters

that: the object to compare against this object for equality.

Attributes

Returns: true if the receiver object is equivalent to the argument; false otherwise.
Definition Classes: Any
Source: Maybe.scala

Calculates a hash code value for the object.

The default hashing algorithm is platform dependent.

Note that it is allowed for two objects to have identical hash codes (o1.hashCode.equals(o2.hashCode)) yet not be equal (o1.equals(o2) returns false). A degenerate implementation could always return 0. However, it is required that if two objects are equal (o1.equals(o2) returns true) that they have identical hash codes (o1.hashCode.equals(o2.hashCode)). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the equals method.

Attributes

Returns: the hash code value for this object.
Definition Classes: Any
Source: Maybe.scala

Returns a string representation of the object.

The default representation is platform dependent.

Attributes

Returns: a string representation of the object.
Definition Classes: Any
Source: Maybe.scala

Concrete fields

Attributes

Source: Maybe.scala

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