opt

Documentation

Overview

Package opt provides the generic Maybe type for representing optional values without pointers.

Index

• type Maybe
  • func FromPtr[V any](ptr *V) Maybe[V]
  • func None[V any]() Maybe[V]
  • func Some[V any](value V) Maybe[V]
  • func (m Maybe[V]) AsPtr() *V
  • func (m Maybe[V]) IsDefined() bool
  • func (m Maybe[V]) MarshalJSON() ([]byte, error)
  • func (m Maybe[V]) OrElse(valueIfUndefined V) V
  • func (m Maybe[V]) String() string
  • func (m *Maybe[V]) UnmarshalJSON(data []byte) error
  • func (m Maybe[V]) Value() V

Types

type Maybe

type Maybe[V any] struct {
	// contains filtered or unexported fields
}

Maybe is a simple implementation of an optional value type.

func FromPtr

func FromPtr[V any](ptr *V) Maybe[V]

FromPtr returns a Maybe that has a defined value of *ptr if ptr is non-nil, or no value if ptr is nil.

func None

func None[V any]() Maybe[V]

None returns a Maybe with no value.

func Some

func Some[V any](value V) Maybe[V]

Some returns a Maybe that has a defined value.

func (Maybe[V]) AsPtr

func (m Maybe[V]) AsPtr() *V

AsPtr returns a pointer to the value if the value is defined, or nil otherwise.

func (Maybe[V]) IsDefined

func (m Maybe[V]) IsDefined() bool

IsDefined returns true if the Maybe has a value.

func (Maybe[V]) MarshalJSON

func (m Maybe[V]) MarshalJSON() ([]byte, error)

MarshalJSON produces whatever JSON representation would normally be produced for the value if a value is defined, or a JSON null otherwise.

func (Maybe[V]) OrElse

func (m Maybe[V]) OrElse(valueIfUndefined V) V

OrElse returns the value of the Maybe if any, or the valueIfUndefined otherwise.

func (Maybe[V]) String

func (m Maybe[V]) String() string

String returns a string representation of the value, or "[none]" if undefined. The string representation of a value is either its own String() if it has such a method, or else the result of fmt.Sprintf with "%v".

func (*Maybe[V]) UnmarshalJSON

func (m *Maybe[V]) UnmarshalJSON(data []byte) error

UnmarshalJSON sets the Maybe to None[V] if the data is a JSON null, or else unmarshals a value of type V as usual and sets the Maybe to Some(value).

func (Maybe[V]) Value

func (m Maybe[V]) Value() V

Value returns the value if a value is defined, or the zero value for the type otherwise.