option

Documentation

Index

• func Contains[T comparable](option Option[T], matches T) bool
• func Fold[T, R any](option Option[T], defaultValue R, f func(T) R) R
• func FoldLeft[T, R any](option Option[T], zero R, f func(accum R, value T) R) R
• type Option
  • func AsOptional[T comparable](v T) Option[T]
  • func CommaOk[T any](v T, ok bool) Option[T]
  • func FlatMap[T, R any](option Option[T], f func(T) Option[R]) Option[R]
  • func FromPointer[T any](v *T) Option[T]
  • func Map[T, R any](option Option[T], f func(T) R) Option[R]
  • func None[T any]() Option[T]
  • func Some[T any](v T) Option[T]
  • func (o Option[T]) Contains(predicate func(v T) bool) bool
  • func (o Option[T]) Empty() bool
  • func (o Option[T]) Equal(other Option[T]) bool
  • func (o Option[T]) ForAll(f func(v T))
  • func (o Option[T]) ForEach(predicate func(v T) bool) bool
  • func (o Option[T]) Get() (val T, ok bool)
  • func (o Option[T]) GetOrElse(alternative T) T
  • func (o Option[T]) GetOrElseF(alternative func() T) T
  • func (o Option[T]) MustGet() (rtn T)
  • func (o Option[T]) OrElse(alternative T) Option[T]
  • func (o Option[T]) Present() bool
  • func (o Option[T]) PtrOrNil() *T
  • func (o Option[T]) String() string

Functions

func Contains

func Contains[T comparable](option Option[T], matches T) bool

Contains returns true if the option is present and matches the given value

func Fold

func Fold[T, R any](option Option[T], defaultValue R, f func(T) R) R

Fold returns the result of f applied to the value if present, otherwise returns the defaultValue

func FoldLeft

func FoldLeft[T, R any](option Option[T], zero R, f func(accum R, value T) R) R

FoldLeft applies the binary operator f to the value if present, otherwise returns the zero value

Types

type Option

type Option[T any] struct {
	// contains filtered or unexported fields
}

Option is a type that represents a value that may or may not be present

It is different a normal value as it can distinguish between a zero value and a missing value even on pointer types

func AsOptional

func AsOptional[T comparable](v T) Option[T]

AsOptional returns an Option where a zero value T is considered None and any other value is considered Some

i.e.

AsOptional(nil) == None()
AsOptional(0) == None()
AsOptional(false) == None()
AsOptional("") == None()
AsOptional(&MyStruct{}) == Some(&MyStruct{})
AsOptional(1) == Some(1)
AsOptional(true) == Some(true)

func CommaOk

func CommaOk[T any](v T, ok bool) Option[T]

CommaOk is a helper function to convert a comma ok idiom into an Option. If ok is true it returns Some(v), otherwise it returns None.

func FlatMap

func FlatMap[T, R any](option Option[T], f func(T) Option[R]) Option[R]

FlatMap returns an Option with the value mapped by the given function if present, otherwise returns None

func FromPointer

func FromPointer[T any](v *T) Option[T]

FromPointer returns an Option where a nil pointer is considered None and any other value is considered Some, with the value dereferenced.

func Map

func Map[T, R any](option Option[T], f func(T) R) Option[R]

Map returns an Option with the value mapped by the given function if present, otherwise returns None

func None

func None[T any]() Option[T]

None returns an Option with no value set

func Some

func Some[T any](v T) Option[T]

Some returns an Option with the given value and present set to true

This means Some(nil) is a valid present Option and Some(nil) != None()

func (Option[T]) Contains

func (o Option[T]) Contains(predicate func(v T) bool) bool

Contains returns true if the Option is present and the given predicate returns true on the value otherwise returns false

func (Option[T]) Empty

func (o Option[T]) Empty() bool

Empty returns true if the Option has no value set

func (Option[T]) Equal

func (o Option[T]) Equal(other Option[T]) bool

Equal reports whether two fields are equal. It's implemented for testing purposes.

func (Option[T]) ForAll

func (o Option[T]) ForAll(f func(v T))

ForAll calls the given function with the value if present

func (Option[T]) ForEach

func (o Option[T]) ForEach(predicate func(v T) bool) bool

ForEach returns true if the Option is empty or the given predicate returns true on the value

func (Option[T]) Get

func (o Option[T]) Get() (val T, ok bool)

Get gets the option value and returns ok==true if present.

func (Option[T]) GetOrElse

func (o Option[T]) GetOrElse(alternative T) T

GetOrElse returns the value if present, otherwise returns the alternative value

func (Option[T]) GetOrElseF

func (o Option[T]) GetOrElseF(alternative func() T) T

GetOrElseF returns the value if present, otherwise returns the alternative value

func (Option[T]) MustGet

func (o Option[T]) MustGet() (rtn T)

MustGet returns the value if present, otherwise panics

func (Option[T]) OrElse

func (o Option[T]) OrElse(alternative T) Option[T]

OrElse returns an Option with the value if present, otherwise returns the alternative value

func (Option[T]) Present

func (o Option[T]) Present() bool

Present returns true if the Option has a value set

func (Option[T]) PtrOrNil

func (o Option[T]) PtrOrNil() *T

PtrOrNil returns the value as a pointer, if present, or nil otherwise.

func (Option[T]) String

func (o Option[T]) String() string