README
¶
Option Type for Go
The Option package provides an Option type that represents encapsulation of an optional value; a value that may either contain a value (Some) or not contain a value (None), similar to Option in Rust.
Features
- Some: Create an
Optionthat contains a value. - None: Create an
Optionthat represents no value. - Ok: Return the value if it exists.
- Cause: Return the cause of
Noneif it is due to an error. - Process: Transform the
Optionvalue with a function that might fail. - Map: Transform the
Optionvalue with a function that cannot fail. - Flatten: Nested
Optionvalues into a singleOption. - Wrap: Wraps a value and an error into an
Option. - WrapFn: Wraps a function that returns a value and an error into a function that returns an
Option.
Installation
To use the Option package in your Go project, place the package in your project directory or a suitable location in your GOPATH. Import it using:
go get -u github.com/AY7295/go-option
Usage Examples
Here are some basic examples of how to use the Option type:
Creating Some and None
opt1 := option.Some(10)
opt2 := option.None[int]()
Processing an Option
opt := option.Some(5)
result := option.Process(opt, func(v int) (int, error) {
if v == 0 {
return 0, errors.New("zero value")
}
return 2 * v, nil
})
Mapping over an Option
opt := option.Some(10)
mapped := option.Map(opt, func(v int) int {
return v + 1
})
Flattening an Option
doubleWrapped := option.Some(option.Some(20))
flattened := option.Flatten(doubleWrapped)
Testing
To run the tests for the Option package, navigate to the package directory and execute:
go test
This will run all the tests defined in option_test.go.
Documentation
¶
Overview ¶
Package option provides a generic implementation of the Option type, similar to Rust's Option type. It is used to encapsulate an optional value: a value that may either contain a value of type T or may be empty.
Index ¶
- Variables
- func IsNone[T any](opt Option[T]) bool
- func IsSome[T any](opt Option[T]) bool
- func SetJsonCoder(coder JsonCoder)
- func WrapFn[T any](fn func() (T, error)) func() Option[T]
- type JsonCoder
- type Option
- func Flatten[T any](opt Option[Option[T]]) Option[T]
- func Map[T, U any](opt Option[T], fn func(T) U) Option[U]
- func None[T any](causes ...error) Option[T]
- func Process[T, U any](opt Option[T], fn func(T) (U, error)) Option[U]
- func Some[T any](t T) Option[T]
- func Wrap[T any](val T, errs ...error) Option[T]
Constants ¶
This section is empty.
Variables ¶
var (
Nil = errors.New("nil value")
)
Nil is a pre-defined error to represent a nil value being incorrectly used to create an Option.
Functions ¶
func IsNone ¶ added in v1.0.1
IsNone returns true if the option does not hold a value (i.e., cause is not nil).
func SetJsonCoder ¶ added in v1.1.2
func SetJsonCoder(coder JsonCoder)
Types ¶
type Option ¶
type Option[T any] interface { Cause() error // Cause returns an error if the option is none due to an error. Ok() T // Ok returns the value if present, otherwise a zero value. }
Option is a generic interface that defines methods for handling optional values.
func Flatten ¶
Flatten converts an Option[Option[T]] into a single Option[T]. If the outer Option is none, it returns a none Option with the same error; otherwise, it returns the inner Option.
func Map ¶
Map applies a function to the value within the Option, returning a new Option with the result. If the original Option is none, the function is not executed and a new none Option with the original error is returned.
func None ¶
None creates an Option that contains no value but an error. If no specific error is provided, it defaults to using Nil.
func Process ¶
Process applies a function to the value within the Option, returning a new Option with the result. If the original Option is none, the function is not executed and a new none Option with the original error is returned.
Source Files