Documentation
¶
Overview ¶
o provides an Option type to represent values that may or may not be present.
This code was copies from https://github.com/BooleanCat/go-functional@ae5a155c0e997d1c5de53ea8b49109aca9c53d9f and we've added the Map function and associated tests. It was pulled into the project because I believe if we're using Option, it should be a core domain type rather than a dependency.
Index ¶
- type Option
- func (o Option[T]) Expect(message string) T
- func (o Option[T]) IsNone() bool
- func (o Option[T]) IsSome() bool
- func (o Option[T]) String() string
- func (o Option[T]) Unwrap() T
- func (o Option[T]) UnwrapOr(value T) T
- func (o Option[T]) UnwrapOrElse(f func() T) T
- func (o Option[T]) UnwrapOrZero() T
- func (o Option[T]) Value() (T, bool)
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Option ¶
type Option[T any] struct { // contains filtered or unexported fields }
Option represents an optional value. The Some variant contains a value and the None variant represents the absence of a value.
func Map ¶
Map applies a function to the contained value of (if Some), or returns None.
Use this function very sparingly as it can lead to very unidiomatic and surprising Go code. However, there are times when used judiciiously, it is significantly more ergonomic than unwrapping the Option.
Example ¶
package main
import (
"fmt"
o "github.com/cli/cli/v2/pkg/option"
)
func main() {
fmt.Println(o.Map(o.Some(2), double))
fmt.Println(o.Map(o.None[int](), double))
}
func double(i int) int {
return i * 2
}
Output: Some(4) None
func SomeIfNonZero ¶ added in v2.71.0
func SomeIfNonZero[T comparable](value T) Option[T]
func (Option[T]) Expect ¶
Expect returns the underlying value for a Some variant, or panics with the provided message for a None variant.
Example ¶
package main
import (
"fmt"
o "github.com/cli/cli/v2/pkg/option"
)
func main() {
fmt.Println(o.Some(4).Expect("oops"))
}
Output: 4
func (Option[T]) IsNone ¶
IsNone returns true if the Option is a None variant.
Example ¶
package main
import (
"fmt"
o "github.com/cli/cli/v2/pkg/option"
)
func main() {
fmt.Println(o.Some(4).IsNone())
fmt.Println(o.None[int]().IsNone())
}
Output: false true
func (Option[T]) IsSome ¶
IsSome returns true if the Option is a Some variant.
Example ¶
package main
import (
"fmt"
o "github.com/cli/cli/v2/pkg/option"
)
func main() {
fmt.Println(o.Some(4).IsSome())
fmt.Println(o.None[int]().IsSome())
}
Output: true false
func (Option[T]) String ¶
String implements the fmt.Stringer interface.
func (Option[T]) Unwrap ¶
func (o Option[T]) Unwrap() T
Unwrap returns the underlying value of a Some variant, or panics if called on a None variant.
Example ¶
package main
import (
"fmt"
o "github.com/cli/cli/v2/pkg/option"
)
func main() {
fmt.Println(o.Some(4).Unwrap())
}
Output: 4
func (Option[T]) UnwrapOr ¶
func (o Option[T]) UnwrapOr(value T) T
UnwrapOr returns the underlying value of a Some variant, or the provided value on a None variant.
Example ¶
package main
import (
"fmt"
o "github.com/cli/cli/v2/pkg/option"
)
func main() {
fmt.Println(o.Some(4).UnwrapOr(3))
fmt.Println(o.None[int]().UnwrapOr(3))
}
Output: 4 3
func (Option[T]) UnwrapOrElse ¶
func (o Option[T]) UnwrapOrElse(f func() T) T
UnwrapOrElse returns the underlying value of a Some variant, or the result of calling the provided function on a None variant.
Example ¶
package main
import (
"fmt"
o "github.com/cli/cli/v2/pkg/option"
)
func main() {
fmt.Println(o.Some(4).UnwrapOrElse(func() int {
return 3
}))
fmt.Println(o.None[int]().UnwrapOrElse(func() int {
return 3
}))
}
Output: 4 3
func (Option[T]) UnwrapOrZero ¶
func (o Option[T]) UnwrapOrZero() T
UnwrapOrZero returns the underlying value of a Some variant, or the zero value on a None variant.
Example ¶
package main
import (
"fmt"
o "github.com/cli/cli/v2/pkg/option"
)
func main() {
fmt.Println(o.Some(4).UnwrapOrZero())
fmt.Println(o.None[int]().UnwrapOrZero())
// Output
// 4
// 0
}
func (Option[T]) Value ¶
Value returns the underlying value and true for a Some variant, or the zero value and false for a None variant.
Example ¶
package main
import (
"fmt"
o "github.com/cli/cli/v2/pkg/option"
)
func main() {
value, ok := o.Some(4).Value()
fmt.Println(value)
fmt.Println(ok)
}
Output: 4 true
Source Files