Opt

Opt is a Go package for safe abstractions over optional values.

Inspired by the Option type in Rust and follows the same ideas and function signatures.

Features

Represent explicitly set values. For example: {"b":2,"a":null} and {"b":2} would be different states for a - explicit and implicit None.
All the encoding and decoding functionality: json, gob, sql, text & binary.
Adapters to construct options from pointers, zero values, and proto messages.
No reflection.

Install

go get github.com/metafates/opt

Usage

See example_test.go for more examples.

package main

import (
	"fmt"
	"time"

	"github.com/metafates/opt"
)

type User struct {
	Birth opt.Opt[time.Time]
}

func (u User) Age() opt.Opt[int] {
	return opt.Map(u.Birth, func(t time.Time) int {
		return time.Now().Year() - t.Year()
	})
}

func isAdult(age int) bool {
	return age >= 18
}

func getUser(id int) opt.Opt[User] {
	// ...
}

func main() {
	if opt.AndThen(getUser(42), User.Age).IsSomeAnd(isAdult) {
		fmt.Println("🍺!")
	}
}