sumtype-go

sumtype-go

Introduction

sumtype-go is a CLI tool designed to facilitate the creation and management of sum types (aka union types) in Go. This tool simplifies the process of generating boilerplate code for discriminated union types, making it easier to work with its variants in Go.

Quick Tour

To define this sum type:

type User
    = Anonymous
    | Member String Time
    | Admin String

write this Go type definition, e.g. in declaration.go

type User interface {
	Switch(s UserScenarios)
}

type UserScenarios struct { // be sure to suffix the name with `Scenarios`
	Anonymous func()
	Member    func(email string, since time.Time)
	Admin     func(email string)
}

Execute this command

go install github.com/choonkeat/sumtype-go@v0.2.0
sumtype-go -input declaration.go

To generate declaration.boilerplate.go and start using like

func main() {
	user1 := Anonymous()
	user2 := Member("Alice", time.Now())
	user3 := Admin("Bob")

	log.Println(
		"\nUser1:", UserString(user1),
		"\nUser2:", UserString(user2),
		"\nUser3:", UserString(user3),
	)
}

func UserString(u User) string {
	var result string
	u.Switch(UserScenarios{
		Anonymous: func() {
			result = "Anonymous coward"
		},
		Member: func(email string, since time.Time) {
			result = email + " (member since " + since.String() + ")"
		},
		Admin: func(email string) {
			result = email + " (admin)"
		},
	})
	return result
}

Refer to example/

Installation

To install sumtype-go, ensure you have Go installed on your system, and then run the following command:

go install github.com/choonkeat/sumtype-go@v0.2.0

Usage

After installation, you can start using `sumtype-go`` by invoking it from the command line. Here's a basic example of how to use it:

  -input string
    	Input file name
  -suffix string
    	Suffix of the struct name (default "Scenarios")
  -switch string
    	Name of the switch method (default "Switch")