Blorp by Example

Unions and Enums

Use unions for explicit states, and enums for simple named constants.

Variants

A union lists the possible shapes a value can have.

variant.brp

union Download:
    Queued
    Running(Int)

Variants With Data

A variant can carry data, such as Running(Int).

payload.brp

status: Download = Running(40)

Enums

An enum is for variants with no payload.

enum.brp

enum Direction:
    North
    South

Explicit States

Modeling states as variants prevents impossible combinations of fields.

states.brp

state: Download = Failed("network")

Example

download.brp

union Download:
	Queued
	Running(Int)
	Done(String)
	Failed(String)


pure func describe(download: Download) -> String:
	match download:
		Queued: "queued"
		Running(percent): "running " + percent.to_string()
		Done(path): "done: " + path
		Failed(msg): "failed: " + msg


func main(args: List[String]) -> Void:
	print(describe(Running(40)))

Try It

terminal

blorp run download.brp