Enum types

[vtereshkov]

Having enum types would allow for stronger type checking.

Before:

// th.um
type Platform* = int
const (
	PlatformUnknown* = 0
	PlatformLinux*
	PlatformWindows*
	PlatformMacOs*
	PlatformWeb*
)

// main.um
import "th.um"

fn foo(p: th.Platform) {}

fn main() {
	foo(th.Platform.Linux) // OK
	foo(th.white)          // OK
}

After:

// th.um
type Platform* = enum {  // With optional base type, such as enum(int) or enum(uint8)
	Unknown
	Linux
	Windows
	MacOs
	Web
}

// main.um
import "th.um"

fn foo(p: th.Platform) {}

fn main() {
	foo(th.Platform.Linux) // OK
	foo(th.white)          // Error
}

[ske2004]

I still think this might be extra, I do this to enforce type checking.

type Platform = int;
const (
	Unknown = Platform(0)
	Linux = Platform(1)
	Windows = Platform(2)
	MacOs = Platform(3)
	Web = Platform(4)
)

fn foo(p: Platform) {}

fn main() {
	foo(Linux)    // OK
	foo(th.white) // Error
}

The only difference here is that the enum isn't finite, so anyone can construct it, however it can be prevented if the type is private and all in one module.

[vtereshkov]

@skejeton I get no error in this case:

type Color = int
const (
	white* = Color(255)
)

type Platform = int
const (
	Unknown* = Platform(0)
	Linux* = Platform(1)
	Windows* = Platform(2)
	MacOs* = Platform(3)
	Web* = Platform(4)
)

fn foo(p: Platform) {
        printf("%v\n", p)
}

fn main() {
	foo(Linux) // 1
	foo(white) // 255
}

[ske2004]

Huh that's strange, I almost swear I checked that, since I used it in my now deleted UI rewrite: https://github.com/skejeton/save-game/blob/89a80cda6ef77c0ac87f45d582b9034b6d233b55/src/d_ui.um#L91 Maybe it's a good idea to make the type conversions strict?