In C#, a now popular choice is record struct Foo(int Value); In F#, this is instead done with // Foo and Bar cannot be assigned to each other type Foo

In C#, a now popular choice is record struct Foo(int Value); In F#, this is instead done with // Foo and Bar cannot be assigned to each other type Foo = Foo of int type Bar = Bar of int // Foo and Bar can be assigned to each other type Foo = int type Bar = int The first variant uses single-case unions. It's a bit unfortunate that they also default to classes over structs unless you annotate them with [<Struct>], partially fixed by escape analysis though. The enum trick is the tersest and will also serialize correctly in most cases, but I have never seen anyone use it like that before.