Generics can be used without being declared in type definitions:

[Tatskaari]

For example:

type option :=
    Some of a,
    None
    
val b := Some(10)

val Some(value) := b

output value

It would be good to allow generics in types using the following syntax:

type a option :=
    Some of a,
    None
    
val b : integer option := Some(10)

val Some(value : integer) := b

output value

[Tatskaari]

I can't see anything immediately wrong with allowing generics that haven't specifically been declared however it's not very useful and is probably indicative of a programmer error. This should be picked up in the type checker.