Subtyping -- examples
type any = { }
type entity = { age : int }
type vehicle = { age : int, speed : int }
type machine = { age : int, fuel : string }
type car = { age : int, speed : int, fuel : string }
Subtyping rules
- record = finite association of values to labels
- (a = 3, b = true ).a ≡ 3