[gherkinnn]

In practice I’m very happy with structural types. It provides all the safety I could wish for and slots in well with the underlying language and broader ecosystem.

Though I do miss an easy way to create something like a type Email of string, as it conforms to a set of rules. But that’s a small price to pay.

[mirekrusin]

Flow has structural typing on types and nominal on classes with correct inheritance semantics, which simply makes sense.

For making Email type distinct from string, you want opaque type (first class in flow) which you can emulate as tagged type in ts.

[gherkinnn]

Oh! Interesting. I was unaware of Flow’s details. Though I never program in an OOP style so I wouldn’t have noticed those nuances anyway.

I know of TS’ opaque types, but it always feels dirty. So here I am, relying on named params instead.