Not really, and correct me if I'm wrong but afaik TS doesn't actually do row polymorphism so much as structural subtyping - although the difference between the two is pretty small and you can get pretty close to row polymorphism with structural subtyping + generics.

But even if these were the same thing and we want to be a bit pendantic since this is HN after all, structural type systems often support some kind of subtyping or row polymorphism, but it's not a strict requirement for a type system to be "structural". You could have a structural type system that doesn't allow

  { a: int, b: int } 

to be used where

  { a: int } 

is expected. How practical such a type system would be... I don't know. Flow type checker for JavaScript makes a distinction between "exact" types, i.e. object must have exactly the properties listed and no more, and "inexact" types where such subtyping is allowed.