function foo<T>(x: T & {field: number}): T { return x; } function bar<T>(x: T & {field: number}): T { const x0 = foo(x); //

function foo<T>(x: T & {field: number}): T { return x; } function bar<T>(x: T & {field: number}): T { const x0 = foo(x); // type error because x0 doesn't have field // would compile fine with row types const x1 = foo(x0); return x1; } Yes it's true. I also sorely miss the lack of row types in Haskell (I miss them even in something like Idris where you can create them more easily, but it's still not great compared to first-class support). EDIT: I may be being dumb. You could probably fix this by adding an intersection type again on the right-hand side. I think there was something else I was missing from TS, but I'll have to noodle on it a bit more.