IMO The problem as it stands now is that when developing typescript you have a compiler running on your machine doing the typechecking. It will error out and simply not compile when you try to pass a string to a fn expecting a number.
What if there is a bug (or even a misconfiguration in your project)? Or typescript changes over time (and now there are different versions all needed to be supported)? Or what if the types from typescript (designed for programmers) are not always inline with V8 internal representation of objects?) Or what if people push typescript through V8 with compile time errors? (The compiler should have prevented this from happening - but you can pump whatever you want into V8, including things considered broken by typescript).
You only really get any improvement in runtime if your compiler guarantees anything (and bakes it into whatever it is compiling). As of now there are little guarantees with the javascript language (which is what comes out of your typescript compiler). AFAIK typescript is designed to help programmers find common bugs.
Not saying it's not possible, but more work is needed into bridging the two.
What if there is a bug (or even a misconfiguration in your project)? Or typescript changes over time (and now there are different versions all needed to be supported)? Or what if the types from typescript (designed for programmers) are not always inline with V8 internal representation of objects?) Or what if people push typescript through V8 with compile time errors? (The compiler should have prevented this from happening - but you can pump whatever you want into V8, including things considered broken by typescript).
You only really get any improvement in runtime if your compiler guarantees anything (and bakes it into whatever it is compiling). As of now there are little guarantees with the javascript language (which is what comes out of your typescript compiler). AFAIK typescript is designed to help programmers find common bugs.
Not saying it's not possible, but more work is needed into bridging the two.