I mean, the design doc is wrong. Instead of Object.defineProperty(HeaderImpl, "name", { value: "Header" }); you can just use export let Header = class He

I mean, the design doc is wrong. Instead of Object.defineProperty(HeaderImpl, "name", { value: "Header" }); you can just use export let Header = class Header { } to avoid creating a conflict between the header type declaration and this header implementation, since that way the type will be locally constrained to the class expression and only the variable gets out. > Who knows if this kicks Header out of some optimization path in V8 It doesn't. --- Forgive me for being suspicious of the whole thing because a couple of the rationalizations don't make sense, I'm sure there are some valid points raised there.