Decrease Unit implementation runtime size #360
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Make it a prototype-less object which is *cast* as `Unit`. This means that it has an even smaller overhead at runtime than it did before, and it basically acts like an empty object in the type system... but one with a useful name, and a guarantee that there is only ever one of it.
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Make it a prototype-less object which is cast as
Unit. This means that it has an even smaller overhead at runtime than it did before, and it basically acts like an empty object in the type system... but one with a useful name, and a guarantee that there is only ever one of it.All the type test changes here indicate that this is a wider type, usable in more places than previously. Since it was impossible to perform an actual brand check before in a way that surfaced in the type system, this is safe. (From a runtime POV, users could have been distinguishing it by using
Object.getOwnPropertySymbols()but 🤷🏼♂️)