Comment by omneity
11 days ago
I don't systematically pick one or the other location for these guards, but wouldn't it make more sense to have it in one place, the function itself, both for DRY and to ensure it being checked, rather than on every call site?
Such a requirement "oh yeah always guard your arguments for calls against this function for the "same" thing your compiler is doing anyway" shouldn't be implicit and duplicated everywhere if it's always meant to be fulfilled.
I think I take the attitude that you parse/validate data as soon as possible (ie when reading a file/coming from an API), so that the rest of the code can rely on typechecks alone.
That said, I come from a background where the language doesn't let you consider that the type of a value might be wrong (Haskell, for example), so perhaps I have more trust than typescript deserves.