Only after you have tried to call the function with an array many times, that's when it would make sense. And there's another option too, to instead add a check

Only after you have tried to call the function with an array many times, that's when it would make sense. And there's another option too, to instead add a check and a friendly error. But it should be a fairly rare thing to do. Naming things can be hard and maybe more so if you do not have type annotations. But being used to dynamic languages I always find type annotations a chore. And I think it's better to have a good name and no types, then a bad name and types. eg. max(...numbers) vs x(y:number, z:number) -> number . Even though x is more verbose it can be anything, but with max(...numbers) I can be fairly sure.