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by randomdata 1026 days ago
Doesn’t seem like that big of a deal. You’re going to have a really hard time getting your first test to pass if you make a mistake.

I don’t mean using testing as a poor man’s type system, I mean even the tests you would write in a statically typed language will quickly uncover any mistakes you could possibly make there.
1 comments
KptMarchewa 1025 days ago
In statically typed systems, this wouldn't even compile.

I'm pretty sure I'd see multiple cases where the function would return different types depending on a code path.

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randomdata 1024 days ago
> In statically typed systems, this wouldn't even compile.

Still, it's not like you're going to miss that a function doesn't return something expected. Even in statically typed languages you are going to have tests to validate that much.

> I'm pretty sure I'd see multiple cases where the function would return different types depending on a code path.

That's another problem entirely. Although even then it would be pretty hard for an errant type to not blow up your tests. Again, not tests specifically meant to check that your types or sane, just the same tests you would write in a statically typed language.

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dragonwriter 1025 days ago
> I'm pretty sure I'd see multiple cases where the function would return different types depending on a code path.

Quite commonly by design, or, “why union (and sum) types are a thing”.

Something returning type “Foo | nil” is very often going to return Foo on one branch and nil on another.

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