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0 pointstzs5y ago0 comments

I'm not so sure about that. When I'm actually using variables in expressions or as arguments to functions, as opposed to when I'm declaring them, the code is essentially the same in a typed language and in an untyped language.

Realizing when I'm writing that the expression I'm about to type is wrong because the types do not match still depends on my doing type checking in my head.

It seems to me that the case where typed wins is when my in-head type checker fails and I write something that is invalid. The typed language will catch that failure at compile time. The untyped won't catch it until runtime (and maybe not even then).

For the typed language, an IDE might be able to catch a mistake immediately so I don't have to wait until compilation to find it, and that immediate feedback might prevent me from writing dozens more lines with the same mistake, but even then I was using my in-head type checker to write that first mistake for the IDE to catch.

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valenterry5y ago

You are only describing a small part.

Here's another example. You are using a library and call a function that expects a List[Foo] as argument. Now you check in the same library if there is a function that returns a List[Foo] or at least a Foo. So you find it and are good.

Without types, now you have to read the documentation which is much much slower than having your IDE help you out. And yeah, sometimes variable names and function names are sufficient, but in my experience they are very often not.

Also, what happens when you update your library to the next version and it changed what it expects and returns? Now you either have a typechecker that checks _all_ the code, even the one you haven't written... or you have to do it yourself. For each version. And each library.

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