Comment by tombert
1 day ago
No, it really isn’t that different. If I had a dynamic type system I would have to null check everything. If I have declare everything as a Maybe, I would have to null check everything.
For things that are invariants, that’s also trivial to check against with `if(!isValid(obj)) throw Error`.
Sure. The difference is that with a strong typing system, the compiler makes sure you write those checks. I know you know this, but that’s the confusion in this thread. For me too, I find static type systems give a lot more assurance in this way. Of course it breaks down if you assume the wrong type for the data coming in, but that’s unavoidable. At least you can contain the problem and ensure good error reports.
The point of a type system isn’t ever that you don’t have to check the things that make a value represent the type you intend to assign it. The point is to encode precisely the things that you need to be true for that assignment to succeed correctly. If everything is in fact modeled as an Option, then yes you have to check each thing for Some before accessing its value.
The type is a way to communicate (to the compiler, to other devs, to future you) that those are the expected invariants.
The check for invariants is trivial as you say. The value of types is in expressing what those invariants are in the first place.
You missed the entire point of the strong static typing.
I don’t think I did. I am one of the very few people who have had paying jobs doing Scala, Haskell, and F#. I have also had paying jobs doing Clojure and Erlang: dynamic languages commonly used for distributed apps.
I like HM type systems a lot. I’ve given talks on type systems, I was working on trying to extend type systems to deal with these particular problems in grad school. This isn’t meant to a statements on types entirely. I am arguing that most systems don’t encode for a lot of uncertainty that you find when going over the network.
With all due respect, you can use all of those languages and their type systems without recognizing their value.
For ensuring bits don't get lost, you use protocols like TCP. For ensuring they don't silently flip on you, you use ECC.
Complaining that static types don't guard you against lost packets and bit flips is missing the point.
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