Comment by knubie | Hacker News Reader

Comment by knubie | Hacker News Reader

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> Even typos like `object.detail.name` vs `object.details.name` cause runtime errors, or calling a function with the wrong number of arguments or in the wrong order, some of the most trivial bugs you can think of.

In Clojure, a dynamically typed language, referencing a var that is not declared, or calling a function with the wrong number of arguments will result in a compilation error. You don't need static typing or type annotations for this.

> I don't understand how someone can dislike writing type annotations so much that they're happy having their time wasted like this when automated assistance is right there. To me, it's like not wanting to use a spellchecker when writing an article, or opting out of syntax checking code before it's ran.

It's not about liking or disliking, it's about "wasting time." Spell checking and syntax checking are free, annotating everything with types and maintaining them is not.

> In Clojure, a dynamically typed language, referencing a var that is not declared, or calling a function with the wrong number of arguments will result in a compilation error. You don't need static typing or type annotations for this.

Can it catch problems like e.g. if you try to access a `y` field on some input object but only field `x` is defined? And if you want to define a function that takes a callback that must accept two arguments? What about ways to force you to check a variable with type `string | undefined` is defined before you do something with it? At some point it must breakdown because more complex checks can't be inferred?

> it's about "wasting time." ... annotating everything with types and maintaining them is not.

See this example. I'd argue the type annotations are minimal, but you gain a lot of safety, documentation and refactoring help from them: https://github.com/hotwired/turbo/pull/971/files

The arity check in clojure sounds like a nice balance between runtime and compile time errors.

Having runtime errors is the point - that's real dynamic typing for you. If not for the possibility of runtime errors, you'd have to do more to have the code run. A lot of junior devs who prefer static typing don't get it. Senior devs who prefer static typing at least understand that some have a different preference. Of course you don't want a lot of runtime errors to make it to production, but in development, yes.

There are those who think that the IDE should provide feedback at every keystroke. Most IDEs have this opinion built into them. But I don't like it very much. It's gotten to the point where there isn't an IDE I really like. I miss Atom.

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