this post was submitted on 16 Oct 2024
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What are some mind blowing Rust tricks? (programming.dev)
submitted 1 month ago* (last edited 1 month ago) by little_ferris@programming.dev to c/rust@programming.dev
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If we were to create a Rust version of this page for Haskell, what cool programming techniques would you add to it?

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[–] Buttons@programming.dev 3 points 1 month ago (1 children)

What if I specify the wrong type? let retrieved = storage.get::<SomeOtherType>();?

Is it a runtime error or a compile time error?

[–] Buttons@programming.dev 7 points 1 month ago (1 children)

To answer my own question: I believe it's a runtime error: https://doc.rust-lang.org/stable/std/any/trait.Any.html#method.downcast

[–] Ephera@lemmy.ml 2 points 1 month ago* (last edited 1 month ago)

Well, you would determine the TypeId of SomeOtherType, then search for that as the key in your HashMap and get back a None, because no entry exists and then you'd hand that back to the user.
I guess, my little usage example should've included handling of an Option value...

So, it's only a runtime error, if you decide to .unwrap() or similar.