this post was submitted on 16 Oct 2024
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Rust

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submitted 1 month ago* (last edited 1 month ago) by little_ferris to c/rust
 

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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[–] [email protected] 30 points 1 month ago (3 children)

Not exactly the same thing but this is still pretty funny. This is code that is technically 100% legal Rust but you should definitely never write such code πŸ˜….

[–] AsudoxDev 12 points 1 month ago (1 children)
[–] [email protected] 23 points 1 month ago (1 children)

It's a test for the compiler which ensures that these legal yet extremely weird expressions continue to compile as the compiler is updated. So there is a purpose to the madness but it does still look pretty funny.

[–] [email protected] 8 points 1 month ago

That’s make sense. We used to write some ridiculous tests too, but users still managed to find a way


fn union() {
    union union<'union> { union: &'union union<'union>, }
}

Is my favorite.

[–] [email protected] 6 points 1 month ago* (last edited 1 month ago)

That makes complete sense. Ranges implement fmt::Debug, .. is a range, in particular the full range (all values) ..= isn't because the upper bound is missing but ..=.. ranges from the beginning to the... full range. Which doesn't make sense semantically but you can debug print it so add a couple more nested calls and you get a punch card.

I totally didn't need the Rust playground to figure that out.

EDIT: Oh, glossed over that: .. is only the full range if standing alone, it's also an infix operator which is why you can add as many as you want (be careful with whitespace, though). .. .. .. .. .. .. .. .. .. .. is a valid Rust expression.

[–] silasmariner 4 points 1 month ago

This is excellent content