Comment by tybug

16 days ago

Yep, `#[derive(DefaultGenerator)]` and `generators::default<T>()` are the right tools here.

This is one of the areas we've dogfooded the least, so we'd definitely be happy to get feedback on any sharp corners here!

I think `from_type` is one of Hypothesis's most powerful and ergonomic strategies, and that while we probably can't get quite to that level in rust, we can still get something that's pretty great.

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tybug

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DRMacIver  16 days ago

What do you think we're currently missing that Python's `from_type` has? I actually think the auto-deriving stuff we currently have in Rust is as good or better than from_type (e.g. it gets you the builder methods, has support for enums), but I've never been a heavy from_type user.

  • tybug  16 days ago

    `from_type` just supports a bunch more things than rust ever can due to the flexibility of python's type system. `from_type(object)` is amazing, for example, and not something we can write in rust.

    • DRMacIver  16 days ago

      Yeah, that's true. I was going to say that it's maybe not fair to count things that just don't even make sense in Rust, but I guess the logical analogue is something like `Box<dyn MyTrait>` which it would make sense to have a default generator for but also we're totally not going to support that.

sunshowers  16 days ago

Thank you! I have some particularly annoying proptest-based tests that I'll try porting over to Hegel soon. (Thanks for writing the Claude skill to do this.)

  • DRMacIver  16 days ago

    Please let us know how it goes!

    As Liam says, the derive generator is not very well dogfooded at present. The claude skill is a bit better, but we've only been through a few iterations of using it and getting Claude to improve it, and porting from proptest is one of the less well tested areas (because we don't use proptest much ourselves).

    I expect all of this works, but I'd like to know ways that it works less well than it could. Or, you know, to bask in the glow of praise of it working perfectly if that turns out to be an option.