To me it feels like less of a hack if I can make the type declaration not a lie.... | Hacker News

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TOGoS 19 days ago | parent | context | favorite | on: What would it take to add refinement types to Rust...

To me it feels like less of a hack if I can make the type declaration not a lie. e.g.

   type FooID = string & { typeName? : "FooID" }

Read as 'of course this thing doesn't have a typeName[1] property, since it's a string, but if it did have the property, the value would be "FooID"'. You can then cast between FooID and string, but not between FooID and some other type that declares a typeName property.

[1] I actually tend to use 'classRef' with an RDFish long name for the type, but that makes examples longer and isn't the point.

Waterluvian 18 days ago [–]

That’s a really helpful way of framing it. I’m tempted to try this with our uuid type and see how well it works.

I think I’ll also try to base it on a template string too if that’s possible. Given we use a standard dash segmented uuid string.

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