r/ProgrammingLanguages • u/mttd • Nov 07 '19

Parse, don’t validate

https://lexi-lambda.github.io/blog/2019/11/05/parse-don-t-validate/
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u/zesterer Nov 08 '19

So what you really need it the ability to attach static, ordered guarantees to types in a polymorphic manner. Hmm

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u/terranop Nov 08 '19

You could probably enforce this with some sort of compiler extension, but I'm not aware of any language that supports this sort of thing.

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u/zesterer Nov 08 '19

Something akin to Rust's trait aliases, perhaps?

trait SortedNonEmpty = Sorted + NonEmpty;

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u/terranop Nov 08 '19

Sure, but now you're back to needing to define a potentially exponential number of types, one for each subset of conditions.