Crosscut

There's an important topic related to structural typing that I haven't talked about so far: normalizing structural types. Let's consider a function that takes a record { a: A, b: B }. What if the user provides a record { b: B, a: A } to that function?

I think it should just work. Those two records should be considered the same type. Which means, before comparing them, the records need to be normalized, by sorting their fields. Probably alphabetically, by field name. But that might be an internal implementation detail.

And unless I'm missing something, that's all there is to say about normalizing record types. But normalization is a bit more interesting with variant types, so let's get into that tomorrow!