Most languages have poor support for structural types though. If you try and join two records together (like a SQL join), what will your favourite language infer then?

▲ sfn42 4 hours ago | parent [-]

C# has anonymous types which is pretty much the same thing. Though I prefer to declare actual types for most usecases, I'll only use anonymous types for intermediate results and such.

▲ grumpyprole 4 hours ago | parent [-]

I certainly don't mean to knock nominal types. But I think structural types are more fundamental. A language would only need a single "newtype" or "nominal" keyword to create nominal types from structural types.

	▲	lock1 an hour ago \| parent [-]
		Why structural is more fundamental? C#'s anonymous type shares some flexibility of structural type system even though it still a nominal type. `> A language would only need a single "newtype" or "nominal" keyword to create nominal types from structural types.` I think you also can add `structural` keyword & apply structural type system in generally nominal type system as well if we're talking about adding feature.