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Comment by planede

It seems to be stem from `Record` being contravariant in its Key type, right?

  const taskCounts = { work: 10, home: 5, personal: 3 };

This probably has the deduced type of `Record<"work" | "home" | "personal", number>`.

I wonder if there is a hole in the type system that could be filled with an `ExactKeyTypeRecord<K, V>`, which is invariant in K and is a subtype of `Record<K, V>`. Maybe this could have Object.keys() defined as expected.

I have no experience with TS, but I believe Python's TypedDict has a bunch of similar holes in the type system that could be mitigated with a bit more elaborate type hierarchies.

parent planede 3 years ago

Comment by planede

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