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Something I've long wanted is a type-explainer - something that will let me highlight parts of a type definition and tell me in English what the fragment means. The example that OP linked elsewhere in this thread [0] is a good one - I know what parts of that mean, but I've never seen "T extends string = string" before.

[0] https://news.ycombinator.com/item?id=32569708

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It's just "T extends string", with a default value of `string` if you don't supply T.

And the purpose of "T extends string" is to carry the value of a string literal. For example, there's the string value "foo", but there's also a type "foo" which extends string and has only the one possible value.

That would be cool to see, actually reminds me of the cdecl explain project [1].

[1] https://cdecl.org/

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