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chuckadams/singleton.ts

Created May 21, 2020 17:44
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dependent types in typescript
Raw
singleton.ts
type Maybe<a> = { val: a, tag = "some" } | { tag: "none" }
function isSome<A, Ma: Maybe<a>>(m: Ma): Ma["val"] is A {
return m.tag == "some";
}
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