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Last active January 12, 2024 18:30
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Pattern matching in typescript example
Raw
.ts
type LinkedList<A> = {} | { head: A; tail: LinkedList<A> };
type ToUnion<T> = T extends { head: infer N; tail: infer Tail }
? N | ToUnion<Tail>
: never;
type ToArray<T> = T extends { head: infer N; tail: infer Tail }
? [N, ...ToArray<Tail>]
: [];
type myList = { head: 1; tail: { head: 4; tail: { head: 2; tail: {} } } };
type foo = ToUnion<myList>; // 1 | 4 | 2
type bar = ToArray<myList>; // [1, 4, 2]
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