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duarten/meta-unique.ts

Last active September 19, 2020 05:44
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Tuple type containing only unique values
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meta-unique.ts
type ElementOf<T> = T extends (infer E)[] ? E : never;
type TupleHead<Tuple extends readonly unknown[]> =
Tuple extends [infer HeadElement, ...readonly unknown[]] ? HeadElement : never;
type TupleTail<Tuple extends readonly unknown[]> =
Tuple extends [unknown, ...infer TailElements] ? TailElements : never;
type Unique<Tuple extends readonly unknown[]>
= Tuple extends []
? []
: (TupleHead<Tuple> extends ElementOf<TupleTail<Tuple>>
? never
: [TupleHead<Tuple>, ...Unique<TupleTail<Tuple>>])
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