Type alias narrow<input, pattern>

P.narrow<Input, Pattern> will narrow the input type to only keep the set of values that are compatible with the provided pattern type.

Read the documentation for P.narrow on GitHub

Example

type Input = ['a' | 'b' | 'c', 'a' | 'b' | 'c']
const Pattern = ['a', P.union('a', 'b')] as const

type Narrowed = P.narrow<Input, typeof Pattern>
//     ^? ['a', 'a' | 'b']
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