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| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 | 1x 1x 4x 1x 4x | import { alwaysTrue } from "@benneq/predicate";
import { find } from "./find";
/**
* Get the first element of an {@link Iterable}, or an optional default value
* if the {@link Iterable} is empty.
*
* Returns `undefined` if the {@link Iterable} is empty and no `defaultValue`
* was provided.
*
* @example
* Get the first element
* ```ts
* const result = first()([1,2,3]);
* console.log(result); // 1
* ```
*
* @example
* Get the first element or the `defaultValue`
* ```ts
* const result = first(1)([]);
* console.log(result); // 1
* ```
*
* @see {@link filter} and {@link find} for similar operations.
*
* @typeParam T - the {@link Iterable} value type
* @param defaultValue - the default value
* @returns the first element of the {@link Iterable}, or the defaultValue
*/
export const first: {
<T>(): (iterable: Iterable<T>) => T | undefined;
<T>(defaultValue: T): (iterable: Iterable<T>) => T;
} = <T>(defaultValue?: T): ((iterable: Iterable<T>) => T | undefined) => {
return find(alwaysTrue, defaultValue);
};
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