All files / array/operator distinctBy.ts

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import {Dictionary, KeyProjection} from 'fnxt/fnxt-types';
 
export const distinctBy = <E>(projection: KeyProjection<E>) => (array: E[]): E[] => {
  const set: Dictionary<E> = {};
  for (const e of array) {
    const key = projection(e);
    if (set[key] === undefined) {
      set[key] = e;
    }
  }
  return Object.values(set);
 
};