Cullender

filters.js

/**
 * @typedef {function(T, number, T[]):boolean} Filter
 * @template T
 */

/**
 * @param {T} value
 * @returns {T}
 * @template T
 */
const DEFAULT_Λ = (value) => value

/**
 * @param {function(T, number, T[]):*} [λ]
 * @returns {Filter}
 * @template T
 */
export const truthy = (λ = DEFAULT_Λ) => (...args) => !!λ(...args)

/**
 * @param {string} value
 * @param {function(T, number, T[]):string} [λ]
 * @returns {Filter}
 * @template T
 */
export const includes = (value, λ = DEFAULT_Λ) => (...args) => {
  const isIncluded = λ(...args).toLowerCase().includes(value.toLowerCase())
  return isIncluded;
}

/**
 * @param {...number}
 * @returns {Filter}
 */
export const indexes = (...indexes) => (_, index) => indexes.includes(index)

index.js

/**
 * @typedef {function(T, number, T[]):boolean} Filter
 * @template T
 */

/**
 * @param {...Filter} filters
 * @returns {function(T[]):T[]}
 * @template T
 */
export const cull = (...filters) => (items) => {
  const result = filters.reduce((items, filter) => items.filter(filter), [...items])
  return result
}

/**
 * @param {...Filter} filters
 * @returns {Filter}
 */
export const merge = (...filters) => {
  const filter = (...args) => filters.every((filter) => filter(...args))
  return filter
}