import { curry } from '../curry.js'
import { concat } from '../iter.js'
import { Impure, pure, impure } from './free.js'

/** @import {InferredMorphism, Morphism, ChainConstructor} from './types.js' */

/**
 * @template T
 * @param {T} x
 * @returns {x}
 */
export const id = x => x

export const compose = curry(
  /**
   * @template T, U, V
   * @param {Morphism<U, V>} f
   * @param {Morphism<T, U>} g
   * @param {T} x
   * @returns V
   */
  (f, g, x) => f(g(x))
)

export const kleisliCompose = curry(
  /**
   * @template {ChainConstructor<T>} M, T, U
   * @param {M} f
   * @param {Morphism<T, U>} g
   * @param {T} x
   * @returns U
   */
  (f, g, x) => f(x).chain(g)
)

export const lift = (...args) => args

/**
 * @template T
 * @param {T} x
 * @returns {Impure<T>}
 */
export const liftF = x => impure(
  x,
  /** @type {InferredMorphism<T>} */(pure)
)

/**
 * @param {number} a
 * @param {number} b
 * @returns {number}
 */
export const add = (a, b) => a + b

/**
 * @template T
 * @param {T} x
 * @returns {() => T}
 */
export const thunk = x => () => x

export const prepend = (x, xs) => concat([x], xs)

export const type = x => typeof x
export const is = (ctr, x) => x.constructor === ctr