45 lines
1.4 KiB
JavaScript
45 lines
1.4 KiB
JavaScript
|
import pipeP from "./pipeP.js";
|
||
|
|
import reverse from "./reverse.js";
|
||
|
|
/**
|
||
|
|
* Performs right-to-left composition of one or more Promise-returning
|
||
|
|
* functions. The last arguments may have any arity; the remaining
|
||
|
|
* arguments must be unary.
|
||
|
|
*
|
||
|
|
* @func
|
||
|
|
* @memberOf R
|
||
|
|
* @since v0.10.0
|
||
|
|
* @category Function
|
||
|
|
* @sig ((y -> Promise z), (x -> Promise y), ..., (a -> Promise b)) -> (a -> Promise z)
|
||
|
|
* @param {...Function} functions The functions to compose
|
||
|
|
* @return {Function}
|
||
|
|
* @see R.pipeP
|
||
|
|
* @deprecated since v0.26.0
|
||
|
|
* @example
|
||
|
|
*
|
||
|
|
* const db = {
|
||
|
|
* users: {
|
||
|
|
* JOE: {
|
||
|
|
* name: 'Joe',
|
||
|
|
* followers: ['STEVE', 'SUZY']
|
||
|
|
* }
|
||
|
|
* }
|
||
|
|
* }
|
||
|
|
*
|
||
|
|
* // We'll pretend to do a db lookup which returns a promise
|
||
|
|
* const lookupUser = (userId) => Promise.resolve(db.users[userId])
|
||
|
|
* const lookupFollowers = (user) => Promise.resolve(user.followers)
|
||
|
|
* lookupUser('JOE').then(lookupFollowers)
|
||
|
|
*
|
||
|
|
* // followersForUser :: String -> Promise [UserId]
|
||
|
|
* const followersForUser = R.composeP(lookupFollowers, lookupUser);
|
||
|
|
* followersForUser('JOE').then(followers => console.log('Followers:', followers))
|
||
|
|
* // Followers: ["STEVE","SUZY"]
|
||
|
|
*/
|
||
|
|
|
||
|
|
export default function composeP() {
|
||
|
|
if (arguments.length === 0) {
|
||
|
|
throw new Error('composeP requires at least one argument');
|
||
|
|
}
|
||
|
|
|
||
|
|
return pipeP.apply(this, reverse(arguments));
|
||
|
|
}
|