composeK.js•1.27 kB
var chain = require('./chain');
var compose = require('./compose');
var identity = require('./identity');
var map = require('./map');
var prepend = require('./prepend');
/**
* Returns the right-to-left Kleisli composition of the provided functions,
* each of which must return a value of a type supported by [`chain`](#chain).
*
* `R.composeK(h, g, f)` is equivalent to `R.compose(R.chain(h), R.chain(g), R.chain(f))`.
*
* @func
* @memberOf R
* @since v0.16.0
* @category Function
* @sig Chain m => ((y -> m z), (x -> m y), ..., (a -> m b)) -> (m a -> m z)
* @param {...Function}
* @return {Function}
* @see R.pipeK
* @example
*
* // parseJson :: String -> Maybe *
* // get :: String -> Object -> Maybe *
*
* // getStateCode :: Maybe String -> Maybe String
* var getStateCode = R.composeK(
* R.compose(Maybe.of, R.toUpper),
* get('state'),
* get('address'),
* get('user'),
* parseJson
* );
*
* getStateCode(Maybe.of('{"user":{"address":{"state":"ny"}}}'));
* //=> Just('NY')
* getStateCode(Maybe.of('[Invalid JSON]'));
* //=> Nothing()
*/
module.exports = function composeK() {
return compose.apply(this, prepend(identity, map(chain, arguments)));
};