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x/ramda/composeK.js

:ram: Practical functional Javascript
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import chain from './chain';import compose from './compose';import map from './map';

/** * 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), f)`. * * @func * @memberOf R * @since v0.16.0 * @category Function * @sig Chain m => ((y -> m z), (x -> m y), ..., (a -> m b)) -> (a -> m z) * @param {...Function} ...functions The functions to compose * @return {Function} * @see R.pipeK * @deprecated since v0.26.0 * @example * * // get :: String -> Object -> Maybe * * const get = R.curry((propName, obj) => Maybe(obj[propName])) * * // getStateCode :: Maybe String -> Maybe String * const getStateCode = R.composeK( * R.compose(Maybe.of, R.toUpper), * get('state'), * get('address'), * get('user'), * ); * getStateCode({"user":{"address":{"state":"ny"}}}); //=> Maybe.Just("NY") * getStateCode({}); //=> Maybe.Nothing() * @symb R.composeK(f, g, h)(a) = R.chain(f, R.chain(g, h(a))) */export default function composeK() { if (arguments.length === 0) { throw new Error('composeK requires at least one argument'); } var init = Array.prototype.slice.call(arguments); var last = init.pop(); return compose(compose.apply(this, map(chain, init)), last);}