44 lines
1.4 KiB
JavaScript
44 lines
1.4 KiB
JavaScript
import chain from "./chain.js";
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import compose from "./compose.js";
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import map from "./map.js";
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/**
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* Returns the right-to-left Kleisli composition of the provided functions,
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* each of which must return a value of a type supported by [`chain`](#chain).
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*
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* `R.composeK(h, g, f)` is equivalent to `R.compose(R.chain(h), R.chain(g), f)`.
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*
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* @func
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* @memberOf R
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* @since v0.16.0
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* @category Function
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* @sig Chain m => ((y -> m z), (x -> m y), ..., (a -> m b)) -> (a -> m z)
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* @param {...Function} ...functions The functions to compose
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* @return {Function}
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* @see R.pipeK
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* @deprecated since v0.26.0
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* @example
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*
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* // get :: String -> Object -> Maybe *
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* const get = R.curry((propName, obj) => Maybe(obj[propName]))
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*
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* // getStateCode :: Maybe String -> Maybe String
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* const getStateCode = R.composeK(
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* R.compose(Maybe.of, R.toUpper),
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* get('state'),
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* get('address'),
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* get('user'),
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* );
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* getStateCode({"user":{"address":{"state":"ny"}}}); //=> Maybe.Just("NY")
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* getStateCode({}); //=> Maybe.Nothing()
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* @symb R.composeK(f, g, h)(a) = R.chain(f, R.chain(g, h(a)))
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*/
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export default function composeK() {
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if (arguments.length === 0) {
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throw new Error('composeK requires at least one argument');
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}
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var init = Array.prototype.slice.call(arguments);
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var last = init.pop();
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return compose(compose.apply(this, map(chain, init)), last);
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} |