44 lines
1.3 KiB
JavaScript
44 lines
1.3 KiB
JavaScript
var classyGreeting = (firstName, lastName) =>
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"The name's " + lastName + ", " + firstName + " " + lastName;
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var yellGreeting = R.compose(R.toUpper, classyGreeting);
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yellGreeting("James", "Bond"); //=> "THE NAME'S BOND, JAMES BOND"
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R.compose(Math.abs, R.add(1), R.multiply(2))(-4); //=> 7
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// get :: String -> Object -> Maybe *
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var get = R.curry((propName, obj) => Maybe(obj[propName]));
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// getStateCode :: Maybe String -> Maybe String
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var 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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var db = {
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users: {
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JOE: {
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name: "Joe",
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followers: ["STEVE", "SUZY"]
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}
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}
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};
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// We'll pretend to do a db lookup which returns a promise
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var lookupUser = userId => Promise.resolve(db.users[userId]);
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var lookupFollowers = user => Promise.resolve(user.followers);
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lookupUser("JOE").then(lookupFollowers);
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// followersForUser :: String -> Promise [UserId]
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var followersForUser = R.composeP(lookupFollowers, lookupUser);
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followersForUser("JOE").then(followers => console.log("Followers:", followers));
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// Followers: ["STEVE","SUZY"]
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const mapStateToProps = state => ({
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users: R.compose( R.filter(R.propEq('status', 'active')),
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R.values)(state.users)
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});
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