Since cutting his teeth in Vampire Weekend, multi-instrumentalist and producer Rostam has continued spinning alt-pop and indie electronic sounds into musical gold for artists including HAIM, Clairo, and Charli XCX. His soft experimental flourishes accentuate a singer’s charm, like the throbbing disco beats shot through Carly Rae Jepsen’s sugary flirtations (“Warm Blood”) and the woozy guitar slipped into Frank Ocean’s bittersweet laments (“Ivy”).