The Newark rapper Mach-Hommy switches between languages a lot — not just verbally, but musically, too. Consider the case of “Au Revoir,” a song that appears near the end of Mach’s new album Pray For Haiti. The production comes from DJ Green Lantern, a mixtape legend, but “Au Revoir” doesn’t sound like mixtape music. Instead, it’s hazy and drumless. A psychedelic guitar twinkles expansively. A synth drones away. A wordless half-chanted backing vocal returns again and again. A wispy flute occasionally bubbles up. The Brooklyn singer and flutist Melanie Charles sings with great longing in Haitian Creole, and Mach, half-singing himself, repeats the same phrase again and again, like a koan: “Au revoir, pussy n***as, goodbye.” It’s gooey and hypnotic, and it doesn’t sound much like rap music.