In a large mixing bowl, combine the yogurt, mayonnaise, lime juice, and turmeric and curry powder. Season with salt, and stir in the coconut. Let the mixture sit for about 30 minutes to blend the flavors.
Meanwhile, shred the cabbage. Add the cabbage, pineapple, green onions, and cilantro, if using, to the coconut mixture and toss gently. Taste and adjust the seasonings, then serve.