Scala: Concatenate Lists of Strings with mkString

mkstrconcat.scala

// A list of strings into a single string
val food = "rice" :: "cookies" :: "watermelon" :: Nil
food.foldLeft("")(_ + ", " + _)
// But we would have to remove the first two chars:
// ", rice, cookies, watermelon"

// Now with mkString
val fruits = "apple" :: "orange" :: "kiwi" :: Nil
fruits mkString ", "

// If each element could be an option we need to flatten
val animals = None :: Some("monkey") :: Some("koala") :: Nil
animals.flatten mkstring ", "

// It's possible to filter for empty lists
val clothes = "trousers" :: "hat" :: "" :: "shirt" :: Nil
clothes filter {_.nonEmpty} mkString ", "