Uses of the type Unit

Question

The Unit type is a singleton type containing the constant unit. In functional languages with side effects, unit is used in functions that perform side effects. For example print is a function from string to Unit.

Unit also corresponds to truth. If you view the type of the expression as a proposition and the program as a proof, Unit corresponds to truth since you can always prove Unit by using the constant unit.

My question is aside from these two uses, is there any other uses of Unit?