Another important feature of ML is abstract data types (opaque signature ascription), which forces abstraction clients not to rely on implementation details. It

Another important feature of ML is abstract data types (opaque signature ascription), which forces abstraction clients not to rely on implementation details. It's Dijkstra's “separation of concerns”, integrated into the type checking process! See: https://existentialtype.wordpress.com/2011/04/16/modules-matter-most/ https://existentialtype.wordpress.com/2011/04/16/modules-mat...