Another example of a deep module is the garbage collector in a language such as Go or Java. This module has no interface at all; it works invisibly behind the scenes to reclaim unused memory. Adding garbage collection to a system actually shrinks its overall interface, since it eliminates the interface for freeing objects. The implementation of a garbage collector is quite complex, but that complexity is hidden from programmers. Deep modules such as Unix I/O and garbage collectors provide powerful abstractions because they are easy to use, yet they hide significant implementation complexity.
Deep modules , simple interface wuth lots of functionality
