Explain the importance of information hiding. What is an opaque export? Why might it be useful to distinguish between the header and the body of a module? What does it mean for a scope to be closed?...

Explain the importance of information hiding. What is an opaque export? Why might it be useful to distinguish between the header and the body of a module? What does it mean for a scope to be closed? Explain the distinction between “modules as managers” and “modules as types.”