How do classes differ from modules? Why might it be useful to have modules and classes in the same language? Why does the use of dynamic scoping imply the need for run-time type checking? Explain the...

How do classes differ from modules? Why might it be useful to have modules and classes in the same language? Why does the use of dynamic scoping imply the need for run-time type checking? Explain the purpose of a compiler’s symbol table. What are aliases? Why are they considered a problem in language design and implementation?