Due April 5, 1999 before class

This is a warm-up assignment to make sure everybody is up to speed with Java and to introduce a baby interpreter. We will write an interpreter for arithmetic expressions:

Exp ::= Int | Exp + Exp | Exp - Exp | Exp * Exp | Exp / Exp

I don't care about parsing in this class, so don't waste your time writing a parser. Here what I want you to do:

Represent each kind of arithmetic expression using a Java object. So for example, the expression (3+(5+6)) would be created by writing:
```
new AddExp(new IntExp(3), new AddExp(new IntExp(5), new IntExp(6)))
```
In a complete interpreter, the conversion from the textual representation of expressions to Java objects is done by the parser.
Write an evaluator that takes an expression like above and returns its value or throws an exception if you attempt to divide by zero.

Think hard about the design of the interpreter. Try to write the most elegant solution you can think of. Explain your design!

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sabry@cs.uoregon.edu