Defining Symbols

2023-07-21

The latest feature that I implemented in my math language is the ability to define a symbol and store a value in that symbol. To implement this, I first needed to define a scope. To do this, I made the evaluate() function take in a scope as a parameter for every node. In this case, a scope is simply a map of strings to values. I also had to create a special type of node: a SymbolExpressionNode. A SymbolExpressionNode has a name, and when evaluate() is called on a SymbolsExpressionNode, it returns the value corresponding its name in the scope map. With a working scope, I could now define symbols within that scope. Whenever the interpreter came across def, it would add the next two parameters as a key and value respectively to the scope map. For example, def A 5 would add the key value pair (A,5) to the scope map. This way I can pass in the updated scope map to every evaluate() call, and it will evaluate A to 5.