Interpreter 2: Scope

scheme.py

class Procedure:
    def __init__(self, parameters, expressions, env):
        self.parameters = parameters
        self.expressions = expressions
        self.env = env   # PROCEDURE MUST REMEMBER THE ENVIRONMENT AT THE TIME THAT IT WAS DEFINED

    def __call__(self, *args):
        # Args are the argument values
        # Make a new scope for the local variables
        local_env = {}

        # Bind the parameter names to values
        for name, value in zip(self.parameters, args):
            local_env[name] = value

        for expression in self.expressions:
            result = seval(expression, {**self.env, **local_env})
        return result