Evaluator

interpreter.py

FAIL = Symbol("Fail")

def eval(code, env):
    ret = FAIL
    if isinstance(code, Call):        
        function = eval(code.call, env)
        new_env = function.bindings
        for arg in function.lambda_list:
            if arg.code:
                new_env[arg.name] = code.args[arg.name]
            else:
                new_env[arg.name] = eval(code.args[arg.name], env)

        if isinstance(function, Builtin):
            ret =function.function(new_env, env)

        elif isinstance(function, Lambda):
            for c in function.body:
                ret = eval(c, new_env)

    elif (isinstance(code, Builtin) or
          isinstance(code, Number)):
        ret = code

    elif isinstance(code, Symbol):
        ret = env[code.symbol]

    return ret