def _list_of_values(self, expressions, env):
if procedure.no_operands(expressions):
return EmptyList
else:
return cons(
self._eval(procedure.first_operand(expressions), env),
self._list_of_values(procedure.rest_operands(expressions), env))
def _eval_and(self, expr, env):
if procedure.no_operands(procedure.operands(expr)):
return Boolean(True)
def inner(expr, env):
if sequence.is_last_expr(expr):
return self._eval(sequence.first_expr(expr), env)
if not self._eval(sequence.first_expr(expr), env):
return Boolean(False)
return inner(sequence.rest_exprs(expr), env)
return inner(sequence.rest_exprs(expr), env)
def _eval_or(self, expr, env):
if procedure.no_operands(procedure.operands(expr)):
return Boolean(False)
def inner(expr, env):
if sequence.is_last_expr(expr):
return self._eval(sequence.first_expr(expr), env)
first_value = self._eval(sequence.first_expr(expr), env)
if first_value:
return first_value
return inner(sequence.rest_exprs(expr), env)
return inner(sequence.rest_exprs(expr), env)