I can't answer about prozac and adderall specifically but it can go two ways. With some drugs it decreases their effectiveness. With other drugs it can cause overdose. Either way, it's not a good thing. Also, alcohol is a depressant so it will make depression worse.
It's not a good idea to mix alcohol with medication. If it is an occasional drink I don't think it will do any harm. Making you feel sick is the worst. However, I would not advise regular intake of alcohol.
Mixing alcohol with any medication is questionable, depending on the medication in question. Alcohol and psychiatric medication should never be mixed, Besides alcohol being a depressant and directly affecting your mood, mixing them together can depending on the medication be down right dangerous.
On how it specifically effects Prozac and adderall ? It will obviously not only counteract any benefit you might be gaining from your antidepressant but it will directly affect how much adderall is absorbed and how much is left for your body to use. I assume that this is prescribed to you for a diagnosed condition. If so, you are not helping yourself with taking these above medications with alcohol, if we are speaking about a glass of wine or a beer
it's not the greatest choice but not all is lost.
If you speaking about drinking frequently then you are not only not helping yourself but you are putting your mental and physical health in danger.
Please don't do that to yourself, surely your aim for taking medication is to get well, not the exact opposite.