Yes, Modafinil is good and excellent for any hacking/coding short term memory requirements. Consult doctor first, natural sleep is always best.

AVOID :: Speed, coke, crystal meth . They all make you irritable and have all the usual downsides like:

:: Prison, overdosing, tainted supply, instant loss of job, addiction, loss of self respect, suicidal impulses.

:: Some last far too long (pure speed, Meth) and others too short (Cocaine). People who take those types of drugs (truckers, air-force pilots) have bounded scenarios and repeatable experiences.