What is the difference among the functions doall dorun doseq and for?

dorun, doall, and doseq are all for forcing lazy sequences, presumably to get side effects.

• dorun – don’t hold whole seq in memory while forcing, return nil
• doall – hold whole seq in memory while forcing (i.e. all of it) and return the seq
• doseq – same as dorun, but gives you chance to do something with each element as it’s forced; returns nil

for is different in that it’s a list comprehension, and isn’t related to forcing effects. doseq and for have the same binding syntax, which may be a source of confusion, but doseq always returns nil, and for returns a lazy seq.