if vs. when vs. and: style question

[Marcin Borkowski]

Hi there,

assuming (e1) and (e2) are some expressions, all three forms:

(if (e1) (e2))

(when (e1) (e2))

(and (e1) (e2))

are semantically equivalent.  Which one is better style (and when)?
I would guess that =when= is better iff (e2) is a =progn= (since we can
drop the =progn= altogether, and this seems to be the point of =when=),
and =and= might be considered better (well, maybe) by some people when
both (e1) and (e2) are very short (though I personally would avoid that,
since =if= seems easier for a human to understand at a first glance).
Am I right?

Notice: by “better” I mean “more idiomatic”, or “easier/faster to read
for a human”, or “more likely to be used by an experienced Elisp
hacker”, etc.

Regards,

-- 
Marcin Borkowski
http://octd.wmi.amu.edu.pl/en/Marcin_Borkowski
Faculty of Mathematics and Computer Science
Adam Mickiewicz University