This run-control file can be viewed as an imperative
minilanguage. There is an implied flow of execution: cycle through
the list of poll commands repeatedly (sleeping for a while at the end
of each cycle), and for each site entry collect mail for each
associated user in sequence. It is far from being general-purpose;
all it can do is sequence the program's polling behavior.
As with
pic(1),
one could choose to view this minilanguage as either declarations or a
very weak imperative language, and argue endlessly over the
distinction. On the one hand, it has neither conditionals nor
recursion nor loops; in fact, it has no explicit control structures at
all. On the other hand, it does describe actions rather than just
relationships, which distinguishes it from a purely declarative syntax
like Glade GUI descriptions.
Run-control minilanguages for complex programs often straddle
this border. We're making a point of this fact because not having
explicit control structures in an imperative minilanguage can be a
tremendous simplification if the problem domain lets you get away
with it.
One notable feature of .fetchmailrc syntax
is the use of optional noise keywords that are supported simply in
order to make the specifications read a bit more like English. The
‘with’ keywords and single occurrence of
‘options’ in the example aren't actually necessary, but
they help make the declarations easier to read at a glance.
