manual terminology: `procedure', `function' etc.

[Tim Pierce <twp@skepsis.com>]

When a Guile procedure is documented in the reference manual, how
should it be categorized?  Right now the manual uses `procedure' and
`function' somewhat arbitrarily, but several categories come to mind:
`function' for code that returns a useful value; `procedure' for
functions which do not; `primitive' for Guile functions coded in C;
`macro' for code defined with defmacro or define-syntax.

Is it useful to employ all of these terms?  My main worry was that it
would produce a confusing maze of indices.  However, it appears that
any code documented with `@deffn' and friends will appear in the same
index regardless of its documentation category, so that's not a cause
for concern.

love, T.