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From: RWK%SCH-GODZILLA@MIT-MC.ARPA
Newsgroups: net.works
Subject: WORKS Digest   V4 #18
Message-ID: <12374@sri-arpa.UUCP>
Date: Sun, 15-Apr-84 17:19:00 EST
Article-I.D.: sri-arpa.12374
Posted: Sun Apr 15 17:19:00 1984
Date-Received: Mon, 23-Apr-84 01:39:37 EST
Lines: 52

From:  "Robert W. Kerns" <RWK%SCH-GODZILLA@MIT-MC.ARPA>

    Date: 16 Apr 84 21:17:26-EST (Mon)
    From: ihnp4!drutx!houxe!hogpc!houti!ariel!vax135!floyd!clyde!
    From: watmath!utzoo!utcsrgv!peterr @ Ucb-Vax
Hippity hippity hop.
    Subject: Time for keyword parameters for prog. lang's

(Lots of assemblers and things have always supported keyword arguments,
especially in macros for some reason.  VMS makes big use of it, both
in languages and in commands).

    Still, the added typing, with increased chance of typos, *would* be a
    nuisance.  Fortunately, the technology is with us to avoid this extra
    typing.  A language-based editor can easily maintain a database of
    procedure parameters and present a procedure call template on demand.
    For example, if one types Lookup( then it could complete the
    statement, resulting in Lookup(name: _____, symIndex: ______) and
    position the cursor at the first field (type and parameter kind (pass
    by value, value-result, reference, etc.) information could also be
    presented).

    If anyone knows of a programming environment that supports such a
    scheme, I'd be grateful to hear about it.  Ada and, I believe, Mesa
    support keyword parameters, but I don't know if the APSE or Cedar
    environments have procedure call templates... does anyone out there
    know?

Zmacs (the editor on the Lisp machine), together with Zetalisp or Common
Lisp, provide you with aids along a somewhat parallel line.  While
you're typing in the arguments to a function, you can type
Control-Shift-A, and the argument list for the function will be
displayed at the bottom of your screen.  You still have to type in the
keywords (or positional arguments), but you don't have to remember how
to spell them.  It even tells you the default values, and if multiple
return values are declared, it tells you about those as well.

But this doesn't address the issue of saving typing.  I have had some
experience with template-based tools, in an editing package I put
together in EMACS for an experimental lisp-based languaged that was used
in Macsyma at one time.  I found there is a fundamental incompatibility
between keyword arguments and templates.  One of the most important
points to keyword arguments that they are amorphous.  You don't have to
include them all, and you don't have to include them in any specific
order.  I found I had to do nearly as much work to DELETE extraneous
keywords from the list as I would to type them in by hand.

The big advantage of templates, either in positional or keyword
syntaxes, is in the prompting they provide.  Zmacs provides this
quite handily.  But it would be fairly easy, now that I think of
it, to provide COMPLETION of keywords in Zmacs.  I think this would
come close to providing the best of both worlds.