[mercury-users] Pred defns

[Fergus Henderson]

On 30-Mar-1998, John Griffith <griffith at sfs.nphil.uni-tuebingen.de> wrote:
> Why not have a user interface that (optionally) shows you which hidden
> arguments occur in a clause?  Wouldn't this give you the best of both
> worlds?

Well, that's a big can of worms you've just opened...

For example, is this user interface that you're thinking of going
to be able to show the hidden arguments in a CVS diff (a CVS diff
shows the changes between two different versions of a source file)? 
If so, how?

There are many advantages to keeping the language and the user
interface relatively separate.  If you don't, then you must
either expend a huge amount of effort in the user interface,
and *continue* investing large amounts of effort to maintain
its position relative to other user interfaces, or force your
users to suffer with a sub-standard user interface.
Furthermore, different users will want different styles of
user interface (for example if it doesn't support vi keybindings
and run well over a 14k modem, then I'd prefer something else)
so if you want your users to actually use the user interface then
you have to implement not one but several user interfaces.

I quite like the Eiffel (and Java) approach of having a tool which
can extract interfaces and spit them out in some standard form such
as HTML, which can be viewed with a variety of browsers.
However, browsing interfaces is different to editing source code,
so I don't think this approach would work nearly as well for
something like hidden arguments.

Even if you do have a bunch of nifty tools, I do find that typically
you spend a lot of time looking at the unadorned source code.

-- 
Fergus Henderson <fjh at cs.mu.oz.au>  |  "I have always known that the pursuit
WWW: <http://www.cs.mu.oz.au/~fjh>  |  of excellence is a lethal habit"
PGP: finger fjh at 128.250.37.3        |     -- the last words of T. S. Garp.