Re: [MUD-Dev] Properties of computer languages

[Hans-Henrik Staerfeldt <hhs#cbs,dtu.dk>]

On Wed, 16 Jun 1999, Caliban Tiresias Darklock wrote:
>
> I'm in the process of redesigning the macro language of my game, and I
> recall seeing at one time a list... a very short list... of things that a
> computer language absolutely required. Sort of a bare-bones "what you need
> to do everything you need to do in any given program". Two of the things on
> the list were conditionals (if/then/else) and iteration (for/next and
> do/while). There were either two or three other things listed, but I don't
> remember what they were. Does anyone here have a memory spark going off as
> to what list I'm talking about and where I can find it? I think one of the
> other things was something along the lines of subroutine/function declaration.

To all the the answers taking a turn into the computability area of
languages, .. c'mon guys :-) you know this is not what he's looking for!
(although it might be interresting, i know i have programmed in lambda 
calculus, actually accomplishing a multiplication function after an 
hour ... uck!).

Anyway, since i did some HCI work with evaluation of computer languages
i might give a few hints (in the opposite corner). There are, in my opinion
one important factor in the design of programming language;

  The ability for the constructs of the programming language
  to easily express the mental models of the problem that
  the language is used to solve.

Now, if you are going to make your own programming language, i propose
that you foremost examine the sort of problems that is to be solved 
with it. Take a declarative programming language as Prolog. Here the 
constructs are declarative logic, and in my oppinion, prolog very nicely 
hides all the messy details of pattern matching and the like from your mind. 
For many tasks, you do not have to think hard about how to present your 
knowledge to prolog. However, to other tasks, prolog stink. Where the 
mental models of the problem conflict with the constructs of the language, 
you have to 'bend' your understanding into expressing it with the 
programming language you use. 

Another factor here, is that ofcause you get better at this with training.
Therefore, it would be a bad idea to trust your own judgement in 'how
the world is percieved' bu the programmer. You will be influenced by you
own (and very accurate) perception of how the world works. However, it might
not at all be how the builders or players percieve what is going on.

You should rather ask a builder (or whoever is going to use the language)
how they percieve the game, and try to express their mental model in the
programming language paradigm. Ofcause if the builders are all with
hard experience in C/Java programming, by all means do not choose a 
declarative programming language. But if the language is to be used to 
solve AI problems, i would choose a functional or declarative language.

If the language supposed to be control and monitoring of sorts, perhaps
a dataflow oriented language would be best.


For a simple imperical language, i'd personally prefer C-style (as im
most trained in that). Make sure you get 

  variables
  arrays    (preferably dynamic)
  functions
  if/then/else/switch
  while/for
 
.. and a nice interface to the game.

  seconday, you might want to experiment with user defined structures,
  but this depends on what tasks the language is used for, weather it
  is really needed.


Secondary to the design, is that the programmer should have some easy
measure for the complexity if the program. In some languages, this is
done less well (like prolog), but it is always nice to be able to
guess how efficient your program is.


Hans Henrik Stærfeldt   |    bombman#diku,dk    | work:  hhs#cbs,dtu.dk      |
address:                |___  +45 40383492    __|__       +45 45252425     __|
 Dybendalsvej 74 2. th, | Scientific programmer at Center for Biological     |
 2720 Vanløse, Danmark. |  Sequence Analysis, Technical University of Denmark|




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