Re: Swarm technology preview

[Rod Price]

Hooray for declarative programming!  I'm working hard to get some
aspects of it injected into my organization at TRW.  I think it
will be a wonderful interface for Swarm.  

I did want to comment, however, on the distinction you seem to be
making between static, strongly typed imperative languages and 
dynamic, weakly typed declarative languages.  There are several 
declarative (actually, functional) languages which are strongly 
typed, yet dynamic in the sense that they use higher-order 
functions.  Two of the most well-known are Haskell, a pure 
functional language, and ML, a functional language with side
effects.  Each of these has a very strong (in fact, mathematically
consistent) type system, yet are purely declarative.  In Haskell,
for example, you can write a quicksort as

quicksort []     = []
quicksort (x:xs) = quicksort [ y | y <- xs, y <= x]
                ++ [x]
                ++ quicksort [ y | y <- xs, y > x]

The Haskell interpreter (or compiler) infers the type of the 
function quicksort at compile time as 

quicksort :: [a] -> [a]

meaning quicksort takes a homogeneous list of data (Ints, Floats,
or anything else) and returns another homogeneous list of the
same type of data.  Any other attempted use of quicksort gives an
error at compile time, not at runtime.

Personally, I think that this combination of strong typing and 
declarative programming is very powerful.  I find that if I can
get a function to compile, it will usually do what I expect.

You can find out more about Haskell at http://www.haskell.org, and
the Objective CAML dialect of ML at http://pauillac.inria.fr/ocaml/.

-Rod Price
TRW Denver
303-360-4428


"Marcus G. Daniels" wrote:
> 
> Here's a heads-up on recent developments of the Swarm Development Group.
> This is a paper and some associated software for a talk I gave at a
> a workshop on agent-based simulation at the University of Chicago.
> 
>   http://www.santafe.edu/~mgd/anlchicago.html
>   ftp://ftp.santafe.edu/pub/swarm/users-contrib/anarchy/anl-0.0.tar.gz
>   http://www.cas.anl.gov
> 
>


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