🚀 go-pugleaf

In article <MYltLT200VsiM0U3Yx@andrew.cmu.edu>, gb17+@andrew.cmu.edu (George Thomas Baggott) writes:
> Is there some way to have a language with no side effects, yet still be
> able to solve this class of problems in a practical way?  If not what is
> the minimum amount of comprimise that must be made?
> 
> George

It would be  really nice to be able  to write programs that obey  some
reasonable set of semantics and are efficient to boot.  Unfortunately,
this doesn't happen very often.

#define SOAPBOX
This happens because when a language  is designed with  a semantics in
mind, the semantics  usually caters to  the mathematician  rather than
the machine.  Things that are easy  for the mathematician (e.g., sets,
closures, and mappings) are very  difficult  for  the idiot savants we
call    computers.   That's why   it's   easy to   write a declarative
description  of a  dictionary that  runs really  S  L O  W.   If  only
programs ran at the Speed of Mathematics (tm).

One possible solution  is to build new  machines that are  designed to
work  well with our  current  notions of semantics.  Many  strange and
wonderful architectures have  resulted from this kind  of exploration.
However, they seem to  be very specific in  the types of problems that
they solve.

A better idea is to work  on the mathematical end  of things so we can
design efficient Von Neuman type languages that have a strong semantic
foundation.

#undefine SOAPBOX

As far as  the dictionary example is concerned,  you   always want  to
modify (rather than copy) the state of the dictionary when you  can do
so without breaking the semantics of the program.

If there is just one reference  to the dictionary during the execution
of your program, then it's ok to modify it.  If there is more than one
reference, then  you need to  copy it.  (If  there are  no references,
then get rid of it).

If your program were written in the Most Perfect  Language (MPL), then
you should be able to combine the semantics of MPL  with the semantics
of your program to determine  which implementation of dictionary_add()
is best.

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Andrew K. Turk
visix!andyt@uunet.uu.net

        "I don't know what happened to my face." -- Dizzy Gillespie
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