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From: pjb@informatimago.com (Pascal J. Bourguignon)
Newsgroups: comp.lang.eiffel,comp.lang.ada,comp.lang.modula3,comp.programming
Subject: Re: Alternatives to C: ObjectPascal, Eiffel, Ada or Modula-3?
Date: Sun, 19 Jul 2009 17:28:31 +0200
Organization: Informatimago
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Date: 2009-07-19T17:28:31+02:00
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Andrea Taverna <a.tavs@hotmail.it> writes:
> I'm still learning CL and that's been enlightening so far.

Given that you have notions of CL, then you could postpone your choice
of programming language.  

You're interested in algorithms, so just write your algorithms in
s-exp forms.

I understand that it might be fun to let the computer execute the
algorithms to see how they work out (I assume you prove your
algorithms independantly of any execution, which I'll remind you can
only prove that you have errors, not that your algorithm is correct).

So you could write in Common Lisp the DSL (Domain Specific Language)
able to interpret or translate your algorithms into CL, for animation
purposes.


Later, when you have a collection of proven algorithms, you may write
(still in Common Lisp, why reject a winning team?), a translator to
convert your algorithmic s-exps into the target language of your
choice, be it Ada, Pascal, C, Eiffel, Fortran, Haskell, Modula-2 or
Modula-3, whatever you need.  It's almost trivial to generate such
code from a DSL expressed in s-exps.


C/USER1[602]> (algorithm gcd
                  (parameters (input a integer)
                              (input b integer))
                  (result integer)
                (cases
                 when (= a b) then (return a)
                 when (< a b) then (return (gcd (- b a) a))
                 when (> a b) then (return (gcd (- a b) b))))
GCD
C/USER1[603]> (gcd 42 12)
6
C/USER1[686]> (translate-to-c '(algorithm gcd
                                (parameters (input a integer)
                                 (input b integer))
                                (result integer)
                                (cases
                                 when (= a b) then (return a)
                                 when (< a b) then (return (gcd (- b a) a))
                                 when (> a b) then (return (gcd (- a b) b)))))

int gcd(int a,int b)
{
if((a)==(b)){
return(a);
}
else if((a)<(b)){
return(gcd((b)-(a),a));
}
else if((a)>(b)){
return(gcd((a)-(b),b));
}
}




-- 
__Pascal Bourguignon__