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Newsgroups: comp.lang.ada
Subject: Re: Ada Popularity: Comparison of Ada/Charles with C++ STL (and Perl)
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From: jayessay <nospam@foo.com>
Organization: Tangible
Date: 23 Sep 2004 15:10:36 -0400
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Date: 2004-09-23T15:10:36-04:00
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kevin.cline@gmail.com (Kevin Cline) writes:

> Bj�rn Persson <spam-away@nowhere.nil>
> > Kevin Cline wrote:
> > 
> > > Ada/Charles 158 lines, 9 files
> > > C++         76 lines
> > > Perl        14 lines
> > 
> > Neat. Now let's take three identical persons who haven't seen this 
> > program before, give them one version each, and see how long it takes 
> > them to understand it.
> > In other words: What matters is how easy the program is to read and 
> > maintain. 

Here is a quick hack Common Lisp version.  It is 11 "lines".  You
could get rid of a couple more 

(defun word-count (file-spec &key (wordpat (compile-pattern "[A-Za-z]+")))
  (let ((words->count (make-hash-table :test #'equal :size 10007)))
    (with-open-file (in file-spec :direction :input)
      (loop for line = (read-line in nil nil)
	    while line
	    do (replace-match
		:source line :target wordpat :every-occurance t
		:replacement #'(lambda (word)
				 (incf (gethash word words->count 0)) ""))))
    (format t "~{~A~^~%~}"
      (subseq (sort (all (w c) :in words->count) #'> :key #'second) 0 10))))

This also does all the checking of the C++ and Ada versions as well.


> I quite agree, and on that score the Perl code wins hands down. 

I don't much like Perl (too much line noise), but I still think you
are right here.  It took just a glance at the Perl to know what the
basic "spec" was (including just printing the top ten).  OTOH, I think
the above Lisp is significantly more readable than any of them as it
is both short and very descriptive.


> It's pretty hard to make the case that this Ada code:
> 
>   procedure Insert (Word : String) is 
>     I : Wordcount_Maps.Iterator_Type; 
>     B : Boolean; 
>     type Element_Access is access all Wordcount_Maps.Element_Subtype;
> 
>     for Element_Access'Storage_Size use 0;
> 
>     function To_Access is new Wordcount_Maps.Generic_Element
> (Element_Access);
>   
>   begin -- Insert 
>     Insert (Map, To_Lower (Word), 0, I, B); 
>     declare E : Wordcount_Maps.Element_Subtype renames To_Access
> (I).all;
>     begin 
>       E := E + 1; 
>     end; 
>   end Insert;
> 
> is easier to understand than the corresponding C++ code:
>   ++concordance[word];
> 
> or the corresponding Perl code:
>   ++$count{$word};

Or the non library, out of the box Lisp:

(incf (gethash word words->count 0))

What's more, it will be at least as fast as the C++ or Ada.


/Jon

-- 
'j' - a n t h o n y at romeo/charley/november com