Re: Ideas for Ada 200X

["Robert I. Eachus" <rieachus@attbi.com>]

> A nice cure for that is forcing yourself to write a bigger project in
> Perl and then try to debug it a week later to find the errors in the
> code. You might even give it to somebody else and ask her/him to
> introduce some bugs in your code, and then you do the debugging.

You should try APL for a real write once read never language.  I know of 
  several "large" APL programming projects that had a rule that 
functions had no more than one line of code, and you never documented 
how it did anything, just what it did.  Maintenance programming began by 
reading the comments and throwing the line of code away.

As a good example of this style of programming it takes eighteen 
characters in APL to find all the numbers in a vector of sequential 
integers starting at one that can be represented in exactly two ways as 
the product of two integers.  (In other words find all primes less than 
a given integer value N.)

Or you can use seventeen characters if instead you find all integers 
that are not the product of two integers greater than one.  A slightly 
more complex definition of primes, but easier in APL.

But if you really want to be efficient in generating primes, use 
Wilson's Theorem.  A number P is prime iff (P-1)! mod P is congruent to 
-1 mod P. In APL that only takes sixteen characters.  ;-)

No, the number of characters is not the only measure of efficiency.  But 
if you think about the last algorithm, in a implementation with "bignum" 
integer support, it takes one temporary, and one multiply and one mod 
operation per number tested.