On Wed, 6 Nov 2013, mockturtle wrote:

> type Matlab_Name is new
>     String
>   with Dynamic_Predicate =>
>     (for all I in Matlab_Name'Range =>
>        Is_Alphanumeric (Matlab_Name (I)) or Matlab_Name (I) = '_')
>     and
>       Is_Letter (Matlab_Name (Matlab_Name'First));

I suggest to write the following.

   with Dynamic_Predicate =>
     (  Natlab_Name'Length > 0
      and then
        Is_Letter (Matlab_Name (Matlab_Name'First)
      and then
        for all I in Matlab_Name'First+1 .. Matlab'Last =>
          Is_Alphanumeric (Matlab_Name (I)) or Matlab_Name (I) = '_')
     );

(Warning: not syntax checked!)

The "Natlab_Name'Length > 0 and then" part is important -- your code would 
raise Constraint_Error if the Matlab_Name is the empty string.

The other modifications are a matter of taste.

For me, first checking the first character, and then checking the other 
characters is more intuitive than doing it the other way. Also, I rather 
avoid the redundant check for the first letter being alphanumeric or '_',
since the first character is checked for being a letter, anyway.

And I wouldn't bother to replace the second "and then" by "and", as it has 
been in your code. However, mixing "and then" and "and" requires 
additional brackets, which I would prefer to avoid.




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