accesing internal codes used for an enumeration

[Marius Amado Alves <alves@systran.lu>]

I am trying to implement a lexicon (in the database sense) as an
enumeration with a representation clause.

Example lexicon:

  Name <-> Code
  -------------
  Ping      123
  Pong      456

Implementation:

  type Names is (Ping, Pong);
  for Names use (Ping => 123, Pong => 456);

I found out the hardway that attribute Pos does not return the internal
code.  The ARM says this at 13.4(11), and tells you to use
Unchecked_Conversion instead--but does not instruct you on the types of
the conversion.  Where might one learn that?  Thanks.

/* The point of a lexicon is to access its elements by either key.  I
expect the implementation above would be eficient.  It is already simple
to declare/define.  The alternative is of course to use arrays, but then a
search procedure is needed.  I also wanted to avoid this complication. */

-- 
Marius Amado Alves
 alves@systran.lu
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