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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: Not intended for use in medical,
Date: 1997/05/10
Message-ID: <dewar.863254456@merv>#1/1
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References: <3.0.32.19970423164855.00746db8@mail.4dcomm.com>
 <dewar.862775250@merv> <5kl9qc$g4d@bcrkh13.bnr.ca>
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Organization: New York University
Newsgroups: comp.lang.ada
Date: 1997-05-10T00:00:00+00:00
List-Id: <comp.lang.ada>


<<Yes, I know these can all be done with ordinary procedures and generics,
and I know there's a limit to what you can cram into a language
specification. But in this case, I think it would have been politically
savvy to have included something like these attributes, as an answer to
the challenge from C++'s operators.>>

Bad reason! It is almost always a mistake in languages to make compromises
in the design on the grounds that users of language X won't be happy unless
you do. Every time I have seen this done I think it is a mistake. Three
examples:

In Algol-68

  Really we should make people write ref all the time because it is important
  for people to know that something is a variable, but if we make the normal
  declaration for an integer variable be:

     ref int x;

  Fortran and Algol-60 programmers will never tolerate it, so let's make
  a special rule -- that the ref is implied here, so we can write:

     int x;

  but only in this case, for other declaration forms, the ref is required.

  Bottom line: confusion, and surprise! Neither Algol-60 nor Fortran
  programmers like confusion!

In Ada 83 (and Ada 95)

  Really we should declare the type of everything, but Fortran users would
  never put up with

      for x in integer range 0 .. 10 loop ...

  so let's have a special rule that we get a default use of integer here.

  Similarly, Fortran users will never put up with having to declare all
  those array types, so let's allow anonymous array declarations:

  My opinion is that both these decisions are mistakes, they introduce
  irregularity and confusion.

People are not going to say, "Hey, let's use Ada because it has all the
goodies we know and love from language X". If that is their viewpoint,
there is a language that much more certainly has all the goodies from
language X, and that they are much more likely to use.

If people switch to a new language it is because they see some general
advantages. If they make the switch, they want to find something coherent
and well designed when they get there.

Features should go in a language because they make sense in terms of the
syntactic and semantic framework of the language, not because of some
perceived political value. That is especially true of tiny syntactic
gizmos.