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Date: Thu, 30 Jun 2005 15:32:48 -0400
From: Matthew Heaney <mheaney@on2.com>
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Newsgroups: comp.lang.ada
Subject: Re: How difficult is ada to learn?
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Date: 2005-06-30T19:32:48+00:00
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Gene wrote:
> 
> You perfectly illustrated what I meant.  The overloaded plus
> constructor is quite idiomatic.

And the syntax for Pascal sets isn't idiomatic???  Anyway, we're 
comparing apples and oranges; see my post about Ada's built-in sets.

But even the new set container looks an awful lot like Pascal.  For 
example, the tutorial here:

http://www.geocities.com/SiliconValley/Park/3230/pas/pasl1010.html

gives these examples:

exclude(myday,Friday);
include(myday,Friday);

That's no different from:

declare
    myday : Day_Sets.Set;
begin
    ...
    Exclude (myday, Friday);
    Include (myday, Friday);
end;

Again, Ada's choice of names here is quite deliberate.

If you're a teacher, it wouldn't take any effort to provide a helper 
package for your students, something like:

with Ada.Containers.Ordered_Sets;
generic
    with package Sets is new Ada.Containers.Ordered_Sets (<>);
    use Sets;
package Generic_Set_Arrays is
    type Element_Array is
      array (Positive range <>) of Sets.Element_Type;

    function To_Set (Element : Sets.Element_Type) return Set;
    function To_Set (Elements : Element_Array) return Set;
    function "+" (E : EA) return Set renames To_Set;

    function "and" (L : Set; R : EA) return Set;
    function "or" (L : Set; R : EA) return Set;
    ...

    function "and" (L, R : EA) return Set;
    function "or" (L, R : ET) return Set;
    ...
end Generic_Set_Arrays;

Given overloadings like these, it's not even necessary to use the "+" 
conversion operator:

declare
    S1 : Set := To_Set (1);
    S2 : Set := S1 and (2, 3, 4);
    S3 : Set := S2 or (4, 5);
    S4 : Set := (6, 7) and (7, 8);
begin ...

I can't imagine students who are struggling with the syntax for Ada sets 
to have an easier go of it in similar languages as C++, Java, etc, which 
are also taught in contemporary CS curricula.

Yes, Pascal has slightly more built-in support for sets than Ada does 
(i.e. syntax for a set literal), but sooner or later students will have 
a need for a more sophisticated set, that can store more than elements 
of a discrete type with small range of values.  And eventually they'll 
need a map or a list, and then what will they do?