How difficult is ada to learn?

How difficult is ada to learn?

[Sm704]

How difficult is the Ada programming language to learn? I have
Pascal/Object pascal experience, and want to move to a new language
soon. C/C++ is too scary for my tastes. I was considering either Ada or
modula2 as my next language. How does Ada compare in power to modula2
and the Borland's dialect of Pascal?

Thanks

Re: How difficult is ada to learn?

[Ludovic Brenta]

"Sm704" writes:
> How difficult is the Ada programming language to learn? I have
> Pascal/Object pascal experience, and want to move to a new language
> soon. C/C++ is too scary for my tastes. I was considering either Ada
> or modula2 as my next language. How does Ada compare in power to
> modula2 and the Borland's dialect of Pascal?
>
> Thanks

I would say:

Pascal < Modula-2 < Object-Pascal < Ada

But, if you know Object-Pascal, learning Ada won't be too difficult
for you.  The main areas where you'll learn new things are tasking and
the Ada way of doing OOP.

I suggest you read the following article, which will help you:

http://homepage.sunrise.ch/mysunrise/gdm/pascada.htm

HTH

-- 
Ludovic Brenta.

Re: How difficult is ada to learn?

[Preben Randhol]

On Thu, Jun 30, 2005 at 07:11:17AM +0200, Ludovic Brenta wrote:
> I suggest you read the following article, which will help you:
> 
> http://homepage.sunrise.ch/mysunrise/gdm/pascada.htm

and http://www.adapower.com/ where you will find on-line books on Ada.


-- 
Preben Randhol -------------- http://www.pvv.org/~randhol/Ada95 --
                 �For me, Ada95 puts back the joy in programming.�

Re: How difficult is ada to learn?

[Gene]

There are really two answers.  If you intend to structure programs as
in the other languages, then it's quite easy to shift sideways into Ada
syntax.  If you want to exploit Ada's full power, then you'll have to
figure out the Ada way to do things and learn the parts of the langauge
that are not found elsewhere---task types for example.  In that regard,
one of the best things about Ada is that the language designers put
their thinking in the rationale documents and then Cohen took the whole
art of explaining how to use a langauge to a new level.  There is so
much glop out there on the language-of-the-week that these two books
really stand out.

Most people who start with Borland Pascal miss the built-in set and
string data types. Ada gets the same effects with packages, but the
syntax is far less elegant and readable.  (disclaimer: I have no real
Modula2 experience)

GR

Re: How difficult is ada to learn?

[Matthew Heaney]

Gene wrote:
> 
> Most people who start with Borland Pascal miss the built-in set and
> string data types. Ada gets the same effects with packages, but the
> syntax is far less elegant and readable.

I haven't done any Pascal in a while, so I don't remember the syntax for 
set manipulation, but Ada 2005 will have a set container type.  It's an 
abstract data type, declared in a package in the normal way.  It 
supports union, intersection, etc.

If not having "built-in" syntax is a hardship, then you can always 
define array-based set operations yourself.  For example, suppose we 
have a set whose element type is Integer, then we can do this:

type Integer_Array is array (Positive range <>) of Integer;

function "+" (IA : Integer) return Integer_Sets.Set is
   S : Set;
begin
   for Indx in IA'Range loop
      S.Include (IA (Indx));
   end loop;

   return S;
end;

Now you can say:

declare
    S1 : Set := +(1, 2, 3);
    S2 : Set := +(2, 3, 4);
    S3 : Set := S1 or S2;
    S4 : Set := S3 and +(1, 3);
    S5 : Set := +(42, 43) or +(44, 45);
begin  ...;

That's not that inelegant.  Not much different from Pascal, as I recall...

Re: How difficult is ada to learn?

[Duncan Sands]

> > Most people who start with Borland Pascal miss the built-in set and
> > string data types. Ada gets the same effects with packages, but the
> > syntax is far less elegant and readable.
> 
> I haven't done any Pascal in a while, so I don't remember the syntax for 
> set manipulation, but Ada 2005 will have a set container type.  It's an 
> abstract data type, declared in a package in the normal way.  It 
> supports union, intersection, etc.

Don't forget that arrays of booleans automatically have "and", "xor" and "or"
defined (i.e. intersection, symmetric difference and union), so can be used for
sets.

All the best,

Duncan.

Re: How difficult is ada to learn?

[Gene]

Thanks!  You're absolutely right that sets are less of an issue than
strings.  I overstated by saying "most people."  My reference point is
undergrads in CS1, where small things can make a difference.

You perfectly illustrated what I meant.  The overloaded plus
constructor is quite idiomatic.  In Pascal, set construction just
happens. So students who know sets as an early exercise in Pascal do a
doubletake when they try the same in Ada.  This mysterious-looking plus
pops up, and they must dig in to figure out operator overloading and
parameterized types in order to do what used to be self-evident.  This
isn't a bad thing, but it does cause them to "miss" Pascal sets.

Best regards,
Gene

Re: How difficult is ada to learn?

[Matthew Heaney]

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?

Re: How difficult is ada to learn?

[Randy Brukardt]

"Matthew Heaney" <mheaney@on2.com> wrote in message
news:42c40313$0$32193$39cecf19@news.twtelecom.net...
Matt Heaney wrote:

> If not having "built-in" syntax is a hardship, then you can always
> define array-based set operations yourself.  For example, suppose we
> have a set whose element type is Integer, then we can do this:

The following example seems pretty confused.

> type Integer_Array is array (Positive range <>) of Integer;
>
> function "+" (IA : Integer) return Integer_Sets.Set is

What's the definition of "Integer_Sets.Set"? Shouldn't IA have type
Integer_Array, rather than Integer?

>    S : Set;
> begin
>    for Indx in IA'Range loop
>       S.Include (IA (Indx));
>    end loop;
>
>    return S;
> end;
>
> Now you can say:
>
> declare
>     S1 : Set := +(1, 2, 3);
>     S2 : Set := +(2, 3, 4);
>     S3 : Set := S1 or S2;
>     S4 : Set := S3 and +(1, 3);
>     S5 : Set := +(42, 43) or +(44, 45);

Presuming that Integer_Sets.Set has "or" and "and" operations.

                            Randy.

Re: How difficult is ada to learn?

[Matthew Heaney]

Randy Brukardt wrote:
> 
>>type Integer_Array is array (Positive range <>) of Integer;
>>
>>function "+" (IA : Integer) return Integer_Sets.Set is
> 
> 
> What's the definition of "Integer_Sets.Set"? Shouldn't IA have type
> Integer_Array, rather than Integer?

Yes.  A slipe of the ... fingers.


> Presuming that Integer_Sets.Set has "or" and "and" operations.

Yes.  Integer_Sets is an instantiation of Ada.Containers.Ordered_Sets.

Re: How difficult is ada to learn?

[Matthew Heaney]

Gene wrote:
> 
> Most people who start with Borland Pascal miss the built-in set and
> string data types. Ada gets the same effects with packages, but the
> syntax is far less elegant and readable.

Thinking about it some more, I forgot that Ada does built-in support for 
sets a la Pascal, in the form of arrays whose component subtype is 
Boolean.  There are predefined operations for and'ing, or'ing, etc.

Of course, sets of this type have the same constraints as Pascal, 
meaning that the element type must be discrete and constrained, e.g. 
subtypes of Character or Integer, etc.

The languages aren't much different here (as you might expect, given 
Ada's pedigree).

Re: How difficult is ada to learn?

[Robert A Duff]

Matthew Heaney <mheaney@on2.com> writes:

> Gene wrote:
> > Most people who start with Borland Pascal miss the built-in set and
> > string data types. Ada gets the same effects with packages, but the
> > syntax is far less elegant and readable.
> 
> Thinking about it some more, I forgot that Ada does built-in support for
> sets a la Pascal, in the form of arrays whose component subtype is
> Boolean.  There are predefined operations for and'ing, or'ing, etc.

Right.  And you normally want to use pragma Pack on that array.

Ada's array-of-boolean doesn't have the annoying restriction of Pascal
sets to a small range.  If you want 10_000 bits, that's fine in Ada,
but Pascal compilers typically won't allow it.

The Pascal syntax for sets is nicer than Ada's, though.

- Bob

Re: How difficult is ada to learn?

[Waldek Hebisch]

Robert A Duff <bobduff@shell01.theworld.com> wrote:
> Ada's array-of-boolean doesn't have the annoying restriction of Pascal
> sets to a small range.  If you want 10_000 bits, that's fine in Ada,
> but Pascal compilers typically won't allow it.
> 

Use good Pascal compiler. GNU Pascal sets are limited by integer size.
On 32-bit machines you are still limited to 256 MB (while packed bit array
is able to use 64-bit indices and fill whole 4GB), but on 64-bit machines
the other limits strike first. Even on 32-bit machines I would not
call it "small range".

-- 
                              Waldek Hebisch
hebisch@math.uni.wroc.pl 

Re: How difficult is ada to learn?

[Ludovic Brenta]

Waldek Hebisch <hebisch@math.uni.wroc.pl> writes:
> Robert A Duff <bobduff@shell01.theworld.com> wrote:
>> Ada's array-of-boolean doesn't have the annoying restriction of
>> Pascal sets to a small range.  If you want 10_000 bits, that's fine
>> in Ada, but Pascal compilers typically won't allow it.
>> 
>
> Use good Pascal compiler. GNU Pascal sets are limited by integer
> size.  On 32-bit machines you are still limited to 256 MB (while
> packed bit array is able to use 64-bit indices and fill whole 4GB),
> but on 64-bit machines the other limits strike first. Even on 32-bit
> machines I would not call it "small range".

Why would I use a good Pascal compiler if I already use an Ada compiler?

-- 
Ludovic Brenta.

Re: How difficult is ada to learn?

[Jeffrey Carter]

Matthew Heaney wrote:
> 
> Of course, sets of this type have the same constraints as Pascal, 
> meaning that the element type must be discrete and constrained, e.g. 
> subtypes of Character or Integer, etc.

They don't have to be subtypes. In Pascal, there were often limits on 
the range of the universe, and the compiler would reject sets over too 
large a universe, but there's nothing in Ada to stop you from writing:

type Character_Set is array (Character) of Boolean;
pragma Pack (Character_Set);

type Integer_Set is array (Integer) of Boolean;
pragma Pack (Integer_Set);

C : Character_Set;
I : Integer_Set;

and the worst the compiler can do is issue a warning that the 
declaration will raise Storage_Error.

Actually, with a 32-bit Integer, Integer_Set will occupy 512 MB. That's 
less than the physical memory on many modern PCs, so you might not even 
get a warning.

-- 
Jeff Carter
"We call your door-opening request a silly thing."
Monty Python & the Holy Grail
17

Re: How difficult is ada to learn?

[Martin Krischik]

Sm704 wrote:

> How difficult is the Ada programming language to learn? I have
> Pascal/Object pascal experience, and want to move to a new language
> soon. C/C++ is too scary for my tastes. I was considering either Ada or
> modula2 as my next language. How does Ada compare in power to modula2
> and the Borland's dialect of Pascal?

Well I have Pascal/Modula 2 experience and found Ada a perfect replacement
for the two. Ada really is the Pascal for grown ups having all the features
which where missing in Pascal. Even Turbo-Pascal comes close to Ada's
Power. As for Modula-2: Apart from the nice support for modules the feature
set was in fact reduced when compared to Pascal.

If you want to learn more about Ada look at:

http://en.wikibooks.org/wiki/Programming:Ada

The are 192 Web Pages of tutorial material out there.

Martin
-- 
mailto://krischik@users.sourceforge.net
Ada programming at: http://ada.krischik.com

Re: How difficult is ada to learn?

[svaa]

If you have experience with Pascal, I don't think that will be very
difficult to learn. There are some new concepts like generics,
discriminants  and tasks. You will find things different like objects
and pointers, and you'll miss some things like an easy strings
management, sets, and little more.

In the other hand, I like Ada sintax for blocks, that is, you don't
see a cascade of wild "end", you see "end nameprocedure" or "end if"
etc. I like the restrictions of types, harder that pascal (and much
harder than C). I like that the standard has a lot, a big lot of
functions that are standard in any Ada compiler.

There is also a new way of doing things in Ada. You will need some
experience to get the touch.

If you use borland's products, you will miss a good IDE. Nowadays
languages have libraries (packages in Ada) some standard, some added
by vendor, and some added by yourself. There are thousands of
functions, procedures and data structures, all that information is
difficult to handle without good tools. Borland is a master in this
matter, good integrated help, fast access to record fields and to
methods of an object, etc. There is nothing like that in Ada, and
that's a big problem, specially for a beginner.

Re: How difficult is ada to learn?

[chris]

Sm704 wrote:
> How difficult is the Ada programming language to learn? 

Not very.  I found it easy to learn from a pascal background, so you 
should have no problem.

The Ada Lovelace tutorial is a quick intro, but for a more in depth you 
might want to look at Cohens "Ada as a second language" and Englishs' 
"Ada 95: The Craft of Object-Oriented Programming" are good.  Cohens 
goes over everything, but is a rather large book and that might be 
offputting.  Englishs' book isn't in print anymore, and is orientated 
towards beginners but it does cover Adas OO and generics well.

Re: How difficult is ada to learn?

[chris]

chris wrote:
> Sm704 wrote:

> The Ada Lovelace tutorial is a quick intro, but for a more in depth you 
> might want to look at Cohens "Ada as a second language" and Englishs' 
> "Ada 95: The Craft of Object-Oriented Programming" are good.  Cohens 
> goes over everything, but is a rather large book and that might be 
> offputting.  Englishs' book isn't in print anymore, and is orientated 
> towards beginners but it does cover Adas OO and generics well.

Crap.  Forgot to say that Ada: The craft is available online for free 
though!

Re: How difficult is ada to learn?

[Jeffrey Carter]

chris wrote:
> 
> Not very.  I found it easy to learn from a pascal background, so you 
> should have no problem.

The US Military Academy (West Point) did a controlled study that 
concluded that Ada was a better 1st language than Pascal. Presumably 
that means Ada's easier to learn than Pascal.

-- 
Jeff Carter
"We call your door-opening request a silly thing."
Monty Python & the Holy Grail
17