From: "Chad R. Meiners" <chad.rmeiners@gmail.com>
Subject: Re: initialize an array (1-D) at elaboration using an expression based on the index?
Date: Thu, 21 Oct 2010 06:44:47 -0700 (PDT)
Date: 2010-10-21T06:44:47-07:00 [thread overview]
Message-ID: <1f6bad81-e3d2-428b-a1a0-45acc7f96f68@m7g2000yqm.googlegroups.com> (raw)
In-Reply-To: i9amkr$goj$1@speranza.aioe.org
On Oct 15, 7:03 pm, "Nasser M. Abbasi" <n...@12000.org> wrote:
> Ada experts:
>
> I am not able to find an example on this.
>
> I was wondering if in Ada I can initialize some array, where I can fill
> the content of each entry in the array based on some function of the index?
>
> For example, in Fortran one can do this:
> -----------------------
> program main
> integer, parameter :: N = 10
> real, dimension(N) :: a=(/(j**2,j=1,N)/)
>
> print*, a
> end program
> ------------------------
> $ gfortran t3.f90
> $ ./a.exe
> 1.0000000 4.0000000 9.0000000 16.000000 etc....
>
> In Ada, what would I need to do in the initialization below?
> ---------------------------
> procedure t2 is
> N: constant integer := 10;
> a: array(1..N) of float := (others=>0.0); --??
> begin
> null;
> end t2;
> -----------------------------
>
> I know ofcourse I can initialize it in the body by a loop, just wanted
> to see if it is possible to do it in the elaboration.
>
> thanks
> --Nasser
We can borrow a page from either ocaml and F# and set up a generic
initialize function.
I don't have access to a compiler and I haven't programmed in Ada for
years, but below is the general idea.
generic
type T is array (I) of E;
with function expression(Index: I) return E;
function init return T is
val : T;
begin
for index in I'Range loop
val(index) := expression(I);
end loop;
return val;
end function;
procedure t2 is
N : constant Integer := 10;
type Foo is array(1..N) of float;
function exp(j : Integer) return float is return float(j**2); end
function;
function initFoo is new init(Foo,exp);
a : Foo := initFoo;
begin
null;
end t2;
for those interested how it would be done in F# (which has a type
generic init function for arrays):
let t2 () =
let N = 10 in
let a = Array.init N (fun j -> let j = j+1 in j*j |> float)
in ()
next prev parent reply other threads:[~2010-10-21 13:44 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-15 23:03 initialize an array (1-D) at elaboration using an expression based on the index? Nasser M. Abbasi
2010-10-15 23:31 ` Vinzent Hoefler
2010-10-16 0:16 ` Adam Beneschan
2010-10-16 0:29 ` Nasser M. Abbasi
2010-10-16 1:47 ` Robert A Duff
2010-10-16 1:01 ` Randy Brukardt
2010-10-16 10:08 ` Phil Clayton
2010-10-18 15:03 ` Adam Beneschan
2010-10-19 6:29 ` Randy Brukardt
2010-10-20 20:01 ` Phil Clayton
2010-10-19 16:34 ` Britt Snodgrass
2010-10-19 18:05 ` Jeffrey Carter
2010-10-19 19:00 ` Vinzent Hoefler
2010-11-10 14:33 ` Georg Bauhaus
2010-11-10 15:51 ` Adam Beneschan
2010-11-10 17:19 ` Dmitry A. Kazakov
2010-11-10 18:03 ` Adam Beneschan
2010-11-11 1:07 ` Georg Bauhaus
2010-11-11 8:30 ` Dmitry A. Kazakov
2010-11-11 12:02 ` Robert A Duff
2010-11-11 14:19 ` Georg Bauhaus
2010-10-16 0:52 ` Jeffrey Carter
2010-10-16 0:54 ` Gene
2010-10-16 1:11 ` Vinzent Hoefler
2010-10-21 13:44 ` Chad R. Meiners [this message]
2010-10-24 16:40 ` Shark8
2010-10-24 22:48 ` Phil Clayton
2010-10-25 2:23 ` Shark8
2010-10-29 23:26 ` Phil Clayton
2010-10-31 18:47 ` Shark8
2010-10-31 21:59 ` Georg Bauhaus
2010-11-01 0:45 ` Phil Clayton
2010-11-01 1:55 ` Shark8
2010-10-30 6:34 ` Brian Drummond
2010-10-31 19:00 ` Shark8
2010-10-31 18:09 ` (see below)
2010-10-31 19:35 ` Shark8
2010-10-31 22:47 ` (see below)
2010-11-01 0:07 ` Shark8
2010-10-31 23:21 ` (see below)
2010-10-31 21:26 ` Brian Drummond
2010-11-12 18:10 ` Randy Brukardt
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