Re: [Bug-apl] fpc/freepascal interface

[enztec]

a grand geocentric (aplcentric) point of view indeed - i'm pretty sure the 
number of pascal users is orders of magnitude greater then the number of apl 
programmers

On Tue, 18 Jun 2019 22:10:20 +0200
Dr. Jürgen Sauermann <address@hidden> wrote:

> Hi,
> 
> I believe that extending some language X with an interface to APL makes only
> sense if:
> 
> 1. language X is popular or at least is gaining popularity, and
> 2. (GNU-) APL can provide an advantage in an area where language X is weak.
> 
> According to http://statisticstimes.com/tech/top-computer-languages.php
> and others, C/C++ and python are the most frequently used languages
> today, with Erlang and Pascal having a far lower popularity (although
> probably increasing for Erlang but decreasing for Pascal).
> 
> Erlang and Python are both weak for large vectors and even weaker for
> arrays with higher ranks. Reason is the linked list structure that they use
> for vectors.
> 
> Now to Pascal: it is not popular and is not weak in a particular area (being
> weak in total does not count here). A further difficulty is the need to 
> declare
> the data types of variables beforehand, which does not fit well to the dynamic
> typing of APL. Python and Erlang are both dynamically type and therefore
> this problem does not exist for them.
> 
> For that reason you are on your own when it comes to extending Pascal with
> GNU APL. I will be glad to help you with technical advice how to do that and
> how GNU APL works internally, but I would prefer not be involved in  building
> such an interface.
> 
> Best regards,
> Jürgen
> 
> 
> 
> On 6/17/19 5:05 PM, address@hidden wrote:
> 
> Hi  Jürgen,
> 
> Regarding fpc it depends on how they have built their C/C++ interface (if 
> they did).
> The last time I used Pascal was the time when the only other programming
> language on my platform was BASIC. So I am not really up-to-date with Pascal.
> If you want to try it, then I can help with technical information that you 
> may need.
> 
> this is the fpc/c/c++ interface guide that i have used for accessing c libs 
> from fpc
> using c++ in fpc is a lot more complicated - i have 'working examples' from 
> the following guide (hello++.pas) but that is it for c++.
> ftp://ftp.freepascal.org/pub/fpc/docs-pdf/CinFreePascal.pdf
> 
> This is an example of the c interface (how i can use 'c/libc' from fpc)
> 
> this can be your first fpc program!!
> 
> // sysconf.pas
> program sysconf; // see man 3 syscon
> uses ctypes;
> const _SC_NPROCESSORS_ONLN = 84; // _SC_NPROCESSORS_ONLN  The number of 
> processors currently online (available).
> function sysconf(i: cint): clong; cdecl; external 'c'; // libc unistd.h
> begin
> writeln(sysconf(_SC_NPROCESSORS_ONLN), ' cpus : _SC_NPROCESSORS_ONLN');
> writeln;
> end.
> 
> to compile
> fpc -XX sysconf.pas # -XX use smart linking to get smallest executable   use 
> -gl for generating debug info for gdb and use lineinfo unit
> 
> ---
> 
> The shell approach is fine as long as your programs process a small to medium
> amount of data. When the volume of data becomes huge then you have a lot of
> overhead (formatting on the shell side and tokenization and optimization on 
> the
> APL side) which can only be avoided by calling directly into the APL 
> interpreter.
> 
> so far i've had no problem using cli apl from fpc (there are actually 2 ways 
> depending on if i want to 'trap' and use any apl standard output 
> (aprocess.execute) or not (sysutils.executeprocess)
> 
> program fpcapl;
> uses sysutils;
> var l : ansistring;
> begin
> l := '-c "/usr/local/bin/apl --cfg"';
> //l := '-c "/apl/workspaces/script.apl"'; //  script.apl file   has    #! 
> /usr/local/bin/apl --script --     then apl code
> sysutils.executeprocess('/bin/bash', l); // apl standard output just displayed
> end.
> 
> 
> 
>