After more experimenting with GUI in SML, I would like to now try calling an SML module from a C program. That way, the GUI could be built using traditional imperative techniques and the program logic could be written in SML. I see how to call a C function from SML, but and not so clear on how to call an SML function from a C program. I want to build code using polyc and then link with a C main program, but could anyone show me a simple example of calling that function and getting its return value? for example, I have defined:
fun sum i n f = if i > n then 0.0 else f i + sum (i+1) n f ; fun int2real x = real x ;
in linkToC.sml
and
#include <iostream> #include <fstream> std::ofstream ofs; int main() { std::cout << sum(1,10,int2real) << std::endl; ofs.open("table.dat"); for(int i = 0; i < 20; i++) ofs << i << '\t' << sum(1,i,int2real) << std::endl; }
in linkToC.cpp
Looking in the polyc script, I thought adding the -c option might allow me to build the object code which I could then link to the sml functions, but it complains about not having a main.
Could someone point me in the right direction? Thanks, Dave
On Mon, Dec 15, 2014 at 11:44 AM, David Topham <dtopham at gmail.com> wrote:
David, Thank you so much! I really appreciate your help with this. Your sample below builds fine with polyc on my system (PolyML 5.5.2). I am using a minimal Linux distribution named TinyCore ( http://distro.ibiblio.org/tinycorelinux/) which comes with OpenMotif 2.3.3 It runs in a virtual machine within another computer only taking up a few hundred MBs!
I am going to use it to help my students explore Discrete Math next semester (this textbook uses SML for that purpose: http://cs.wheaton.edu/~tvandrun/dmfp/).
I also found a reasonably current project using PolyML and Motif here: http://www.lemma-one.com/ProofPower/index/
...however it was built on PolyML 4 and has not yet been ported to the newer version (e.g. depends on PolyML.commit which no longer seems to be supported).
Happy Holidays to everyone in the PolyML community!
-David Topham
Re: GUI Interface (David Matthews)
I've experimented with building a stand-alone executable with Motif and succeeded in getting it to work for me using polyc. (It required building Poly/ML with --with-x). I took the example from http://www.polyml.org/docs/Motif.html and wrapped it up in a function. I did find a problem, though. It looks as though the function has to suspend itself with something like Posix.Process.pause otherwise nothing happens. I seem to recall that the Motif stuff is handled on a separate thread to allow the REPL to continue to accept commands. With a stand-alone application there isn't a REPL so without the "pause" it terminates immediately.
David
open XWindows ; open Motif ;
fun main() = let val shell = XtAppInitialise "" "xed" "Editor" [] [XmNwidth 400, XmNheight 400] ;
val main = XmCreateMainWindow shell "main" [] ;
val bar = XmCreateMenuBar main "bar" [] ;
val fileMenu = XmCreateCascadeButton bar "file" [XmNlabelString "File"] ; val editMenu = XmCreateCascadeButton bar "edit" [XmNlabelString "Edit"] ; val viewMenu = XmCreateCascadeButton bar "view" [XmNlabelString "View"] ; val helpMenu = XmCreateCascadeButton bar "help" [XmNlabelString "Help"] ;
val command = XmCreateText main "command" [XmNeditMode XmSINGLE_LINE_EDIT] ;
val hscroll = XmCreateScrollBar main "hscroll" [XmNorientation XmHORIZONTAL] ; val vscroll = XmCreateScrollBar main "vscroll" [XmNorientation XmVERTICAL] ;
val work = XmCreateDrawingArea main "work" [] ; in
XtManageChildren [fileMenu, editMenu, viewMenu, helpMenu] ; XtManageChildren [bar, command, hscroll, vscroll, work] ;
XmMainWindowSetAreas main bar command hscroll vscroll work ;
XtManageChild main ; XtRealizeWidget shell; Posix.Process.pause() end;
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End of polyml Digest, Vol 110, Issue 12
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