Poly/ML

polyml@lists.polyml.org

2 participants
711 discussions

emacs SML mode
by dm＠prolingua.co.uk 20 Mar '15

20 Mar '15

Peter, I'm copying this to the Poly/ML list as you suggested. It would be nice to have SML emacs mode working with Poly/ML for those who would like to use it but my feeling is that it is rather old-fashioned. Poly/ML now supports a much more extensive interface designed for an IDE. The best example of this is Isabelle's ML mode. See http://sketis.net/2014/isabellepide-as-ide-for-standard-ml which has a nice screen-shot. Lucas Dixon and I both had a go at producing IDEs which were completely independent of Isabelle but we didn't get as far as Makarius has. It all works by having the Poly/ML compiler as a function which takes a large set of parameters most of which have simple defaults. All the interaction with the compiler is through ML functions. The default REPL just calls the compiler with streams connected to the console but it's very easy for a user to replace the REPL with something else. The Isabelle IDE is just using the Poly/ML compiler function but passing in parameters which capture error messages and also allow browsing of the parse-tree to get information about the types. So far the debugger hasn't been fully integrated with this but it's something I have in mind. The format that the default REPL uses for error messages was one that was used by various compilers at one time and it used to be possible to parse it automatically. If there's a more up-to-date format I'm happy to change to it. I don't know if anyone is parsing the current format automatically and would be inconvenienced by a change. David On 03/12/2014 03:26, Peter Gammie wrote: > Dave, > > I?ve been talking to Stefan about the SML mode for emacs that he > maintains. I?m hoping to use it with Poly/ML and it is starting to > come together. > > Stefan observed that it would be super-helpful if Poly/ML generated > errors in a standard format, such as e.g. the one that GCC or clang > use, as far as that makes sense. > > Would you be open to that? I could try to crank out some patches to > Poly/ML if so. > > BTW I am wondering how people interact with Poly/ML?s repl. With more > hacking it is likely to be somewhat emacs-friendly, but I?m still > struggling to understand how people have done it in the past. > > For instance, I presently more-or-less just load all modules into > poly with a series of ?use?s in dependency order. Now I?d like to use > the debugger and it seems I have to hack all this scaffolding to do > so. From the looks of it Isabelle does the same. > > Feel free to reply via the Poly/ML list if you prefer. > > Thanks for the awesome system. I hope I can make some use of the > concurrency! > > thanks, peter >

9 17

forgetVal(ue)
by peteg42＠gmail.com 15 Mar '15

15 Mar '15

David, I?ve been trying to repurpose your Poly/ML test harness, that encapsulates the tests in private namespaces. With some head scratching I got it to somewhat work, so thanks for that. One remaining nit is that the treatment of forgetVal(ue) does not take into account the current namespace. Did you have a reason for leaving it out of the PolyML.NameSpace.nameSpace record? cheers, peter

2 1

Typo in Socket.select
by hiroya.ebine1＠gmail.com 11 Mar '15

11 Mar '15

In Poly/ML source code, polyml/basis/Socket.sml, Socket.select function declared like this: val select: { rds: sock_desc list, wrs : sock_desc list, exs : sock_desc list, timeOut: Time.time option } -> { rds: sock_desc list, wrs : sock_desc list, exs : sock_desc list } But, basis library says: select {rds, wrs, exs, timeout} (http://sml-family.org/Basis/socket.html#SIG:SOCKET.select:VAL) It seems a typo. Argument "timeOut" shoud be "timeout". Please fix it or tell me where post a patch. Sorry for poor english. Thank you.

2 1

Debugging the debugger
by Brian.Campbell＠ed.ac.uk 07 Mar '15

07 Mar '15

Hi, I've encountered a few bugs when using the debugger, and I've managed to distill them down into a useful form. The first is that the compiler is too keen to avoid multiple calls to the debugger in one line. For example, if I debug the function below, 1 fun f n = 2 let val l = [1,2,3,4] 3 val x = map (fn y => y+n) l 4 in x 5 end then stepOver() will skip line 3, because the compiler places the only call to the debugger inside the anonymous function. I've been working around this by adding an extra newline after map. The second is that when support was added to stop execution when an exception is raised, it used the same code as when an exception exits a function, and pops an extra entry off the debug stack. The stepOver and stepOut functions get very confused as a result. I've hacked my copy to check whether the name ends in -raise before popping the stack, but there's probably a more elegant solution. Finally, the tracing doesn't seem to like datatypes declared inside structures: structure S = struct datatype t = A of int fun f (x:t) = x; end; > PolyML.Debug.trace true; val it = (): unit > S.f (S.A 5); S.f Exception- Subscript raised I can examine the value of x in the debugger, though, but my attempts to make the way tracing prints values more like the debugger toplevel haven't been successful. Best regards, Brian

2 1

extremely bad performance on some mllex generated code
by michael.norrish＠nicta.com.au 03 Mar '15

03 Mar '15

(I'll attempt to attach the tgz file to this message, but if 817KB is too big and this bounces or the attachment is dropped, I'll make it available separately.) If compiled with Poly/ML, the attached program performs abysmally on the provided testcase.sml input file. Within seconds of beginning, it attempts to allocate more memory than my machine has (16GB), and basically brings it to its knees. If compiled with mlton, the testcase doesn't seem to cause any obvious memory allocation, and finishes in less than a second. You can also compile with Moscow ML, though I haven?t included the build instructions in the Makefile. The execution of the mosml executable doesn't seem to allocate any memory either, and it terminates cleanly (after 17s). Though slow this is still preferable to Poly/ML's behaviour. This is with Poly/ML 5.5.2 on > Linux telemachus 3.2.0-75-generic #110-Ubuntu SMP Tue Dec 16 19:11:55 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux The Makefile generates two executables (if you have mlton and poly in your PATH): pholdeptool and mholdeptool. You can run them on the testcase, e.g.: pholdeptool testcase.sml The lexer code looks to me to be tail-recursive, and the program only accumulates a binary tree containing 15 strings. So it really does seem as if Poly/ML is doing something buggy. (The program is lexing the test-case (which uncompresses to a 30MB file) in an extremely simple way, but performing a useful analysis.) Michael

2 3

Lexical analyser bug?
by rda＠lemma-one.com 24 Feb '15

24 Feb '15

I mistyped a word constant and was a bit surprised by the error message. rda]- poly Poly/ML 5.5.2 Release > 0xw9; Error-malformed integer constant: 0w Static Errors Contrast this with SML/NJ: rda]- sml Standard ML of New Jersey v110.76 [built: Mon Mar 3 16:26:20 2014] - 0xw9; stdIn:3.2-3.5 Error: unbound variable or constructor: xw9 stdIn:3.1-3.5 Error: operator is not a function [literal] operator: int in expression: 0 <errorvar> With the following contrived example: fun f x y = print "Boo!" val xw9 = "xw9"; f 0xw9; Poly/ML reports a syntax error while SML/NJ and mlton both print Boo! I am not sure who is right about this. Regards, Rob.

4 4

C Interface documentation
by rda＠lemma-one.com 15 Feb '15

15 Feb '15

I am trying to help with porting some code that uses the C foreign function interface from Linux to Mac OS X and have been trying a toy example on both systems. I have actually been very impressed by how easy it was to get started with the interface, but I did note some small issues with the documentation. The first point is with the release notes, which do say that the C Interface was not supported on Mac OS X once upon a time, but don?t say that it is supported now. (Aside: do time profiling and polling work now too?) The web page about the C Interface says that load_lib will raise an exception if the dynamic library cannot be found. My experience on both OSes is that load_lib and load_sym don?t raise any exceptions. You get the exception when you try to call a C function. The documentation also says that it will kill your ML session if the file exists but has the wrong format, but that seems to have been fixed now. It says that if load_lib is called with a relative path name, then it will be interpreted with respect to the directory in which the ML session was started from. I don?t think this can be right. Surely you will get whatever behaviour dlopen gives you (and typically that will be a search involving environment variables like LD_LIBRARY_PATH and some OS-specific standard places like /lib). So, for example, if mylib.so is in the current directory and I pass ?mylib.so? to load_lib, on Fedora, I get load_lib <mylib.so> : mylib.so: cannot open shared object file: No such file or directory If I change ?mylib.so? on the call to load_lib to ?./mylib.so? or run with LD_LIBRARY_PATH=. or copy mylib.so into /usr/lib64, it works. On Mac OS X, on the other hand, if have ?mylib.dylib? in my current directory, load_lib will find it given the relative pathname, because dlopen on Mac OS X includes the current directory as one of the standard places. Regards, Rob.

1 0

linking polyML modules to C
by dtopham＠gmail.com 25 Jan '15

25 Jan '15

I wanted to follow through on this to expand the GUI to receive input, so this is the result (here and attached). The tgz file has the sml and script to build them as well. -Dave #include <stdio.h> #include <Xm/Xm.h> #include <Xm/RowColumn.h> #include <Xm/Label.h> #include <Xm/TextF.h> #include <Xm/PushB.h> #include <stdlib.h> #include <ctype.h> double (*sml_hypot) (double x, double y); static void EnterCallback ( Widget w, XtPointer clientData, XtPointer callData); Widget sideA, sideB, sideC; void c_main (void) { Widget shell, rowcol, button; XtAppContext app; int argc = 1; char* argv[] = {"PolyML GUI" }; shell = XtAppInitialize ( &app, "Memo", NULL, 0, &argc, argv, NULL, NULL, 0 ); rowcol = XtCreateManagedWidget ("rowcol", xmRowColumnWidgetClass, shell, NULL, 0); XmString xmstr; xmstr = XmStringCreateLtoR ( "Right Triangle", XmFONTLIST_DEFAULT_TAG ); XtVaCreateManagedWidget ( "message", xmLabelWidgetClass, rowcol, XmNlabelString, xmstr, NULL ); XmStringFree ( xmstr ); sideA = XmCreateTextField ( rowcol, "input", NULL, 0 ); XtManageChild ( sideA ); sideB = XmCreateTextField ( rowcol, "input", NULL, 0 ); XtManageChild ( sideB ); button = XtCreateManagedWidget("Calculate Hypontenuse", xmPushButtonWidgetClass, rowcol, NULL, 0 ); XtAddCallback ( button, XmNactivateCallback, EnterCallback, NULL); sideC = XmCreateTextField ( rowcol, "input", NULL, 0 ); XtManageChild ( sideC ); XtRealizeWidget ( shell ); XtAppMainLoop ( app ); return; } static void EnterCallback ( Widget w, XtPointer clientData, XtPointer callData ) { double a, b; printf ( "text entered = %s\n", XmTextFieldGetString ( sideA ) ); printf ( "text entered = %s\n", XmTextFieldGetString ( sideB ) ); a = atof(XmTextFieldGetString ( sideA )); b = atof(XmTextFieldGetString ( sideB )); double c; c = sml_hypot (a, b); /* call back to SML! */ printf("c = %.6f\n", c); char msg[256]; sprintf(msg,"%.1f", c); XmTextFieldSetString(sideC,msg); } On Thu, Jan 22, 2015 at 10:40 AM, David Topham <dtopham at gmail.com> wrote: > > > On Thu, Jan 22, 2015 at 10:36 AM, David Topham <dtopham at gmail.com> wrote: > >> Wonderful! Thank you so much for posting that Phil! >> >> I was not able to build the code using the Makefile because my system >> does not have libpolyml.so; >> however, the commands within the Makefile did work, so perhaps that file >> is not needed? >> I put them within the attached tgz file in a shell script. >> Here are the commands in that file: >> >> gcc -fPIC -g -Wall -c testlib.c -o testlib.o >> gcc -shared -Wl,-soname,testlib.so.1 -o testlib.so.1 testlib.o >> polyc call_c_test_10.sml >> LD_LIBRARY_PATH=. ./a.out >> >> and this runs successfully displaying the output in an X Window! >> >> I think this is a viable approach to integrating PolyML with a GUI or at >> least graphics output but of course will require lots of experimenting...I >> wish I had tons of time, but will only be able to try things >> once-in-a-while now that a new semester has begun. >> >> Here is the modified C program that invokes the Motif window: >> (but it is also in the attached tgz file if you want to try it) >> >> #include <stdio.h> >> #include <Xm/Xm.h> >> #include <Xm/Label.h> >> #include <stdlib.h> >> >> double (*sml_hypot) (double x, double y); >> >> void c_main (void) >> { >> double a, b, c; >> >> a = 3.0; >> b = 4.0; >> printf("a = %.6f\n", a); >> printf("b = %.6f\n", b); >> >> c = sml_hypot (a, b); /* call back to SML! */ >> >> printf("c = %.6f\n", c); >> fflush(stdout); >> >> char msg[256]; >> sprintf(msg,"c = %.6f\n", c); >> Widget shell; >> XtAppContext app; >> XmString xmstr; >> int argc = 1; >> char* argv[] = {"polygui" }; >> shell = XtAppInitialize ( &app, "Memo", NULL, 0, >> &argc, argv, NULL, NULL, 0 ); >> >> xmstr = XmStringCreateLtoR ( msg, XmFONTLIST_DEFAULT_TAG ); >> XtVaCreateManagedWidget ( "message", >> xmLabelWidgetClass, shell, >> XmNlabelString, xmstr, >> NULL ); >> XmStringFree ( xmstr ); >> XtRealizeWidget ( shell ); >> XtAppMainLoop ( app ); >> >> return; >> } >> >> >> >> >> >> >> >> >> >> >> On Thu, Jan 22, 2015 at 4:00 AM, <polyml-request at inf.ed.ac.uk> wrote: >> >>> Send polyml mailing list submissions to >>> polyml at inf.ed.ac.uk >>> >>> To subscribe or unsubscribe via the World Wide Web, visit >>> http://lists.inf.ed.ac.uk/mailman/listinfo/polyml >>> or, via email, send a message with subject or body 'help' to >>> polyml-request at inf.ed.ac.uk >>> >>> You can reach the person managing the list at >>> polyml-owner at inf.ed.ac.uk >>> >>> When replying, please edit your Subject line so it is more specific >>> than "Re: Contents of polyml digest..." >>> >>> >>> Today's Topics: >>> >>> 1. Re: linking polyML modules to C (Phil Clayton) >>> >>> >>> ---------------------------------------------------------------------- >>> >>> Message: 1 >>> Date: Wed, 21 Jan 2015 20:20:06 +0000 >>> From: Phil Clayton <phil.clayton at veonix.com> >>> To: polyml at inf.ed.ac.uk >>> Subject: Re: [polyml] linking polyML modules to C >>> Message-ID: <54C009F6.1050209 at veonix.com> >>> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" >>> >>> 19/01/15 12:19, David Matthews wrote: >>> > On 19/01/2015 04:34, David Topham wrote: >>> >> Thanks David for your response. >>> >> >>> >> While searching I found this comment you made earlier: >>> >> >>> >> "The foreign-function interface allows for call-back functions so >>> >> there is >>> >> the mechanism to produce a C function that when called calls an ML >>> >> function." >>> >> >>> >> in >>> >> >>> http://stackoverflow.com/questions/17580386/shared-libraries-in-poly-ml >>> >> >>> >> Doesn't this indicate a mechanism that allows an SML function to be >>> >> called >>> >> from C? >>> > >>> > Yes, but the "main program" still has to be in ML. You can call C >>> > library functions and pass an ML function as an argument. >>> >>> Or the ML functions can be passed via global variables that are >>> initialized from the ML side - see attached example. That may be easier >>> if there are a large number of ML functions. >>> >>> >>> > Actually, I did wonder whether this could be used as a way of exporting >>> > ML functions to create a library that could be called from a C main >>> > program and came to the conclusion that it was going to be too >>> > complicated. Poly/ML uses libffi to interface with C. libffi can >>> build >>> > closures that wrap around ML functions so that these can be passed into >>> > C. The format of the closure it constructs differs markedly depending >>> > on the particular architecture since different architectures have >>> > different calling conventions for C. The closure is a data structure >>> > with pointers in it. Exporting it would require turning the pointers >>> > into relocations that the linker/loader will understand. libffi simply >>> > doesn't provide that information. It's there by implication in the >>> > source code but not explicitly. >>> > >>> > David >>> > _______________________________________________ >>> > polyml mailing list >>> > polyml at inf.ed.ac.uk >>> > http://lists.inf.ed.ac.uk/mailman/listinfo/polyml >>> > >>> >>>

1 0

linking polyML modules to C (Phil Clayton)
by dtopham＠gmail.com 22 Jan '15

22 Jan '15

On Thu, Jan 22, 2015 at 10:36 AM, David Topham <dtopham at gmail.com> wrote: > Wonderful! Thank you so much for posting that Phil! > > I was not able to build the code using the Makefile because my system does > not have libpolyml.so; > however, the commands within the Makefile did work, so perhaps that file > is not needed? > I put them within the attached tgz file in a shell script. > Here are the commands in that file: > > gcc -fPIC -g -Wall -c testlib.c -o testlib.o > gcc -shared -Wl,-soname,testlib.so.1 -o testlib.so.1 testlib.o > polyc call_c_test_10.sml > LD_LIBRARY_PATH=. ./a.out > > and this runs successfully displaying the output in an X Window! > > I think this is a viable approach to integrating PolyML with a GUI or at > least graphics output but of course will require lots of experimenting...I > wish I had tons of time, but will only be able to try things > once-in-a-while now that a new semester has begun. > > Here is the modified C program that invokes the Motif window: > (but it is also in the attached tgz file if you want to try it) > > #include <stdio.h> > #include <Xm/Xm.h> > #include <Xm/Label.h> > #include <stdlib.h> > > double (*sml_hypot) (double x, double y); > > void c_main (void) > { > double a, b, c; > > a = 3.0; > b = 4.0; > printf("a = %.6f\n", a); > printf("b = %.6f\n", b); > > c = sml_hypot (a, b); /* call back to SML! */ > > printf("c = %.6f\n", c); > fflush(stdout); > > char msg[256]; > sprintf(msg,"c = %.6f\n", c); > Widget shell; > XtAppContext app; > XmString xmstr; > int argc = 1; > char* argv[] = {"polygui" }; > shell = XtAppInitialize ( &app, "Memo", NULL, 0, > &argc, argv, NULL, NULL, 0 ); > > xmstr = XmStringCreateLtoR ( msg, XmFONTLIST_DEFAULT_TAG ); > XtVaCreateManagedWidget ( "message", > xmLabelWidgetClass, shell, > XmNlabelString, xmstr, > NULL ); > XmStringFree ( xmstr ); > XtRealizeWidget ( shell ); > XtAppMainLoop ( app ); > > return; > } > > > > > > > > > > > On Thu, Jan 22, 2015 at 4:00 AM, <polyml-request at inf.ed.ac.uk> wrote: > >> Send polyml mailing list submissions to >> polyml at inf.ed.ac.uk >> >> To subscribe or unsubscribe via the World Wide Web, visit >> http://lists.inf.ed.ac.uk/mailman/listinfo/polyml >> or, via email, send a message with subject or body 'help' to >> polyml-request at inf.ed.ac.uk >> >> You can reach the person managing the list at >> polyml-owner at inf.ed.ac.uk >> >> When replying, please edit your Subject line so it is more specific >> than "Re: Contents of polyml digest..." >> >> >> Today's Topics: >> >> 1. Re: linking polyML modules to C (Phil Clayton) >> >> >> ---------------------------------------------------------------------- >> >> Message: 1 >> Date: Wed, 21 Jan 2015 20:20:06 +0000 >> From: Phil Clayton <phil.clayton at veonix.com> >> To: polyml at inf.ed.ac.uk >> Subject: Re: [polyml] linking polyML modules to C >> Message-ID: <54C009F6.1050209 at veonix.com> >> Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" >> >> 19/01/15 12:19, David Matthews wrote: >> > On 19/01/2015 04:34, David Topham wrote: >> >> Thanks David for your response. >> >> >> >> While searching I found this comment you made earlier: >> >> >> >> "The foreign-function interface allows for call-back functions so >> >> there is >> >> the mechanism to produce a C function that when called calls an ML >> >> function." >> >> >> >> in >> >> >> http://stackoverflow.com/questions/17580386/shared-libraries-in-poly-ml >> >> >> >> Doesn't this indicate a mechanism that allows an SML function to be >> >> called >> >> from C? >> > >> > Yes, but the "main program" still has to be in ML. You can call C >> > library functions and pass an ML function as an argument. >> >> Or the ML functions can be passed via global variables that are >> initialized from the ML side - see attached example. That may be easier >> if there are a large number of ML functions. >> >> >> > Actually, I did wonder whether this could be used as a way of exporting >> > ML functions to create a library that could be called from a C main >> > program and came to the conclusion that it was going to be too >> > complicated. Poly/ML uses libffi to interface with C. libffi can build >> > closures that wrap around ML functions so that these can be passed into >> > C. The format of the closure it constructs differs markedly depending >> > on the particular architecture since different architectures have >> > different calling conventions for C. The closure is a data structure >> > with pointers in it. Exporting it would require turning the pointers >> > into relocations that the linker/loader will understand. libffi simply >> > doesn't provide that information. It's there by implication in the >> > source code but not explicitly. >> > >> > David >> > _______________________________________________ >> > polyml mailing list >> > polyml at inf.ed.ac.uk >> > http://lists.inf.ed.ac.uk/mailman/listinfo/polyml >> > >> >>

1 0

polyml Digest, Vol 111, Issue 7
by dtopham＠gmail.com 22 Jan '15

22 Jan '15

Wonderful! Thank you so much for posting that Phil! I was not able to build the code using the Makefile because my system does not have libpolyml.so; however, the commands within the Makefile did work, so perhaps that file is not needed? I put them within the attached tgz file in a shell script. Here are the commands in that file: gcc -fPIC -g -Wall -c testlib.c -o testlib.o gcc -shared -Wl,-soname,testlib.so.1 -o testlib.so.1 testlib.o polyc call_c_test_10.sml LD_LIBRARY_PATH=. ./a.out and this runs successfully displaying the output in an X Window! I think this is a viable approach to integrating PolyML with a GUI or at least graphics output but of course will require lots of experimenting...I wish I had tons of time, but will only be able to try things once-in-a-while now that a new semester has begun. Here is the modified C program that invokes the Motif window: (but it is also in the attached tgz file if you want to try it) #include <stdio.h> #include <Xm/Xm.h> #include <Xm/Label.h> #include <stdlib.h> double (*sml_hypot) (double x, double y); void c_main (void) { double a, b, c; a = 3.0; b = 4.0; printf("a = %.6f\n", a); printf("b = %.6f\n", b); c = sml_hypot (a, b); /* call back to SML! */ printf("c = %.6f\n", c); fflush(stdout); char msg[256]; sprintf(msg,"c = %.6f\n", c); Widget shell; XtAppContext app; XmString xmstr; int argc = 1; char* argv[] = {"polygui" }; shell = XtAppInitialize ( &app, "Memo", NULL, 0, &argc, argv, NULL, NULL, 0 ); xmstr = XmStringCreateLtoR ( msg, XmFONTLIST_DEFAULT_TAG ); XtVaCreateManagedWidget ( "message", xmLabelWidgetClass, shell, XmNlabelString, xmstr, NULL ); XmStringFree ( xmstr ); XtRealizeWidget ( shell ); XtAppMainLoop ( app ); return; } On Thu, Jan 22, 2015 at 4:00 AM, <polyml-request at inf.ed.ac.uk> wrote: > Send polyml mailing list submissions to > polyml at inf.ed.ac.uk > > To subscribe or unsubscribe via the World Wide Web, visit > http://lists.inf.ed.ac.uk/mailman/listinfo/polyml > or, via email, send a message with subject or body 'help' to > polyml-request at inf.ed.ac.uk > > You can reach the person managing the list at > polyml-owner at inf.ed.ac.uk > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of polyml digest..." > > > Today's Topics: > > 1. Re: linking polyML modules to C (Phil Clayton) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Wed, 21 Jan 2015 20:20:06 +0000 > From: Phil Clayton <phil.clayton at veonix.com> > To: polyml at inf.ed.ac.uk > Subject: Re: [polyml] linking polyML modules to C > Message-ID: <54C009F6.1050209 at veonix.com> > Content-Type: text/plain; charset="iso-8859-1"; Format="flowed" > > 19/01/15 12:19, David Matthews wrote: > > On 19/01/2015 04:34, David Topham wrote: > >> Thanks David for your response. > >> > >> While searching I found this comment you made earlier: > >> > >> "The foreign-function interface allows for call-back functions so > >> there is > >> the mechanism to produce a C function that when called calls an ML > >> function." > >> > >> in > >> http://stackoverflow.com/questions/17580386/shared-libraries-in-poly-ml > >> > >> Doesn't this indicate a mechanism that allows an SML function to be > >> called > >> from C? > > > > Yes, but the "main program" still has to be in ML. You can call C > > library functions and pass an ML function as an argument. > > Or the ML functions can be passed via global variables that are > initialized from the ML side - see attached example. That may be easier > if there are a large number of ML functions. > > > > Actually, I did wonder whether this could be used as a way of exporting > > ML functions to create a library that could be called from a C main > > program and came to the conclusion that it was going to be too > > complicated. Poly/ML uses libffi to interface with C. libffi can build > > closures that wrap around ML functions so that these can be passed into > > C. The format of the closure it constructs differs markedly depending > > on the particular architecture since different architectures have > > different calling conventions for C. The closure is a data structure > > with pointers in it. Exporting it would require turning the pointers > > into relocations that the linker/loader will understand. libffi simply > > doesn't provide that information. It's there by implication in the > > source code but not explicitly. > > > > David > > _______________________________________________ > > polyml mailing list > > polyml at inf.ed.ac.uk > > http://lists.inf.ed.ac.uk/mailman/listinfo/polyml > > > >

1 0

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