Poly/ML

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704 discussions

printing out references
by Michael.Norrish＠nicta.com.au 28 Nov '08

28 Nov '08

How can I prettyprint a reference value so that I get some idea from looking at the output whether two such values are the same or not? I have a data type that is littered with various references, and the default pretty-printer only gives me strings with "ref" through them. If I have "ref 1" in one place and "ref 1" in another, I have no idea whether or not these are the same references. If I want to handle this situation in pure SML, it seems as if I'd have to maintain a global list of seen references and look each reference up by doing a linear search through the list. This is pretty awful. Even if there was a Ref.compare function so that I could avoid linear search, the table would still need to be global so that successive pretty-prints would continue to make sense with respect to each other. In Moscow ML there is an Obj.magic function that will turn anything into anything, and in particular seems happy to turn a ref into an integer. Is there something comparable in Poly/ML? (I browsed the poly sources in a very cursory fashion and discovered RunCall.unsafeCast, but this either gave me a segmentation fault, or seemed to be looking at the values at the other ends of the references when I applied it to them.) Michael.

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Unable to allocate immutable area
by thomas.ridge＠cl.cam.ac.uk 18 Nov '08

18 Nov '08

Dear All, I am using polyml to run hol. >From within emacs, I normally use "C-c C-r" to send a region to the hol process. This involves emacs writing out to a tmp file, and the hol process attempting to "use" the file back in. After a lot of proof, I get the following error: "Unable to allocate immutable area" which occurs in the "use" command. Immediately after the above error, I get the following two lines: eg Failed to translate file: /tmp/sml26128UHN Exception- Fail "use" raised The result is that I can no longer use "C-c C-r" to send a file (nor, presumably, "use" any other file). I can still cut and paste into the hol process buffer. What does the error mean? Can I do anything to improve things? Thanks Tom

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obscure segfault
by krauss＠in.tum.de 18 Nov '08

18 Nov '08

Dear list, The following code leads to a segmentation fault when fed into polyml: fun REPEAT t r c = REPEAT t c (t r c); fun I x = x; fun f r c n = if n <= 0 then r n else c n; fun g x = REPEAT f I I x; g 0; The code really doesn't make any sense... but assuming that polyml should never segfault, this must be a bug. Any ideas why this occurs? Does it have to do with the value restriction in some form? Thanks, Alex

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library path-related installation problems with Poly/ML 5.2.1 on Windows XP Professional, Service Pack 2
by DekuDekuplex＠Yahoo.com 12 Nov '08

12 Nov '08

I am trying to install Poly/ML 5.2.1 from source on Windows XP Professional, Service Pack 2, but apparently "make" is having difficulties in finding the library path. Apparently, /usr/local/lib is not in the library search path. I tried overriding this by specifying >./configure --prefix=/usr when running "./configure," but this didn't help. As a result, polyml is unable to build the sample hello program. In the following example of building an application: >$ poly >Poly/ML 5.0 Release >> fun f () = print "Hello World\n"; >val f = fn : unit -> unit >> PolyML.export("hello", f); >val it = () : unit >> ^D >$ cc -o hello hello.o -lpolymain -lpolyml >$ ./hello >Hello World hello.o is built, but there is no file "hello" or "hello.exe" to execute. Apparently, this problem occurs because of the following error messages that appeared while running "make": >*** Warning: linker path does not have real file for library -lgdi32. >*** I have the capability to make that library automatically link in when >*** you link to this library. But I can only do this if you have a >*** shared version of the library, which you do not appear to have >*** because I did check the linker path looking for a file starting >*** with libgdi32 and none of the candidates passed a file format test >*** using a file magic. Last file checked: /lib/w32api/libgdi32.a > >*** Warning: linker path does not have real file for library -lwsock32. >*** I have the capability to make that library automatically link in when >*** you link to this library. But I can only do this if you have a >*** shared version of the library, which you do not appear to have >*** because I did check the linker path looking for a file starting >*** with libwsock32 and none of the candidates passed a file format test >*** using a file magic. Last file checked: /lib/w32api/libwsock32.a > >*** Warning: linker path does not have real file for library -lpthread. >*** I have the capability to make that library automatically link in when >*** you link to this library. But I can only do this if you have a >*** shared version of the library, which you do not appear to have >*** because I did check the linker path looking for a file starting >*** with libpthread and none of the candidates passed a file format test >*** using a file magic. Last file checked: /lib/libpthread.a > >*** Warning: linker path does not have real file for library -ldl. >*** I have the capability to make that library automatically link in when >*** you link to this library. But I can only do this if you have a >*** shared version of the library, which you do not appear to have >*** because I did check the linker path looking for a file starting >*** with libdl and none of the candidates passed a file format test >*** using a file magic. Last file checked: /lib/libdl.a >*** The inter-library dependencies that have been dropped here will be >*** automatically added whenever a program is linked with this library >*** or is declared to -dlopen it. > >*** Since this library must not contain undefined symbols, >*** because either the platform does not support them or >*** it was explicitly requested with -no-undefined, >*** libtool will only create a static version of it. Any ideas on how to overcome this installation problem? -- Benjamin L. Russell

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Release 5.2.1
by David.Matthews＠prolingua.co.uk 23 Oct '08

23 Oct '08

Philip Clayton wrote: > Thanks for the new version. Just in case it was unintentional, I > thought I should let you know that the .tar.gz file contains a directory > 'polyml', rather than 'polyml.5.2.1' as has been the convention for > previous releases. Thanks for pointing that out. It was unintentional and I've now updated the site. It may take a while for the mirrors to pick up the new version but it should eventually make its way through. David

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Release 5.2.1
by David.Matthews＠prolingua.co.uk 22 Oct '08

22 Oct '08

I've now released version 5.2.1 of Poly/ML on the SourceForge site. This is largely a bug-fix release of 5.2 and incorporates various fixes to the run-time system and basis library. I'll update the release notes on the web site with details of the bug fixes. The functional IO library has been largely rewritten to be much more efficient. One change that may affect a few people is that X-Windows/Motif support is now turned off by default in the configure script. To include support for X-Windows/Motif specify --with-x when running "configure" Note: Since the compiler has not changed when you run Poly/ML 5.2.1 the start-up line will still say "Poly/ML 5.2 Release". However poly -v will say something like Poly/ML 5.2 Release RTS version: I386-5.2.1 David

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Garbage collection issue with functional input streams
by pclayton＠taz.qinetiq.com 16 Sep '08

16 Sep '08

I have found a performance issue when using TextIO.StreamIO.input1 to read a functional stream. Looking at gc/non-gc times and using PolyML.profiling, it appears that garbage collection accounts for most of the time. There is some code below to demonstrate with stats that include comparison with SML/NJ. The profiling shows that readFromReader in basis/BasicStreamIO.sml is responsible for creating values that are being garbage collected. Looking at this code, I can see various things that would contribute to this garbage collection but nothing that is obviously problematic. Is it simply the case that overheads in the implementation mean that it is not suitable for a large number of small reads? Thanks, Phil (* `makeTextFile (filename, length)` generates a text file *) (* called `filename` of length `length` where every character *) (* is the digit '0'. *) local val l = 2048; val s = implode (List.tabulate (l, fn _ => #"0")); in fun makeTextFile (filename, length) = let open TextIO; val ostream = getOutstream (openOut filename); fun write n = if n < l then StreamIO.output (ostream, String.substring (s, 0, n)) else (StreamIO.output (ostream, s); write (n - l)); in write length; StreamIO.closeOut ostream end; end; (* `readTextFile filename` reads the file called `filename` *) (* one character at a time using a functional input stream *) (* and returns the time taken to read it. *) fun readTextFile filename = let open TextIO; val src = getInstream (openIn filename); fun read src = case StreamIO.input1 src of SOME (_, src') => read src' | NONE => (); val startTime = Timer.startCPUTimer (); in read src; (fn {sys, usr} => Time.+ (sys, usr)) (Timer.checkCPUTimer startTime) before StreamIO.closeIn src end; (* Create files and then read *) makeTextFile ("text-01MB", 1024 * 1024 * 1); makeTextFile ("text-02MB", 1024 * 1024 * 2); makeTextFile ("text-03MB", 1024 * 1024 * 3); makeTextFile ("text-04MB", 1024 * 1024 * 4); makeTextFile ("text-05MB", 1024 * 1024 * 5); readTextFile "text-01MB"; readTextFile "text-02MB"; readTextFile "text-03MB"; readTextFile "text-04MB"; readTextFile "text-05MB"; (* read times in seconds on Intel Core 2 Duo CPU T7500 @ 2.20GHz, 2GB *) (* Poly/ML 4.1.3 Poly/ML 5.2 SML/NJ 110.52 text-01MB 0.7 - 0.8 0.3 - 1.5 0.03 - 0.05 text-02MB 2.2 - 2.3 1.9 - 2.8 0.06 - 0.09 text-03MB 4.3 - 4.5 2.0 - 4.3 0.08 - 0.14 text-04MB 7.2 - 7.5 4.2 - 6.6 0.11 - 0.16 text-05MB 11.0 - 11.1 4.0 - 5.8 0.14 - 0.18 *) (* for large files, Poly/ML 4.1.3 can run out of store: *) makeTextFile ("text-40MB", 1024 * 1024 * 40); readTextFile "text-40MB"; (* Poly/ML 4.1.3 Poly/ML 5.2 SML/NJ 110.52 text-40MB out of store 101.4 1.1 - 1.2 4.1.3 gives the following message: Run out of store - interrupting console processes Exception- Interrupt raised *) The information contained in this E-Mail and any subsequent correspondence is private and is intended solely for the intended recipient(s). The information in this communication may be confidential and/or legally privileged. Nothing in this e-mail is intended to conclude a contract on behalf of QinetiQ or make QinetiQ subject to any other legally binding commitments, unless the e-mail contains an express statement to the contrary or incorporates a formal Purchase Order. For those other than the recipient any disclosure, copying, distribution, or any action taken or omitted to be taken in reliance on such information is prohibited and may be unlawful. Emails and other electronic communication with QinetiQ may be monitored and recorded for business purposes including security, audit and archival purposes. Any response to this email indicates consent to this. Telephone calls to QinetiQ may be monitored or recorded for quality control, security and other business purposes. QinetiQ Limited Registered in England & Wales: Company Number:3796233 Registered office: 85 Buckingham Gate, London SW1E 6PD, United Kingdom Trading address: Cody Technology Park, Cody Building, Ively Road, Farnborough, Hampshire, GU14 0LX, United Kingdom http://www.QinetiQ.com/home/legal.html

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Re: Poly/ML 5.2 and signals on older Linux systems
by David.Matthews＠prolingua.co.uk 09 Sep '08

09 Sep '08

Rob Arthan wrote: > David, > However, while I agree that my "fix" is a hack because it's working around > what looks like a bug in the old glibc, I am a little concerned that your > signal handling design is not POSIX-conformant. The POSIX specification of > sigaction includes the following statement: > > "The result of the use of sigaction() and a sigwait() function concurrently > within a process on the same signal is unspecified." > > I take this to mean that if you change the disposition of a signal using > sigaction() while you are waiting for it with sigwait() then the result is > unspecified. So the Cygwin behaviour would be conformant. The documentation > on signal() doesn't say anything about sigwait(), but it does say: > > "Use of this function is unspecified in a multi-threaded process." > > I think the POSIX-compliant way of implementing the ML signal function would > be to service ML requests to change the disposition of a signal by waking up > the signal detection thread and having it call sigaction. Thanks for pointing this out. I've also had another look at the documentation for sigwait and discovered that the Cygwin behaviour might be acceptable, not because of the interaction with sigaction but because the behaviour of sigwait when a signal is not blocked is undefined. As a result of all this I've revisited the whole mechanism for signal handling. The difficulty is that the pthread mutex and condition variable functions are not safe when used in a signal handler but it turns out that POSIX sem_post is safe. I've reworked the code to use a signal handler rather than sigwait and this appears to work on all the platforms I've tried, with the inevitable tweaks for the peculiarities of semaphores on Mac OS X and Cygwin. The new version is in CVS so you can try it out if you wish. I still have to get to the bottom of the other bug. Regards, David Copied to the mailing list for information.

2 2

InternalError: getSome raised while compiling
by tbourke＠cse.unsw.edu.au 28 Aug '08

28 Aug '08

I have a program that causes an InternalError in Poly/ML 5.2 on FreeBSD (but not MLton or SML/NJ). I haven't been able to test it under Linux. It can be reduced to these declarations: type int = Int.int; signature SIG = sig datatype t1 = T1 of int datatype t2 = T2 of { f : t1 } end; functor Fun () : SIG = struct datatype t1 = T1 of int datatype t2 = T2 of { f : t1 } end; structure Str1 = Fun () (*;*) structure Str2 : SIG = struct open Str1 end; fun g (Str2.T2 {f}) = (f=f); They compile if any of various changes are made: such as adding the semi-colon suggested above, removing the type int declaration, trying to shortcut Str2, removing the T1 label. Unfortunately, the corresponding changes are either difficult to make in the original program or do not seem to fix the problem. Sorry I haven't yet had time to look at Poly/ML myself. If a solution isn't readily suggested, I'll try to look harder over the weekend. Tim.

1 0

Unicode in Poly/ML?
by Michael.Norrish＠nicta.com.au 21 Aug '08

21 Aug '08

It is possible to emit Unicode (UTF-8 encoded say) strings in a Poly/ML program by emitting the appropriate sequence of bytes: Poly/ML 5.2 Release > print "\u00e2\u0088\u0080\n"; ? val it = () : unit But as far as Poly is concerned, this is actually a sequence of four characters, not two (the universal quantifier and the newline). Are there any plans to implement some sort of sensible WideChar signature? (The existing WideChar signature in the Basis is not really a good base on which to build good support here.) Michael.

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