Haskell HXT Pickle

Question

我刚刚使用 XML 的“hxt”包编写了一个简单的程序:

module Main(main,pickle)    where

import qualified    Text.XML.HXT.Arrow.Pickle   as HXT.Arrow.Pickle
import qualified    Text.XML.HXT.Arrow.Pickle.Xml   as HXT.Arrow.Pickle.Xml
import qualified    Text.XML.HXT.Core       as HXT.Core
import qualified    System.Environment

newtype Subject = MkSubject Int deriving (Read, Show)

instance HXT.Arrow.Pickle.XmlPickler Subject    where
    xpickle = xpSubject

xpSubject :: HXT.Arrow.Pickle.Xml.PU Subject
xpSubject   = HXT.Arrow.Pickle.xpElem "Subject" . HXT.Arrow.Pickle.xpWrap (
    MkSubject,
    \(MkSubject x)  -> x
 ) . HXT.Arrow.Pickle.xpAttr "Topic" $ HXT.Arrow.Pickle.xpPrim

pickle :: String -> IO ()
pickle srcFilePath = HXT.Core.runX (
    HXT.Core.xunpickleDocument xpSubject [
        HXT.Core.withValidate HXT.Core.yes,
        HXT.Core.withTrace maxBound,
        HXT.Core.withRemoveWS HXT.Core.yes,
        HXT.Core.withPreserveComment HXT.Core.yes
    ] srcFilePath
 ) >> return ()

main :: IO ()
main    = pickle =<< fmap head System.Environment.getArgs

在 OpenSuSE-11.4 上编译此代码，使用 ghc-7.4.1 可以正常工作:

$ ghc Main.hs
[1 of 1] Compiling Main             ( Main.hs, Main.o )
Linking Main ...

在示例 XML 文件上运行会导致无限循环:

$ ./Main subject.xml 
-- (1) readDocument: start processing document "subject.xml"
-- (2) setDefaultBaseURI: new default base URI is "file:///home/al/Documents/Software/Haskell/Test/"
-- (2) setBaseURI: new base URI is "file:///home/al/Documents/Software/Haskell/Test/"
-- (2) setBaseURI: new base URI is "file:///home/al/Documents/Software/Haskell/Test/subject.xml"
-- (2) getURIContents: reading "file:///home/al/Documents/Software/Haskell/Test/subject.xml"
-- (2) read file "/home/al/Documents/Software/Haskell/Test/subject.xml" (strict input = False)
-- (2) decodeDocument: encoding is "ISO-8859-15"
-- (1) getXmlContents: content read and decoded for "file:///home/al/Documents/Software/Haskell/Test/subject.xml"
-- (1) getXmlContents'


content of: subject.xml
=======================

---XTag "/"
   |   "version"="1.0"
   |   "encoding"="ISO-8859-15"
   |   "transfer-MimeType"="text/xml"
   |   "transfer-Status"="200"
   |   "transfer-Message"="OK"
   |   "transfer-URI"="file:///home/al/Documents/Software/Haskell/Test/subject.xml"
   |   "source"="subject.xml"
   |   "transfer-Encoding"="ISO-8859-15"
   |
   +---XText "<?xml version=\"1.0\" encoding=\"ISO-8859-15\"?>\n\n<!-- An example of the specification in XML, of the problem-parameters -->\n\n<Subject Topic=\"test\"/>\n\n<!-- End -->\n\n"


-- (1) readDocument: "subject.xml" (mime type: "text/xml" ) will be processed
-- (2) checkUndefinedEntityRefs: looking for undefined entity refs
-- (2) checkUndefinedEntityRefs: looking for undefined entity refs done
-- (1) readDocument: "subject.xml" processed
<!-- An example of the specification in XML, of the problem-parameters -->
<Subject Topic="test"/>
<!-- End -->


content of: subject.xml
=======================

---XTag "/"
   |   "version"="1.0"
   |   "encoding"="ISO-8859-15"
   |   "transfer-MimeType"="text/xml"
   |   "transfer-Status"="200"
   |   "transfer-Message"="OK"
   |   "transfer-URI"="file:///home/al/Documents/Software/Haskell/Test/subject.xml"
   |   "source"="subject.xml"
   |   "transfer-Encoding"="ISO-8859-15"
   |
   +---XCmt " An example of the specification in XML, of the problem-parameters "
   |
   +---XTag "Subject"
   |   |   "Topic"="test"
   |
   +---XCmt " End "



fatal error: document unpickling failed
xpPrim: reading string "test" failed
context:    Main: <<loop>>

当然，这是我第一次使用“hxt”，我怀疑这是一个根本性的错误......但打包的示例代码表现出相同的行为:

$ cd ~/.cabal/packages/hackage.haskell.org/hxt/9.2.2/hxt-9.2.2/examples/arrows/pickle
$ make
ghc -Wall -O2  --make -o pickleTest PickleTest.hs
[1 of 1] Compiling Main             ( PickleTest.hs, PickleTest.o )
Linking pickleTest ...
make: *** No rule to make target `PickleTestWithNamespaces.hs', needed by `pickleTestWithNamespaces'.  Stop.

$ ./pickleTest 
### Error in:   0:pickle/unpickle tests with example programs:0:0
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:0:1
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:0:2
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:0:3
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:0:4
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:0:5
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:1:0
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:1:1
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:1:2
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:1:3
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:1:4
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:1:5
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:2:0
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:2:1
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:2:2
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:2:3
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:2:4
<<loop>>
### Error in:   0:pickle/unpickle tests with example programs:2:5
<<loop>>
Cases: 18  Tried: 18  Errors: 18  Failures: 0
Counts {cases = 18, tried = 18, errors = 18, failures = 0}

我怀疑这是软件包的一些不匹配:

$ ghc-pkg list
/usr/local/lib/ghc-7.4.1/package.conf.d
   Cabal-1.14.0
   array-0.4.0.0
   base-4.5.0.0
   bin-package-db-0.0.0.0
   binary-0.5.1.0
   bytestring-0.9.2.1
   containers-0.4.2.1
   deepseq-1.3.0.0
   directory-1.1.0.2
   extensible-exceptions-0.1.1.4
   filepath-1.3.0.0
   ghc-7.4.1
   ghc-prim-0.2.0.0
   haskell2010-1.1.0.1
   haskell98-2.0.0.1
   hoopl-3.8.7.3
   hpc-0.5.1.1
   integer-gmp-0.4.0.0
   old-locale-1.0.0.4
   old-time-1.1.0.0
   pretty-1.1.1.0
   process-1.1.0.1
   rts-1.0
   template-haskell-2.7.0.0
   time-1.4
   unix-2.5.1.0
/home/al/.ghc/x86_64-linux-7.4.1/package.conf.d
   HTTP-4000.2.3
   HUnit-1.2.4.2
   QuickCheck-2.4.2
   cpphs-1.13.3
   dotgen-0.4.1
   hashable-1.1.2.3
   haskell-lexer-1.0
   haskell-src-exts-1.13.0
   hlint-1.8.28
   hscolour-1.19
   html-1.0.1.2
   hxt-9.2.2
   hxt-charproperties-9.1.1
   hxt-regex-xmlschema-9.0.4
   hxt-unicode-9.0.2
   mtl-2.1
   network-2.3.0.13
   parallel-3.2.0.2
   parsec-3.1.2
   primes-0.2.1.0
   random-1.0.1.1
   regex-base-0.93.2
   regex-posix-0.95.1
   syb-0.3.6
   text-0.11.2.0
   transformers-0.3.0.0
   uniplate-1.6.7
   unordered-containers-0.2.1.0
   xhtml-3000.2.0.5
   zlib-0.5.3.3

感谢您提前提供的任何帮助。

Answer 1

尝试在没有优化/规则的情况下安装 hxt，看看错误是否仍然发生。

如果没有，您就遇到了这个错误:http://hackage.haskell.org/trac/ghc/ticket/2722