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Today's Topics:
1. HXT and missing or null values (Ian Knopke)
2. cabal trouble(s!) (Gregory Guthrie)
----------------------------------------------------------------------
Message: 1
Date: Wed, 13 Jun 2012 16:29:32 +0100
From: Ian Knopke <ian.kno...@gmail.com>
Subject: [Haskell-beginners] HXT and missing or null values
To: beginners-requ...@haskell.org, beginners@haskell.org
Message-ID:
<CAC+f4wkJQMYp-N==pp8c3yhinj22yy-znzb1hc-ddamh4fj...@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
I have an xml file I'm trying to parse using HXT. This is the code
(for some reason the list seems to be rejecting the XML example):
data Thing = Thing {first :: String, second :: String}
getThings = atTag "thing" >>>
proc x -> do
first <- text <<< atTag "first" -< x
second <- text <<< atTag "second" -< x
returnA -< Thing {first = first,second = second}
atTag tag = deep (isElem >>> hasName tag)
text = getChildren >>> getText
parseThings str = runX (readString [withValidate no] str >>> getThings)
The problem is that sometimes one of the tags is empty.
I'd like the code to return something like Thing
{first="val",second=""} but instead the entire entry is skipped. Can
someone explain to me what I need to do to get a null or empty string
value inserted instead?
Ian
------------------------------
Message: 2
Date: Wed, 13 Jun 2012 12:23:05 -0500
From: Gregory Guthrie <guth...@mum.edu>
Subject: [Haskell-beginners] cabal trouble(s!)
To: "beginners@haskell.org" <beginners@haskell.org>
Message-ID:
<08ef9da445c4b5439c4733e1f35705ba01a2767cb...@mail.cs.mum.edu>
Content-Type: text/plain; charset="us-ascii"
I have lots of problems with cabal - not sure why or how to correct them.
ghc-pkg check reports tons of issues, but all seem to be haddock-html, which
doesn't sound too serious, or haddock-interfaces.
Warning: haddock-html:
C:\Users\guthrie\AppData\Roaming\cabal\doc\wxdirect-0.90.0.1\html doesn't exist
or isn't a directory
...
Cabal install errors, For example;
C:\Users\guthrie>cabal install gloss-examples
Resolving dependencies...
Configuring gloss-raster-1.7.4.4...
Building gloss-raster-1.7.4.4...
Preprocessing library gloss-raster-1.7.4.4...
[1 of 2] Compiling Graphics.Gloss.Raster.Array (
Graphics\Gloss\Raster\Array.hs, dist\build\Graphics\Gloss\Raster\Array.o )
Warning: Couldn't figure out LLVM version!
Make sure you have installed LLVM
ghc.exe: could not execute: opt
What is LLVM, and do/how I need to install it?
and another (of many) - perhaps unrelated:
C:\Users\guthrie\AppData\Roaming\cabal\bin>cabal install wxc
Resolving dependencies...
<command line>: cannot satisfy -package Cabal-1.10.2.0:
Cabal-1.10.2.0-db589dd5d526d3111ac2fde0f9ab986c is unusable due to missing
or recursive dependencies:
array-0.3.0.2-8e9cd0144e87fa9cc86cc9031631c4f3 base-4.3.1.0-f520cd232cc386
346843c4a12b63f44b containers-0.4.0.0-18deac99a132f04751d862b77aab136e
directory
-1.1.0.0-3a2367d72569467a8af8a231656ff1b8
filepath-1.2.0.0-f132e9f7703da4e20a47f
f2b9acf1ea1 old-time-1.0.0.6-445ce39cbcebd38069c25c0f383b728d
pretty-1.0.1.2-abc
7c632374e50e1c1927987c2651f0f
process-1.0.1.5-b3dded8e54a2e13d22af410bdcfafff4
(use -v for more information)
cabal: Error: some packages failed to install:
wxc-0.90.0.3 failed during the configure step. The exception was:
ExitFailure 1
Trying to resolve them:
C:\Users\guthrie\AppData\Roaming\cabal\bin>cabal install base
Resolving dependencies...
cabal: internal error: impossible
I've had several others, not sure if they are package specific issues, or some
larger issue with cabal and libraries.
So I tried to fix them from a suggestion in SO; delete the ~/ghc & ~/cabal
files and restart cabal, by a "cabal install cabal-install".
It gives:
C:\Users\guthrie>cabal install cabal-install
Resolving dependencies...
In order, the following would be installed:
deepseq-1.3.0.0 (reinstall) changes: array-0.4.0.0 -> 0.3.0.3
containers-0.4.2.1 (reinstall) changes: array-0.4.0.0 -> 0.3.0.3
old-time-1.0.0.7 (new version)
directory-1.1.0.2 (reinstall) changes: filepath-1.3.0.0 -> 1.2.0.1,
old-time-1.1.0.0 -> 1.0.0.7
...
cabal: The following packages are likely to be broken by the reinstalls:
time-1.4
wxdirect-0.90.0.1
random-1.0.1.1
haskell-platform-2012.2.0.0
QuickCheck-2.4.2
...
ghc-7.4.1
...
Cabal-1.14.0
process-1.1.0.1
haskell98-1.1.0.1
haskell-src-1.0.1.4
haskell-platform-2011.2.0.1
haskell-src-1.0.1.4
haskell-platform-2011.3.0.0
ghc-7.0.4
Use --force-reinstalls if you want to install anyway.
Lots of things there that I don't want to break, but not sure how to proceed.
Even trying a -force-reinstall just gives more errors and failures...
Running ghc 7.4.1, and Haskell platform 2012.2.0.0, cabal reports:
cabal-install version 0.14.0, using version 1.14.0 of the Cabal library.
------------------------------
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