How do I find the source of the code I am importing. Like if I do
λ <Prelude>: import Graphics.EasyPlot
λ <Prelude Graphics.EasyPlot>:
How do I find that code. I do not mean an online copy of the code (Google is very good at indexing Hackage by that) but where it is on my system that I can edit. The reason is that it is a bit buggy, and I want to try and fix it. (I might submit a patch, but I just want to fix it for my own use first.)
As #ThomasDuBuisson mentioned, you many not necessarily find that on your system. One thing which I generally do is fetch it using cabal:
cabal fetch package-name
It downloads the tarballs of the package. Once you have fetched it, the entire source will be under the path where cabal puts it. In my case, it is (/home/sibi/.cabal/packages/hackage.haskell.org/package-name ). You can then untar and then build it from the cabal file which is already present there.
That being said you should probably using the version control system which the project is using as #bheklilr pointed out.
Related
I need the source package for the mingw64/mingw-w64-x86_64-gcc-libs-8.2.0-3 package. I believe this is generated from the mingw-w64-x86_64-gcc source package. Looking in the repository I can find mingw-w64-gcc-7.3.0-2.src.tar.gz but nothing for gcc-8.*.
Most other packages have a simple relationship between binary and source package names. In a few cases (GCC is one) a single source package is used to generate multiple binary packages. However the naming is usually fairly obvious, and version numbers stay the same. I can't find any GCC-related source packages with the "8.2.0" version number.
Does anyone know where to get the source for the gcc-libs mingw package from?
You might want to look at here. You can find GCC 8.1.0.
Open an issue on https://github.com/Alexpux/MINGW-packages/issues
Apparently the maintainer forgot to upload the source package, or some script is failing.
I recently made a cabal package which can be seen here
It consists of a library and a few small example programs using it. Everything builds and works as expected.
I wanted to build an executable in a new package which uses this library, however I continue to run into a linking error I can't decipher:
/my/path/RandomAgent/.cabal-sandbox/lib/x86_64-linux-ghc-7.8.4/rlglue-0.2.1.1/libHSrlglue-0.2.1.1.a(Agent.o):(.text+0x34f1): undefined reference to `rlgluezm0zi2zi1zi1_Pathszurlglue_version1_closure'
collect2: error: ld returned 1 exit status
To make things simpler to diagnose I moved one of the examples programs into my new package and discovered even it won't build properly. You can find that version of the executable here.
From this I've concluded that the problem is likely in something I'm doing in my .cabal files, but I can't see what's wrong. The error also seems to refer to the Paths_rlglue module which cabal automatically generates for the first package.
Can anyone help me understand why I'm getting this error?
You need to include the Paths_rlglue module in exposed-modules or other-modules like any other module in your project so that Cabal will link it.
Cabal should be better about telling you what is going on, see https://github.com/haskell/cabal/issues/1746.
Looks like I missed something in the documentation for Paths_pkgname
If you decide to import the Paths_pkgname module then it must be
listed in the other-modules field just like any other module in your
package.
Adding Paths_rlglue to my library's other-modules fixed the issue. Hope this saves someone all the time I lost on this.
I have developed a module (M.hs) which depends upon 3 other modules (A.hs, B.hs and C.hs). Now I want to use the module M across multiple other projects. So I have to install this module. But for learning purpose I don't want to use cabal, I want to do it manually. I want to install it in my home dir.
What is a proper course of action? Which files to be created, copied? where? How to use this module in other project?
Additional info:
I am using Debian 6
I am using GHC 6.12
You say you don’t want to use cabal, but would you use Cabal?
cabal is the name of the command line tool provided by cabal-install which can download packages from Hackage and resolve dependencies.
Cabal is the library that Haskell code uses to drive the compilation (e.g. pre-process files, build in the right order, build variants, generate documentation) and install into the right location.
I would not recommend not using Cabal, even for learning purposes, until you want to write a replacement for it. But if you really want to do it, here is the rough outline, with enough details to figure out for a good learning experience:
Build your files with -package-name yourpkgname-version.
Link the generated files to form a libyourpkgname-version.a file.
Create a package configuration file like /var/lib/ghc/package.conf.d/mtl-2.1.2.conf, and pay attention to name, `exposed-modules, import-dirs, library-dirs and hs-libraries
Register package by passing it to ghc-pkg register
The ~/.cabal/config stores configuration which cabal-install uses. I wanted to do some hackery on it. (Specifically, having multiple GHC versions installed, I wish to have separate documentation indexes).
I couldn't, however, find any documentation about its' syntax or variables except for what is included in default file. Is there any documentation available?
Edit: I've stated the goal above, but let me add some details: If the same package (eg. GTK) is installed in two versions of GHC they end up in the same documentation index file. I wan't that local documentation index to be separate for each GHC installation. I believe it is possible in some way using documentation directory setting, but there has to be a variable for currently used GHC version. If there isn't one there might be some workarounds available, but I won't be able to say that unless I see the documentation.
This seems to work, although I've only tested it with one version of GHC:
documentation: True
doc-index-file: $datadir/doc/$compiler/index.html
install-dirs user
docdir: $datadir/doc/$compiler/$pkgid
With the other options left at the default, this generates documentation in .cabal/share/doc/<ghc-version>/<package-name>, and the index in .cabal/share/doc/<ghc-version>/index.html.
There appears to be very little online - not even the haddocks for the cabal-install code. So your best bet may be to puzzle it out from the source. cabal unpack cabal-install, or view the cabal-install repo online. Look at SavedConfig in Distribution/Client/Config.hs. As an example, it imports GlobalFlags from Setup.hs; the individual flags, eg globalCacheDir, are associated with their config-file syntax (which is also the command-line syntax) in the globalCommand function below, remote-repo-cache in this case.
You should also ask dcoutts in the #haskell channel on irc.freenode.net, in case he has new docs available.
I am trying to build an application with OpenSync 0.4 (0.3.9 indeed) dependency.
In the project's configure.ac the opensync library is written as libopensync1. However, this doesn't build on my Gentoo system. Changing libopensync1 to libopensync does fix the issue for me.
I searched with Google and found that libopensync1 is used in some distributions, while libopensync in others. So how to resolve this issue in configure.ac?
Thanks.
The macro AC_SEARCH_LIBS does what you need. (There is much heated debate about whether or not pkg-config should ever be used. If you choose to rely on it, ptomato gives a reasonable approach.) Simply add this to your configure.ac:
AC_SEARCH_LIBS([osync_mapping_new],[opensync1 opensync],[],
[AC_MSG_ERROR([can't find opensync])])
This will first look for a library named opensync1; if
it doesn't find that, it will look for opensync.
The primary drawback of using pkg-config is that most projects that
rely on it do not actually check if the data provided by the .pc
file is reliable, so configure may succeed but a subsequent build
will fail. It is always possible for a user to set PKG_CONFIG=true
when running configure and completely eliminate all of the data
provided by any associated .pc files, setting LIBS, CFLAGS, etc by
hand the 'old-fashioned' way.
The primary drawback of not using pkg-config is that the user
has to set LIBS, CFLAGS, etc. the old-fashioned way. In practice,
this is pretty trivial, and all pkg-config has done is move the
data from a single CONFIG_SITE file to separately maintained
.pc files for each package.
If you do use PKG_MODULE_CHECK, follow it up with a call to
AC_CHECK_LIB or AC_SEARCH_LIBS to validate the data in whatever
.pc file was located by PKG_CHECK_MODULES
I'm assuming that the place at which this occurs inside your configure.ac is inside a PKG_CHECK_MODULES call.
Looking at the libopensync sources, it seems that libopensync1 is the newer name, and libopensync is the old name. So, we'll use pkg-config macros to look for the newer name unless it doesn't exist.
Put this in your configure.ac:
# Check if libopensync1 is known to pkg-config, and if not, look for libopensync instead
PKG_CHECK_EXISTS([libopensync1], [OPENSYNC=libopensync1], [OPENSYNC=libopensync])
Then later in your PKG_CHECK_MODULES call, replace libopensync1 with $OPENSYNC.