I want to use in my haskell project xml library (http://hackage.haskell.org/package/xml)
I downloaded it.then try to build and install:
runhaskell Setup.hs configure
runhaskell Setup.hs build
runhaskell Setup.hs install
All ok. There are no errors. When i try import modules from this lib to my project, for example:
import Text.XML.Light.Cursor
I get error:
/home/shk/dev/src/XMPP.hs:8:8:
Could not find module `Text.XML.Light.Cursor':
Use -v to see a list of the files searched for.
Failed, modules loaded: none.
What's wrong? How can i install and use library in haskell?
Thank you.
Copying from the mailing list:
First thing is to do 'ghc-pkg list'. If your package doesn't show up
then it's not installed, according to the package registry. 'cabal
install' should have registered it. If it is in the list, then it
depends how you're building. If you use ghc manually, then you have
to give '-package xyz'. If you use 'ghc --make', ghc will
automatically add the -package for you. If you use cabal, you put the
package in the dependencies, and 'cabal build' will add -package for
you.
If the package has parens, then someone hid it, and you'll have to do
'ghc-pkg expose' on it. If you're doing everything else right and it
still doesn't find the package, then you can run ghc -v and it'll
print lots of details. It might have something about 'hiding xyz
because of ', which means you're depending on
libraries that expect different versions of the underlying library.
You can sometimes get out of this by carefully upgrading or
downgrading certain libraries.
Related
I installed the timezone-series Haskell module using cabal install timezone-series-0.1.5.1.
I then defined a module named Main.hs that starts with:
import Data.Time.LocalTime.TimeZone.Series -- from timezone-series-0.1.5.1
when I run ghc Main.hs, GHC throws the following error:
/home/ubuntu/Main.hs:2:1: error:
Failed to load interface for ‘Data.Time.LocalTime.TimeZone.Olson’
I tried explicitly including the cabal directory in GHC's search path using:
ghc -i/home/ubuntu/.cabal/lib/x86_64-linux-ghc-8.0.2/timezone-olson-0.2.0-KqRNJj3zomR7zz2Yx6P5Oq/ Main.hs
This resulted in the correct path being searched, but GHC is only looking for files ending in the suffix ".hs":
Locations searched:
...
/home/ubuntu/.cabal/lib/x86_64-linux-ghc-8.0.2/timezone-olson-0.2.0-KqRNJj3zomR7zz2Yx6P5Oq/Data/Time/LocalTime/TimeZone/Series.hs
/home/ubuntu/.cabal/lib/x86_64-linux-ghc-8.0.2/timezone-olson-0.2.0-KqRNJj3zomR7zz2Yx6P5Oq/Data/Time/LocalTime/TimeZone/Series.lhs
/home/ubuntu/.cabal/lib/x86_64-linux-ghc-8.0.2/timezone-olson-0.2.0-KqRNJj3zomR7zz2Yx6P5Oq/Data/Time/LocalTime/TimeZone/Series.hsig
/home/ubuntu/.cabal/lib/x86_64-linux-ghc-8.0.2/timezone-olson-0.2.0-KqRNJj3zomR7zz2Yx6P5Oq/Data/Time/LocalTime/TimeZone/Series.lhsig
Cabal installed interface files instead however:
/home/ubuntu/.cabal/lib/x86_64-linux-ghc-8.0.2/timezone-olson-0.2.0-KqRNJj3zomR7zz2Yx6P5Oq/Data/Time/LocalTime/TimeZone/Olson.hi
From line 318 of GHC's source code it looks like GHC ignores "*.hi" files unless it is called in single-shot mode (with the -c flag). Is this correct? (See: https://github.com/ghc/ghc/blob/67a5a91ef5e61f3b3c84481d8a396ed48cd5d96e/compiler/GHC/Unit/Finder.hs)
How can I get GHC to import this module?
An help will be greatly appreciated!
My suggested ways of installing packages in order of my preference:
Make a cabal package and add timezone-series you want to install to the build-depends field as described in the cabal manual.
Use the experimental cabal-env tool to basically automate the process of point 3 below, but then with the global environment. This makes a new build-plan every time you install a new package, so it is like removing the package environment and building it again with all the old packages and the new package added to it. You can add specific constraints like this: cabal-env "timezone-series == 0.1.5.1".
Install a package into local package environment with cabal --package-env . --lib timezone-series. You can add as many packages as you want after the --lib option to install more than one package. If you later want to use a different set of packages simply remove the .ghc.environment.* file that is generated and rerun the installation with a new set of packages. GHC will automatically use these package environment files that are in the current or parent directories. You can specify specific constraints with the --constraint option like this: --constraint "timezone-series == 0.1.5.1".
Use cabal install --lib timezone-series to install it directly into the global environment (~/.ghc/x86_64-linux-8.0.2/environments/default), this will fail if a conflicting package was installed earlier. When you run into errors you can remove that package environment and try again.
Finally, I want to note that GHC 8.0.2 is quite old, so I would advise you to upgrade if you don't have a specific reason for using that version.
Am working through Real World Haskell and am trying to install regex-posix-0.95.2 from an untar[ed] package by simplying running
cabal install
I then see:
Text/Regex/Posix/Wrap.hsc:141:1: error:
Could not find module ‘Text.Regex.Base.RegexLike’
There are files missing in the ‘regex-base-0.93.2’ package,
try running 'ghc-pkg check'.
Use -v to see a list of the files searched for.
|
141 | import Text.Regex.Base.RegexLike(RegexOptions(..),RegexMaker(..),RegexContext(..),MatchArray)
Despite the fact that I can load this in ghci with
Prelude> :module Text.Regex.Base.RegexLike
Prelude Text.Regex.Base.RegexLike>
Prelude> import Text.Regex.Base.RegexLike(RegexOptions(..),RegexMaker(..),RegexContext(..),MatchArray)
Prelude Text.Regex.Base.RegexLike>
and see it in the module-system.
[warrick#warrick-pc regex-posix-0.95.2]$ ghc-pkg find-module Text.Regex.Base.RegexLike
/usr/lib/ghc-8.6.2/package.conf.d
regex-base-0.93.2
Why is this failing?
What are some more general tips and tricks when trying to debug cabal failures you'd recommend (as this is one instance of many issues I'm consistently having with Cabal)?
This is a linking issue. For example, some distributions like Arch use dynamic linking by default, without static libraries, but without additional configuration, cabal tries to link statically, which results in the kind of message you are seeing. For more information: https://wiki.archlinux.org/index.php/Haskell
I tried importing Data.Numbers.Primes
import Data.Numbers.Primes
runhaskell gave me:
5.hs:1:8:
Could not find module `Data.Numbers.Primes'
Use -v to see a list of the files searched for.
ghci gave me:
<no location info>:
Could not find module `Data.Numbers.Primes'
It is not a module in the current program, or in any known package.
I tried to install Data.Numbers.Primes through cabal, but I got:
cabal update
...
cabal install Data
cabal: There is no package named 'Data'.
You may need to run 'cabal update' to get the latest list of available
packages.
cabal install Data.Numbers.Primes
cabal: The file does not exist 'Data.Numbers.Primes'.
help?
The package you're looking for is called primes.
There's no rule that the package will be called the same as its top-level module name. Typically, packages put themselves under whatever makes sense, but that's pretty much arbitrary. When in doubt, Hackage search helps.
I'm currently trying to use pandoc (as a Haskell module, not as a program) to convert MediaWiki text to other formats.
Let's assume this program:
import Text.Pandoc.Readers.MediaWiki
main = do print "foo"
When using runghc to run it, I get the following error message:
pandock.hs:1:8:
Could not find module `Text.Pandoc.Readers.MediaWiki'
Use -v to see a list of the files searched for.
My first assumption was that pandoc was either not installed or incorrectly installed. Therefore I reinstalled it with --force-reinstalls
$ cabal install pandoc --reinstall
[...]
In order, the following will be installed:
pandoc-1.12.3.1 (reinstall) changes: old-time-1.1.0.1 added
[...]
[32 of 55] Compiling Text.Pandoc.Readers.MediaWiki ( src/Text/Pandoc/Readers/MediaWiki.hs, dist/build/Text/Pandoc/Readers/MediaWiki.o )
[...]
Installing library in
/home/uli/.cabal/lib/x86_64-linux-ghc-7.6.3/pandoc-1.12.3.1
Installing executable(s) in /home/uli/.cabal/bin
Registering pandoc-1.12.3.1...
Installed pandoc-1.12.3.1
The output of runghc -v pandock.hs is quite long, I assume the relevant part is:
*** Chasing dependencies:
Chasing modules from: *pandock.hs
pandock.hs:1:8:
Could not find module `Text.Pandoc.Readers.MediaWiki'
Locations searched:
Text/Pandoc/Readers/MediaWiki.hs
Text/Pandoc/Readers/MediaWiki.lhs
Failed, modules loaded: none.
However, both ~/.cabal/lib/x86_64-linux-ghc-7.6.3/pandoc-1.12.3.1/Text/Pandoc/Readers/Mediawiki/MediaWiki.hi and ~/.cabal/bin/pandoc exist. How can I make GHC properly recognize the cabal-installed package?
Any help will be appreciated!
When trying to reproduce this issue on other computers, only 2 out of 5 computers had this issue. On both of them I installed cabal packages in about the same way and order.
In retrospect I assume this issue arose because of some broken packages wreaking havoc:
$ ghc-pkg check
There are problems in package feed-0.3.9.2:
dependency "xml-1.3.13-dd52b1688e97a3c6cd0aa48dba7b153e" doesn't exist
There are problems in package hxt-9.3.1.3:
dependency "network-2.4.2.2-ea77cdf1bc747bc58308fdeb52745c4d" doesn't exist
There are problems in package hspec-1.8.1.1:
dependency "QuickCheck-2.6-409fcc32c191cd6e04afdebb15869820" doesn't exist
There are problems in package quickcheck-io-0.1.0:
dependency "QuickCheck-2.6-409fcc32c191cd6e04afdebb15869820" doesn't exist
There are problems in package regex-compat-0.95.1:
dependency "regex-base-0.93.2-2023953b859e6f91efe89733d2ef5421" doesn't exist
There are problems in package regex-posix-0.95.2:
dependency "regex-base-0.93.2-2023953b859e6f91efe89733d2ef5421" doesn't exist
There are problems in package hxt-9.3.1.2:
dependency "network-2.4.2.2-ea77cdf1bc747bc58308fdeb52745c4d" doesn't exist
The following packages are broken, either because they have a problem
listed above, or because they depend on a broken package.
feed-0.3.9.2
hxt-9.3.1.3
hspec-1.8.1.1
quickcheck-io-0.1.0
regex-compat-0.95.1
regex-posix-0.95.2
hxt-9.3.1.2
MissingH-1.2.0.2
yesod-test-1.2.1
Note that neither pandoc nor yaml (I installed it after asking the question and had the exact same issues as with pandoc) are listed there.
For users also having a similar problem, please ensure:
The package is installed and you're not inside any sandbox where the package is not installed.
In the directory where you're executing the test script, ensure that there is no Text/Pandoc folder (or equivalent, depending on the package causing the problem
Run your test script with runghc -v to check if it searches the proper directory
ghc-pkg list lists your package as installed, and no packages are broken (use ghc-pkg check to check)
I solved my problem by renaming ~/.cabal and ~/.ghc. Note that I did this lacking a proper solution, I think you should only do this as a last resort.
I'm trying to use http://hackage.haskell.org/package/persistent-1.2.3.0, but after installing it through "cabal install persistent", ghc doesn't find its exposed-modules:
Prelude> import Database.Persist.Types
<no location info>:
Could not find module `Database.Persist.Types'
It is not a module in the current program, or in any known package.
And ghc-pkg works fine:
$ ghc-pkg find-module Database.Persist.Types
/var/lib/ghc/package.conf.d
/home/apsk/.ghc/x86_64-linux-7.6.3/package.conf.d
persistent-1.2.3.0
Am I missing something or is this just a bug with cabal/persistent/ghc? My ghc is 7.6.3, btw.
Also, I've tried with no effect: "ghc-pkg recache"; "ghc-pkg check"; installing previous version; reinstalling with and without "sudo" and/or "--global".
Check that you're not using sandboxes, cabal-dev, hsenv, anything else that can influence ghc in looking for dependencies. Make sure you're using ghc/ghci, and not any wrappers, and that ghc/ghci are not aliased to anything in your shell.
Try to specify the package-db explicitly:
ghci -package-db /home/apsk/.ghc/x86_64-linux-7.6.3/package.conf.d
If you launch ghci with -v, it'll print the (caches of) databases it looks at, like this:
% ghci -v
GHCi, version 7.6.3: http://www.haskell.org/ghc/ :? for help
Glasgow Haskell Compiler, Version 7.6.3, stage 2 booted by GHC version 7.4.2
Using binary package database: /opt/ghc763/lib/ghc-7.6.3/package.conf.d/package.cache
Using binary package database: /home/feuerbach/.ghc/i386-linux-7.6.3/package.conf.d/package.cache
Make sure that the database which has persistent is listed there.
Hopefully helpful to someone. Using ghci -v I looked to see if persistent was there, and saw this:
package persistent-2.0.8-cec952b1a61645f47dbec3b0b0cbcef4 is unusable due to missing or recursive dependencies: aeson-0.8.0.0-1bd8b5254a1dd30c0fe6acc346ad7de7 attoparsec-0.12.1.2-48393fcdbcf426085b696dc4409d9270 conduit-1.2.0.2-39f9cd0430ed7b7f4306899cbeb1ed83 monad-logger-0.3.7.2-3e6a80e9b3adf31497ff04514bdf2919 resource-pool-0.2.3.0-c02186641e7173f72887d5e65a646ac1 scientific-0.3.3.1-13e0eefbd7215e4503420c3d0a6fdb82 unordered-containers-0.2.5.0-147c3bb8f4a2da7d753455e75af30b92
So I looked around on SO (saw this: Haskell Cabal: Mysterious missing or recursive dependencies) but didn't find a great answer. I did find a good one here though:
$ ghc-pkg list Cabal
Which revealed I had 2 goddamn cabals! One in user and one in global. Ugh. So I was able to do ghc-pkg unregister --user Cabal-1.18.1.3 --force to get rid of the old one. Then cabal install cabal automatically went for 1.20, implicitly into user without any flag (the alternate would be --global).
The problem only occurs in GHCi, right? Have you restarted GHCi since installing persistent? (Maybe there's another way to get GHCi to pick up newly installed packages, but I'm not aware of it.