(Deprecated) Please use stack !
hsenv is a tool (inspired by Python's virtualenv) to create isolated Haskell environments. This is the clone of tmhedberg/hsenv written in shellscript.
It creates a sandboxed environment in a .hsenv/ subdirectory of your project, which, when activated, allows you to use regular Haskell tools (ghc, ghci, ghc-pkg, cabal) to manage your Haskell code and environment. It's possible to create an environment, that uses a different GHC version than your currently installed system GHC version. Very simple emacs integration mode is included.
-
Check out hsenv.sh into
~/.hsenv.git clone https://github.com/saturday06/hsenv.sh.git ~/.hsenv -
Add
~/.hsenv/binto your$PATHfor access to thehsenvcommand-line utility.export PATH="$HOME/.hsenv/bin:$PATH"
First, choose a directory where you want to keep your sandboxed Haskell environment, usually a good choice is a directory containing your cabalized project (if you want to work on a few projects (perhaps an app and its dependent library), just choose any of them, it doesn't really matter). Enter that directory:
cd ~/projects/fooNext, create your new isolated Haskell environment (this is a one-time-only (per environment) step):
hsenvNow, every time you want to use this environment, you have to activate it:
source .hsenv/bin/activateThat's it! Now it's possible to use all regular Haskell tools like usual, but it won't affect your global/system Haskell environment, and also your per-user environment (from ~/.cabal and ~/.ghc) will stay the same. All cabal-installed packages will be private to this environment, and the external environments (global and user) will not affect it (this environment will only inherit very basic packages, mostly ghc and Cabal and their deps).
When you're done working with this environment, enter command deactivate_hsenv,
or just close the current shell (with exit).
deactivate_hsenvBy default, hsenv creates an "unnamed" environment, but sometimes for
particular use cases you might want to create different environments under
the same directory. This is achievable creating a "named" environment. To
do that, just pass the flag --name=<ENVIRONMENT_NAME> to hsenv:
hsenv --name=<ENVIRONMENT_NAME>This will make hsenv generate a folder of the form .hsenv_<ENVIRONMENT_NAME>.
If you want to customize activation and deactivation, create one or more of the following files in ~/.hsenv/bin/: pre-activate, post-activate, pre-deactivate, post-deactivate. These shell scripts will be sourced automatically by the main activation script.
Here's the most advanced usage of hsenv. Let's say you want to:
- Hack on a json library
- Do so comfortably
- Use your own version of the parsec library
- And do all this using the nightly version of GHC
First, download the binary distribution of GHC for your platform (e.g. ghc-7.3.20111105-i386-unknown-linux.tar.bz2).
Create a directory for you environment:
mkdir /tmp/test
cd /tmp/testThen, create a new environment using that GHC:
hsenv --name=test --ghc=/path/to/ghc-7.3.20111105-i386-unknown-linux.tar.bz2Activate it:
source .hsenv_test/bin/activateDownload a copy of json library and your private version of parsec:
darcs get http://patch-tag.com/r/Paczesiowa/parsec
cabal unpack jsonInstall parsec:
cd parsec2
cabal installInstall the rest of the json deps:
cd ../json-0.5
cabal install --only-dependenciesNow, let's say you want to hack on Parsec module of json library. Open it in emacs:
emacsclient Text/JSON/Parsec.hsActivate the virtual environment (hsenv must be required earlier):
M-x hsenv-activate <RET> /tmp/test/ <RET>
Edit some code and load it in ghci using 'C-c C-l'. If it type checks, you can play around with the code using nightly version of ghci running in your virtual environment. When you're happy with the code, exit emacs and install your edited json library:
cabal installAnd that's it.
Recent versions of hsenv include the possibility to automatically download and install a GHC version directly from the GHC main repository. To do that, all you need to do is to pass the desired version of GHC you want to install:
hsenv --ghc=7.4.1Or a valid URL pointing to a compressed GHC archive:
hsenv --ghc=http://www.haskell.org/ghc/dist/7.6.3/ghc-7.6.3-x86_64-apple-darwin.tar.bz2hsenv has been tested on Linux, Mac OS X, FreeBSD, and MSYS(1&2) systems, but it should work on any POSIX platform. The external (from tarball) GHC feature requires a binary GHC distribution compiled for your platform which that can be extracted with tar and installed with "./configure --prefix=PATH; make install".
Q: Can I use it together with tools like cabal-dev or capri?
A: No. All these tools work more or less the same (wrapping cabal command, setting GHC_PACKAGE_PATH env variable), so something will probably break.
Q: Using GHC from tarball fails with a bunch of make tool gibberish on FreeBSD. What do I do?
A: Try the '--make-cmd=gmake' switch.
Q: Can I use hsenv inside hsenv?
A: No. It may be supported in future versions.
Q: Does it work on x64 systems?
A: Yes.
Q: Will it work on Mac?
A: Yes.
Q: Will it work on Windows?
A: Yes. It has been tested on MSYS and MSYS2.
Q: Does it require Bash?
A: No, it should work with any POSIX-compliant shell. It's been tested with bash, bash --posix, dash, zsh and ksh.
Q: Can I use it with a different haskell package repository than hackage?
A: Yes, just adjust the url in .hsenv/cabal/config file.
Q: How do I remove the whole virtual environment?
A: If it's activated - 'deactivate_hsenv' it. Then, delete the .hsenv/ directory.
Q: Is every environment completely separate from other environments and the system environment?
A: Yes. The only (minor) exception is ghci history - there's only one per user history file. Also, if you alter your system's GHC, then virtual environments using system's GHC copy will probably break. Virtual environments using GHC from a tarball should continue to work.
Q: Can I share one cabalized project directory among multiple environments (e.g. build a cabalized project in the same directory using different environments)?
A: Yes. hsenv also overrides cabal with a wrapper, that will force using different build directories, so there shouldn't be even any recompilation between different environments.
Q: Is it possible to activate/deactivate an environment upon entering/leaving its directory?
A: Yes, if you really know what you're doing. Here's a snippet for bash, which will activate both named and unnamed environments:
precmd() {
local search_dir=$PWD
while [ $search_dir != "/" ]; do
local hsenv_found=false
for dir in `cd $search_dir && find . -maxdepth 1 -type d -name ".hsenv*"`; do
if $hsenv_found; then
echo multiple environments in $search_dir , manual activaton required
return
elif [ -n "$dir" ] && [ -e $search_dir/$dir/bin/activate ]; then
hsenv_found=true
fi
done
if ! $hsenv_found; then
search_dir=`cd $search_dir/.. && pwd`
continue
fi
if [ -n "$HSENV" ] && [ "$HSENV" != "$search_dir" ]; then
deactivate_hsenv
fi
if [ -z "$HSENV" ]; then
pwd_backup=$PWD
cd $search_dir
source .hsenv*/bin/activate
cd $pwd_backup
fi
return
done
if [ -n "$HSENV" ]; then
deactivate_hsenv
fi
}
export PROMPT_COMMAND=precmd
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