I opened a Haskell file on a fresh installation of Emacs & Intero. While booting up, intero is trying to install an isolated GHC. This even though my project has stack.yaml which has system-ghc: true. Running stack install in this directory does not reinstall GHC.
Is there any way to make Intero use system ghc instead of reinstalling?
The emacs mode is probably trying to install the intero binary outside the context of your project, to ensure that the intero binary isn't affected by the project's library choices. I'm guessing that setting system-ghc: true in your user config file (~/.stack/config.yaml) instead will solve this problem.
You may also want to set install-ghc: false to disable automatic GHC installation.
Related
I am using Intero under emacs to edit my new Haskell project. I added an import to a third-party library to my code to see if Intero would automatically add the necessary dependency, but it didn't. So I edited the .cabal file manually to add the necessary dependency. Now what do I do - short of restarting emacs?
I've tried running cabal install --dependencies-only; cabal configure at the command line and they ran successfully, but the flycheck buffer still shows an error.
All that is necessary is to run
M-x intero-restart
in emacs.
Intero uses stack which has its own private sandbox for each package you are developing, so cabal install --dependencies-only isn't needed or useful.
I am using stack for my Haskell development and Syntastic for my error checking when editing in Vim. I have not installed the haskell-platform, instead, I use a stack build --install-ghc to get my environment up and running using the supported GHC, cabal and lts packages.
Normally, I use a cabal sandbox and syntastic works well with this. I see when I do a let g:syntastic_debug=3 in Vim, syntastic runs a cabal configure which checks if the project dependencies are installed and then goes ahead and does some hlint, hdevtools and ghc-mod magic to give me some warnings and/or error messages.
Now, here is my problem. Since my cabal setup (installed from stack) doesn't know about my dependencies installed at .stack-work or .stack (not sure), it complains that I am missing necessary packages and blows up when syntastic runs in my Vim instance.
Trying to run a stack exec -- cabal configure returns the following error:
Use of GHC's environment variable GHC_PACKAGE_PATH is incompatible with Cabal. use the flag --package-db to specify a package database (it can be used multiple times).
I haven't found out how to pass the --package-db option with the correct database. Nothing seems to work there.
So, the quetion - will successfully running a stack exec -- cabal configure, avoiding the GHC_PACKAGE_PATH issue get me to a working setup? Can anyone give me some direction here?
hdevtools works. See here: http://seanhess.github.io/2015/08/05/practical-haskell-editors.html
I'm planning on keeping that up to date as new tools come out (like stack-ide).
This blogpost gives a nice introduction as well. Things change quickly in the haskell world and ghc-mod seems to be working well with stack now. The setup from the post requires neovim though.
The setup from the post worked perfectly fine for me and found all dependencies within the current stack project.
There are several things I'm confused about here, so I'll try to explain each of them as clearly as I can.
I've been trying to install the diagrams package for haskell, using cabal. I've seen it suggested to install packages using sandboxes, so that's what I did. Something that's not clear to me is exactly what a sandbox is - I understand that I can initialise one with cabal sandbox init and install packages inside of it with cabal install, but I don't see how to use those packages once they're installed.
I then tried to compile a test-script using ghc, which resulted in the following error:
diagramstutorial.lhs:3:10:
Could not find module 'Diagrams.Prelude'
Use -v to see a list of the files searched for.
With a similar error for another module that the script was supposed to load. These modules are definitely both included in the diagrams package, and cabal seems happy that the package is installed correctly. I expect there's something simple I just don't understand, but I don't know what it is.
I typed ghc --make diagramstutorial.lhs to compile it
That will make GHC use the regular user package database (that is, not the sandbox one). Use cabal exec -- ghc --make diagramstutorial.lhs instead, so that GHC runs in the context of your sandbox.
You can also use GHCi within the sandbox with cabal repl. And naturally, if/when you start preparing a cabal package, all cabal commands (cabal build, etc.) will use the sandbox if you are within its directory.
Something that's not clear to me is exactly what a sandbox is
A set of packages with an accompanying database local to the directory. Beyond the cabal.sandbox.config configuration file there is also a hidden directory .cabal-sandbox, in which diagrams and the other packages you installed lie.
Find the sandbox directory, and locate the packages.conf.d file.
For example, /home/user/.cabal-sandbox/x86_64-linux-ghc-7.8.4-packages.conf.d
Rerun your GHC commands with the package-db flag:
ghci -package-db /home/user/.cabal-sandbox/x86_64-linux-ghc-7.8.4-packages.conf.d --make diagramstutorial.lhs
Everything should now work
I'm going to install GHC on a fresh copy of Ubuntu and I'm wondering: How can I ensure that profiling libraries are installed for the core libraries (e.g., text, unordered-containers)?
I'm aware of the changing the profiling option in cabal's .config file but my understanding is that this only ensures that profiling libraries are installed for those packages that I install AFTER setting up cabal (see italicized text in update below).
(I inadvertently blew up my Ubuntu vbox last night as a result of trying to retroactively install profiling libraries for installed GHC packages. It led to the existing packages not working, which led to me trying to uninstall GHC, which led to...KABOOM!)
UPDATE:
I've installed GHC and am now at the point where I'm about to install cabal. I've confirmed my suspicion that I'm facing a "chicken-and-an-egg" dilemma: In order to get the initial cabal config file (in which I can set profiling option as True), I need to install cabal. However, installing cabal results in the installation of core packages (e.g., text, unordered-containers) BEFORE I get a chance to make the change in the cabal config file.
SOLVED:
As per Daniel Wagner's suggestion (thanks!), I made a couple of modifications to the bootstrap.sh script file (I unfortunately didn't have my old cabal or I would've followed his other suggestion). As reference for future readers, the beginning of my bootstrap.sh file looked like this (after the changes):
#VERBOSE
DEFAULT_CONFIGURE_OPTS="--enable-library-profiling --enable-shared"
EXTRA_CONFIGURE_OPTS=${EXTRA_CONFIGURE_OPTS-$DEFAULT_CONFIGURE_OPTS}
#EXTRA_CONFIGURE_OPTS
#EXTRA_BUILD_OPTS
#EXTRA_INSTALL_OPTS
The preferred solution is to install cabal-install via your package manager. If you have an old version of cabal-install in your package manager, you can then use the old version to install the new version with a config in place, or even specify profiling directly on the command line via cabal install cabal-install --enable-library-profiling.
An alternate solution if you plan to install cabal-install via its bootstrap.sh script is to use the environment variables it provides for configuration. There are four, notated at the top of bootstrap.sh; the relevant one is EXTRA_CONFIGURE_OPTS, which contents get passed to the configure step of each package's Setup command. So something like this ought to do the trick (though I haven't tested it):
EXTRA_CONFIGURE_OPTS=--enable-library-profiling ./bootstrap.sh
I'm experimenting a problem with the interaction between the ghc-mod plugin in emacs, and NixOS 14.04. Basically, once packages are installed via nix-env -i, they are visible from ghc and ghci, recognised by haskell-mode, but not found by ghc-mod.
To avoid information duplication, you can find all details, and the exact replication of the problem in a VM, in the bug ticket https://github.com/kazu-yamamoto/ghc-mod/issues/269
The current, default, package management set up for Haskell on NixOS does work will with packages that use the ghc-api, or similar (ghc-mod, hint, plugins, hell, ...) run time resources. It takes a little more work to create a Nix expression that integrates them well into the rest of the environment. It is called making a wrapper expression for the package, for an example look at how GHC is installed an operates on NixOS.
It is reasonable that this is difficult since you are trying to make a install procedure that is atomic, but interacts with an unknown number of other system packages with their own atomic installs and updates. It is doable, but there is a quicker work around.
Look at this example on the install page on the wiki. Instead of trying to create a ghc-mod package that works atomically you weld it on to ghc so ghc+ghc-mod is an atomic update.
I installed ghc+ghc-mod with the below install script added to my ~/.nixpkgs/nixpkgs.nix file.
hsEnv = haskellPackages.ghcWithPackages (self : [
self.ghc
self.ghcMod
# add more packages here
]);
Install package with something like:
nix-env -i hsEnv
or better most of the time:
nix-env -iA nixpkgs.haskellPackages.hsEnv
I have an alias for the above so I do not have to type it out every time. It is just:
nixh hsEnv
The down side of this method is that other Haskell packages installed with nix-env -i[A] will not work with the above installation. If I wanted to get everything working with the lens package then I would have to alter the install script to include lens like:
hsEnv = haskellPackages.ghcWithPackages (self : [
self.ghc
self.ghcMod
self.lens
# add more packages here
]);
and re-install. Nix does not seem to use a different installation for lens or ghc-mod in hsEnv and with the ghc from nix-env -i ghc so apparently only a little more needs to happen behind the scenes most of the time to combine existing packages in the above fashion.
ghc-mod installed fine with the above script but I have not tested out its integration with Emacs as of yet.
Additional notes added to the github thread
DanielG:
I'm having a bit of trouble working with this environment, I can't even get cabal install to behave properly :/ I'm just getting lots of errors like:
With Nix and NixOS you pretty much never use Cabal to install at the global level
Make sure to use sandboxes, if you are going to use cabal-install. You probably do not need it but its there and it works.
Use ghcWithPackages when installing packages like ghc-mod, hint, or anything needs heavy runtime awareness of existing package (They are hard to make atomic and ghcWithPackages gets around this for GHC).
If you are developing install the standard suite of posix tools with nix-env -i stdenv. NixOS does not force you to have your command line and PATH cultured with tools you do not necessarily need.
cabal assumes the existence a few standard tools such as ar, patch(I think), and a few others as well if memory services me right.
If you use the standard install method and/or ghcWithPackages when needed then NixOS will dedup, on a package level (If you plot a dependency tree they will point to the same package in /nix/store, nix-store --optimise can always dedup the store at a file level.), many packages automatically unlike cabal sandboxes.
Response to comment
[carlo#nixos:~]$ nix-env -iA nixos.pkgs.hsEnv
installing `haskell-env-ghc-7.6.3'
these derivations will be built:
/nix/store/39dn9h2gnp1pyv2zwwcq3bvck2ydyg28-haskell-env-ghc-7.6.3.drv
building path(s) `/nix/store/minf4s4libap8i02yhci83b54fvi1l2r-haskell-env-ghc-7.6.3'
building /nix/store/minf4s4libap8i02yhci83b54fvi1l2r-haskell-env-ghc-7.6.3
collision between `/nix/store/1jp3vsjcl8ydiy92lzyjclwr943vh5lx-ghc-7.6.3/bin/haddock' and `/nix/store/2dfv2pd0i5kcbbc3hb0ywdbik925c8p9-haskell-haddock-ghc7.6.3-2.13.2/bin/haddock' at /nix/store/9z6d76pz8rr7gci2n3igh5dqi7ac5xqj-builder.pl line 72.
builder for `/nix/store/39dn9h2gnp1pyv2zwwcq3bvck2ydyg28-haskell-env-ghc-7.6.3.drv' failed with exit code 2
error: build of `/nix/store/39dn9h2gnp1pyv2zwwcq3bvck2ydyg28-haskell-env-ghc-7.6.3.drv' failed
It is the line that starts with collision that tells you what is going wrong:
collision between `/nix/store/1jp3vsjcl8ydiy92lzyjclwr943vh5lx-ghc-7.6.3/bin/haddock' and `/nix/store/2dfv2pd0i5kcbbc3hb0ywdbik925c8p9-haskell-haddock-ghc7.6.3-2.13.2/bin/haddock' at /nix/store/9z6d76pz8rr7gci2n3igh5dqi7ac5xqj-builder.pl line 72.
It is a conflict between two different haddocks. Switch to a new profile and try again. Since this is a welding together ghc+packages it should not be installed in a profile with other Haskell packages. That does not stop you from running binaries and interrupters from both packages at once, they just need to be in their own name space so when you call haddock, cabal, ghc, there is only one choice per profile.
If you are not familiar with profiles yet you can use:
nix-env -S /nix/var/nix/profiles/per-user/<user>/<New profile name>
The default profile is either default or channels do not which one it will be for your set up. But check for it so you can switch back to it later. There are some tricks so that you do not have to use the /nix/var/nix/profiles/ directory to store you profiles to cut down on typing but that is the default location.