Whenever I try to load the vector package in ghci I get the following:
Prelude> :set -package vector
cannot satisfy -package vector:
vector-0.12.0.1-6mmeV84KOvJADXavl6mOiY is unusable due to shadowed dependencies:
primitive-0.6.2.0
(use -v for more information)
vector is installed in my cabal sandbox and I'm running cabal repl to get to ghci. Is importing vector simply not possible or is there a way around it? I'm on OSX.
I'm not sure what is causing that error message in your case, but one possibility is to use Stack's ghci command like so:
stack ghci --package vector
You can get Stack by following the instructions at https://haskell-lang.org/get-started, or since you're on OS X by running:
curl -sSL https://get.haskellstack.org/ | sh
There was an issue with full 8.2.1 binary platform builds that's just been resolved: https://mail.haskell.org/pipermail/haskell-cafe/2017-October/127979.html
This was likely an instance of that.
Related
vector module has been installed by "cabal install vector"
bash-3.2$ ghc-pkg list -f $HOME/.cabal/store/ghc-9.2.1/package.db
/Users/gcolpitts/.cabal/store/ghc-9.2.1/package.db
primitive-0.7.3.0
vector-0.12.3.1
but the compiler can't find it:
$ ghc prob214ff.hs
[1 of 1] Compiling Main ( prob214ff.hs, prob214ff.o )
prob214ff.hs:14:1: error:
Could not find module ‘Data.Vector’
Perhaps you meant Data.Functor (from base-4.16.0.0)
Use -v (or `:set -v` in ghci) to see a list of the files searched for.
|
14 | import Data.Vector
Thx #n. 1.8e9-where's-my-share !
ghc -package-db $HOME/.cabal/store/ghc-9.2.1/package.db prob214ff.hs
solves my problem although it is a regression from previous versions of ghc which didn't require the use of the -package-db option.
I'd love to use GHC_PACKAGE_PATH but I can't see how to make that work. Sec 5.9.5 of the ghc users guide is confusing. It states "A package database is where the details about installed packages are stored. It is a directory, usually called package.conf.d." i.e. not the package.db file that I gave with -package-db on the command line. But where is the package.conf.db directory with info on the vector package that I installed with cabal?
"ghc-pkg list" references /usr/local/lib/ghc-9.2.1/lib/package.conf.d but the output of the command doesn't list the vector package I installed.
"ghc-pkg list -f $HOME/.cabal/store/ghc-9.2.1/package.db" does list the vector package in it's output but doesn't tell me a package.conf.d directory that knows about the vector package.
This is a bit fiddly with cabal version 2. Installing packages no longer really makes sense (despite the cabal install still existing...). Instead you will probably find it easiest to create a cabal package instead, for example:
$ mkdir my-package
$ cd my-package
$ cabal init
<Edit my-package.cabal and add vector to the build-depends line>
<Put the contents of prob214ff.hs in app/Main.hs instead>
$ cabal run
This will be fixed in 9.2.2, see https://gitlab.haskell.org/ghc/ghc/-/issues/20660#note_391573
I install GHC on Windows10 using the recommended Haskell Stack. I want to us GHC without all the Stack overhead for Advent of Code. This was working fine until I tried to get the extra package.
I can install it with Stack, but I don't seem to have a way to get it in the global package database. Haskell Stack apparently does not install the cabal executable and seems to have it locked out of their package database.
How do I install the extra package for use with vanilla GHC?
John Miller#DESKTOP-NENAGQH MSYS /d/dev/AdventOfCode2020
$ stack ghc -- AoC/Utils.hs
[1 of 1] Compiling AoC.Utils ( AoC\Utils.hs, AoC\Utils.o )
John Miller#DESKTOP-NENAGQH MSYS /d/dev/AdventOfCode2020
$ ghc AoC/Utils.hs
[1 of 1] Compiling AoC.Utils ( AoC\Utils.hs, AoC\Utils.o ) [Data.List.Extra changed]
AoC\Utils.hs:3:1: error:
Could not find module `Data.List.Extra'
Use -v (or `:set -v` in ghci) to see a list of the files searched for.
|
3 | import Data.List.Extra
| ^^^^^^^^^^^^^^^^^^^^^^
I don't know whether stack supports installing to the global package DB. cabal does though:
$ cabal install --lib extra
Resolving dependencies...
Up to date
$ ghci
GHCi, version 8.10.2: https://www.haskell.org/ghc/ :? for help
Loaded package environment from /home/simon/.ghc/x86_64-linux-8.10.2/environments/default
Prelude> import Data.List.Extra
Prelude Data.List.Extra>
Ok, so stack can install the cabal executable if you beat at it long enough. The package is called cabal-install and it is not in any resolver, but is on Hackage.
stack install cabal-install
Because it is not in the resolver there is a pretty good chance that the version of Cabal, the library for manipulating cabal packages in Haskell, is not compatible. First, ask stack where it keeps its global config
stack path --config-location
Edit that file to allow for the needed dependencies under extra-deps: Stack will helpfully tell you what they are. It may also be helpful to change the resolver to a newer version in that file while your at it.
Now try
stack install cabal-install
again and if these instructions have not fallen out of date since December 2020 you will get the cabal executable somewhere potentially useful.
Before using cabal you will have to run a cabal update to get the package list.
At this point cabal should manipulate your global package database and stack can install GCH and all its libraries over and over and over again if you want to use it for a project instead. They should just keep out of each other's way.
I was trying acid example but compile error.
The error message says no instance No instance for MonadState, No instance for MonadReader.
This article says it is due to two different mtl versions installed.
And I am using nix-shell in nixos:
ghc-pkg list | grep acid
acid-state-0.14.3
ghc-pkg list | grep mtl
mtl-2.2.1
mtl-2.2.2
However, if I don't use acid-state package when I enter nix-shell, I got:
ghc-pkg list | grep mtl
mtl-2.2.2
That probably means acid-state is using different mtl version than Control.Monad.Reader.
But acid-state's stack.yaml in github is lts-11.15, which has mtl-2.2.2.
So what should I do to make it work?
Stack and Cabal-install have similar problems when dealing with GHC's package dbs, but these problems can be avoided:
Stack
When I use Stack, I don't run it in a nix-shell, so that the nix-shell can't add packages to the wrapped GHC command that Stack will then consider to be system packages ('global' in Cabal terminology). I am not sure whether this is the only valid approach though.
Cabal-install only
When calling Cabal in a nix-shell, you should add these flags to prevent GHC from looking at the wrong package db: cabal configure --package-db=clear --package-db=global. The GHC wrapper will make the Nix-managed dependencies appear in the 'global' package db.
A minimal reproduction can be found here:
https://github.com/IvanMalison/stack-gtk2hs-bug
Everything works as expected when I use normal stack commands, but when I run the failing command:
stack ghc -- --make main.hs
I get the following error:
main.hs:3:1: error:
Ambiguous interface for ‘Graphics.UI.Gtk’:
it was found in multiple packages: gtk-0.14.6 gtk3-0.14.6
main.hs:4:1: error:
Ambiguous interface for ‘Graphics.UI.Gtk.Abstract.Widget’:
it was found in multiple packages: gtk-0.14.6 gtk3-0.14.6
main.hs:5:1: error:
Ambiguous interface for ‘Graphics.UI.Gtk.Layout.Table’:
it was found in multiple packages: gtk-0.14.6 gtk3-0.14.6
The output of stack exec ghc-pkg -- --no-user-package-db list is https://gist.github.com/f19f900988f49e4d03cd61f1cab48baa . This output makes me expect that the reason that this is happening is that some other stack install required gtk (not gtk3 which is what is specified as a dependency in this package) and somehow this package is visible from the stack ghc command for some reason.
Am I misunderstanding the stack ghc command? Shouldn't this essentially do the same thing as stack build?
There's no builtin way to do this with stack currently. However, it is possible to get stack ghci to do this. The most straightforward way to do it is to make a cabal package which has the executable target. However, if you really want to just use straight ghc, there is a way. Copy-pasting from my comment here:
stack ghc works a bit differently than stack ghci. It's essentially a synonym for stack exec -- ghc, which will run the right compiler with the right databases, but won't set up anything related to your local packages like include directories etc. Note that stack ghci takes TARGET arguments whereas stack ghc does not. Retrospectively, this is a bit inconsistent, but stack ghc came before stack ghci.
It does make sense to have the ability to do something like this, though not sure how to best achieve that. Some potential options:
--no-interactive argument on stack ghci. Would be a bit obtuse. Weird to run a ghci command when, though it would be using the stack ghci logic.
Add --target TARGET option to stack ghc, to tell it to use the environment of a particular local package target.
Here's a workaround for now. Put the following in ~/.local/bin/stack-run-ghc.sh and make it user executable:
#/bin/sh
ghc $(echo "$*" | sed 's/--interactive//g')
This takes the arguments, removes --interactive, and calls ghc. With this, I can build stack using ghc via the following:
stack ghci --with-ghc stack-run-ghc.sh --ghci-options src/main/Main.hs
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.