I'm starting a new project that will hopefully use gtk2hs. However, I can not get this package to install on my fairly typical Linux box. Here is the failure :
[1 of 2] Compiling SetupWrapper ( /tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs, /tmp/cairo-0.12.4-4201/cairo-0.12.4/dist/dist-sandbox-58b5f9c6/setup/SetupWrapper.o )
/tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs:94:45:
Ambiguous occurrence `moreRecentFile'
It could refer to either `SetupWrapper.moreRecentFile',
defined at /tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs:149:1
or `Distribution.Simple.Utils.moreRecentFile',
imported from `Distribution.Simple.Utils' at /tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs:8:1-32
/tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs:95:45:
Ambiguous occurrence `moreRecentFile'
It could refer to either `SetupWrapper.moreRecentFile',
defined at /tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs:149:1
or `Distribution.Simple.Utils.moreRecentFile',
imported from `Distribution.Simple.Utils' at /tmp/cairo-0.12.4-4201/cairo-0.12.4/SetupWrapper.hs:8:1-32
Failed to install cairo-0.12.4
[1 of 2] Compiling SetupWrapper ( /tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs, /tmp/glib-0.12.4-4201/glib-0.12.4/dist/dist-sandbox-58b5f9c6/setup/SetupWrapper.o )
/tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs:94:45:
Ambiguous occurrence `moreRecentFile'
It could refer to either `SetupWrapper.moreRecentFile',
defined at /tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs:149:1
or `Distribution.Simple.Utils.moreRecentFile',
imported from `Distribution.Simple.Utils' at /tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs:8:1-32
/tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs:95:45:
Ambiguous occurrence `moreRecentFile'
It could refer to either `SetupWrapper.moreRecentFile',
defined at /tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs:149:1
or `Distribution.Simple.Utils.moreRecentFile',
imported from `Distribution.Simple.Utils' at /tmp/glib-0.12.4-4201/glib-0.12.4/SetupWrapper.hs:8:1-32
Failed to install glib-0.12.4
It seems to be related to recent cabal versions, since that used to work before. It seems to be a known bug (http://trac.haskell.org/gtk2hs/ticket/1292 , http://trac.haskell.org/gtk2hs/ticket/1291 and http://trac.haskell.org/gtk2hs/ticket/1289), however it has not moved for weeks. I am not sufficiently competent to suggest a good fix, so I would like your advice. This is very annoying since I am stuck on this important project, and it pains me to think that the main GUI lib of our language has been broken for many weeks now.
cabal-install version 1.18.0.2 using version 1.18.1.1 of the Cabal library / ghc 7.4.1
Thanks for your help
The correct solution for now is to build from darcs. Detailed instructions are given in the Getting the latest and greatest section of the installation instructions; the short version is:
darcs get --lazy http://code.haskell.org/gtk2hs
cd gtk2hs
sh bootstrap.sh
EDIT: The official 0.12.5 release of gtk2hs from December 2013 supports cabal 1.18, so the above darcs instructions are no longer needed. The full installation instructions are still available from the Gtk2Hs download page; the short version is:
cabal install gtk2hs-buildtools
cabal install gtk gtk3
You can try with older Cabal version using cabal install --cabal-lib-version=1.16.0 gtk.
Related
I wanted to get going with Haskell a little bit and therefore took a look at the Spock framework. To start clean, I uninstalled everything Haskell related from my Arch Linux machine and installed ghcup, Cabal and Stack using the install scripts from their respective websites.
Now I want to follow Spock's Tutorial. Trying to install Spock globally with cabal install Spock as suggested gives me an error (abbreviated):
src/Web/Spock/Internal/Wire.hs:43:1: error:
Could not find module ‘Web.Routing.AbstractRouter’
Use -v (or `:set -v` in ghci) to see a list of the files searched for.
|
43 | import Web.Routing.AbstractRouter
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
cabal: Failed to build Spock-0.9.0.1. See the build log above for details.
I already found a question on reddit on the topic, but the solution does not apply because I'm not trying to use a specific version of the libraries as implied.
So I try to follow along and build only locally.
But when I reach the point where it says stack build --fast --pedantic, the build plan can not be constructed and Stack suggests to add another dependency, stm-containers. Doing so, I am presented with two additional suggestions for focus and primitive. When I add these, the plan fails again, this time without a simple solution:
In the dependencies for primitive-0.6.4.0:
base-4.13.0.0 from stack configuration does not match >=4.5 && <4.13 (latest matching version is 4.12.0.0)
needed due to Spock-example-0.1.0.0 -> primitive-0.6.4.0
I can do a little thing with Haskell, but with the build system(s), I am way out of my comfort zone. Help and hints appreciated. Oh, and all versions of course are the latest by the time of this post.
Due to incompatible versions of dependencies, Spock won't build with GHC 8.8 and above. A similar problem is described in Spock issue #149, though I'm not fully sure it is exactly the same incompatibility. The error you got from Stack hints at that, as base-4.13.0.0 is the version of base that is bundled with GHC 8.8. cabal-install failed in a more obscure way because, upon noting the incompatibility, it tries to solve the dependencies using older versions of Spock, eventually picking 0.9.0.1, attempting and, thanks to a missing version upper bound for the reroute dependency, failing to build it.
(Shortly after this answer was posted, the missing upper bound was retrofitted to the old Spock version, so attempting to reproduce the problem now will lead to an easier to understand failure.)
Casting the tutorial aside, the most straightforward way to use Spock given those complications is probably through cabal-install 3+. Begin by using ghcup to switch to GHC 8.6.5:
$ ghcup install 8.6.5
$ ghcup set 8.6.5
Then, create a blank project with cabal-install:
$ mkdir myproject
$ cd myproject
$ cabal init
Add Spock to the build-depends section of myproject.cabal:
build-depends: base >=4.12 && <4.13
, Spock == 0.13.*
Finally, you can run:
$ cabal build
Which will install Spock and its dependencies before building the project. (Note that you generally don't need to use cabal install to install libraries with cabal-install 3.)
It is presumably possible to make it work with Stack as well, by changing to the lts-14.27 resolver (the latest one that uses GHC 8.6.5), tracking down all dependency versions that need to be overriden (as you had began to do) and manually adding them to the extra-deps of stack.yaml.
I am attempting to install the code for "Haskell: The Craft of Functional Programming", 3rd edition.
I'm using GHCi, version 7.6.3 on Centos version 7.
Then:
cabal unpack Craft3e
cd Craft3e-0.1.1.0/
cabal install
...
[29 of 67] Compiling CalcParseLib ( Calculator/CalcParseLib.hs, dist/build/CalcParseLib.o )
Calculator/CalcParseLib.hs:132:10:
Not in scope: type constructor or class `Applicative'
Failed to install Craft3e-0.1.1.0
cabal: Error: some packages failed to install:
Craft3e-0.1.1.0 failed during the building phase. The exception was:
ExitFailure 1
I have attempted this installation multiple times, but cannot
overcome this error.
Could I use something other than "cabal install"?
I have plenty to learn about Haskell before I get to this example,
but it would be great to know the installation is fine! :)
You have three options:
Install an older version of the Craft3e package, with e.g. cabal unpack Craft3e-0.1.0.10.
Find Calculator/CalcParseLib.hs in the source files you have downloaded with cabal unpack and add a...
import Control.Applicative
... line next to the other import lines at the beginning. I suspect you will have to do the same with other modules, if the same error shows up elsewhere after you do this change, and there might be other issues of a similar nature.
Install a newer version of GHC (7.6.3 is from 2013). Though the default CentOS repositories won't offer that, there are other options, such as an unofficial Fedora repository and a manual installation. See this page for instructions.
#3 is the definitive solution. If you just want to get started with the book right now, though, you can go for #1 and leave the reinstall for later.
For the sake of reference, here is a brief explanation of the problem (I will use some unfamiliar terms, but you will soon enough learn about them as you study Haskell). There is an important type class called Applicative which, for historical reasons, wasn't as well integrated with the rest of the core libraries as it should be. This situation was corrected in GHC 7.10, which both included Applicative in the Prelude (the module which is imported by default in Haskell programs) and made it necessary to add Applicative instances in a number of places where they were missing. The code in the Craft3e package was updated so that these Applicative instances were in place (cf. this entry in the book's blog), but the import Control.Applicative line, which would be necessary to make the updated code work in older GHCs that do not have Applicative in the Prelude, wasn't added, leading to the error that you are seeing.
I have some familiarity with Haskell, the language, but not so much with the toolchain. (I played around with Haskell before cabal and stack existed.) I'm told that stack is the tool I should be using to manage Haskell projects. I'm trying to learn the haste library, and I'm getting stymied on the first tutorial I've tried, because I can't get hplayground installed. I created a stack project; my stack.yaml has
extra-deps:
- ghc-simple-0.3
- haste-compiler-0.5.3
- shellmate-0.2.3
- haste-perch-0.1.0.9
- hplayground-0.1.3.1
and my .cabal file has hplayground listed in the build-depends. But when I run stack build, I get these errors:
Configuring haste-perch-0.1.0.9...
Building haste-perch-0.1.0.9...
Preprocessing library haste-perch-0.1.0.9...
Haste/Perch.hs:17:15: Warning:
-XOverlappingInstances is deprecated: instead use per-instance pragmas OVERLAPPING/OVERLAPPABLE/OVERLAPS
Haste/App/Perch.hs:18:15: Warning:
-XOverlappingInstances is deprecated: instead use per-instance pragmas OVERLAPPING/OVERLAPPABLE/OVERLAPS
[1 of 2] Compiling Haste.App.Perch ( Haste/App/Perch.hs, .stack-work/dist/x86_64-osx/Cabal-1.22.4.0/build/Haste/App/Perch.o )
Haste/App/Perch.hs:61:15: Not in scope: ‘newTextElem’
Haste/App/Perch.hs:71:9:
Not in scope: ‘setAttr’
Perhaps you meant ‘jsSetAttr’ (imported from Haste.App)
Haste/App/Perch.hs:76:15:
Not in scope: ‘newElem’
Perhaps you meant one of these:
‘nelem’ (line 75), ‘notElem’ (imported from Prelude)
and a whole lot of similar errors. Any thoughts on what I'm doing wrong?
More broadly: what is a fast, easy way to get up and running with haste for someone who's not experienced with the Haskell toolchain?
Haste's event APIs got overhauled between the 0.4 and 0.5 series, and HPlayground is still on 0.4. If you want to use it, you will unfortunately have to fall back to 0.4 until HPlayground gets patched for 0.5.
For getting started in general, you should install the pre-build binaries if you're on a non-Linux platform (and probably if you're on a Linux platform as well, since you get man-pages and other niceties); the build process can be tricky and is prone to errors.
Once you've done that, you can refer to the docs and resources page on haste-lang.org, which contains links to API docs, video tutorials, source code examples and more.
Once you have installed ghc and cabal installed you will need to install the haste compiler as follows ( from http://haste-lang.org/downloads/ ):
$ cabal update
$ cabal install haste-compiler
$ haste-boot
After doing this, "hastec" ( the haste compiler ) should be available to use to compile haskell to javascript. In addition, "haste-cabal" ( the haste version of cabal ) should be available to use to install libraries such as haste-perch for use in your programs.
The readme file for haste-perch (https://github.com/agocorona/haste-perch) contains the instructions for installing haste-perch. Those instructions use "haste-inst" to install haste-perch but "haste-inst" is obsolete ( and no longer exists ). Use the modified instructions below to install haste-perch:
>git clone http://github.com/agocorona/haste-perch.git
>cd haste-perch
>haste-cabal install
I was able to install haste-perch and successfully build the example that it came with.
I also tried building hplayground but ran into compile problems that looked as if they were due to the code not being updated to use haste 0.5 . For example, "OnClick" was a valid identifier in earlier versions of haste but not anymore:
src/Haste/HPlay/View.hs:820:45:
Not in scope: data constructor ‘OnClick’
Perhaps you meant ‘Click’ (line 1017)
I can't get module "GHC.SrcLoc" in package "srcloc" on Ubuntu Haskell ...
-- "import" works on Windows, but not on Ubuntu 14.04
-- Module name is "GHC.SrcLoc"
-- Cabal build error below
Take 2: tried adding package "srcloc" to Cabal dependencies
^ Adding "srcloc" to dependencies causes "cabal configuration failed". ^
GHCI version...
$ ghci --version
The Glorious Glasgow Haskell Compilation System, version 7.6.3
Please help
https://hackage.haskell.org/package/base-4.8.2.0/docs/GHC-SrcLoc.html
My Haskell Code...
https://github.com/JohnReedLOL/HaskellPrintDebugger
* Attempt #1 *
:~/IdeaProjects/IntelliJHaskellPrintDebugger$ cabal install srcloc
Resolving dependencies...
All the requested packages are already installed:
srcloc-0.5.1.0
Use --reinstall if you want to reinstall anyway.
* Attempt #2 *
-- Tried replacing "import GHC.SrcLoc" with "import Data.Loc", but failed.
-- Tried adding "srcLock" to "build-depends" in .cabal, but failed.
^ Hopeless
Since Data.SrcLoc is a part of the GHC distribution and it wasn't added until (I believe) GHC 7.10.1, it will not exist in GHC 7.6.3. If you install the latest version of GHC, this should work fine.
The package you are seeing that is called srcloc appears to be unrelated to what you want, and does not provide the GHC.SrcLoc module. The GHC.SrcLoc module is instead provided by the GHC base standard library, which is included in (and requires) a newer version of GHC.
Newer versions of GHC also include a lot of other nice features that 7.6.3 (which was released more than 2 years ago) doesn't have.
You also mentioned stack traces, so you might be interested in this.
You must install the srcloc package; in the simple case where you are not using sandboxes, this is done by running cabal install srcloc at the command line.
I first set up Haskell from https://www.haskell.org/platform/ but ghc-mod had problems with sandboxes and to update it I needed a newer cabal which needed a newer ghc. Or something like that. (https://stackoverflow.com/a/28049104/131227 ??)
So I deleted everything, and installed from http://ghcformacosx.github.io/.
Then some strange failure setting up a new sandbox was because something didn't properly have a dependancy for happy. (https://github.com/haskell-suite/haskell-src-exts/issues/14)
Ok. Installed happy. Now trying (again) to install ghc-mod and I get a giant mess (below).
Should I use http://www.stackage.org/?
I've seen some people mention ghc-pkg recache or cabal install cabal-install... Are those things I need to do?
Mess:
Resolving dependencies... Configuring ghc-mod-5.2.1.2... Building ghc-mod-5.2.1.2... Failed to install ghc-mod-5.2.1.2 Build log ( /Users/mark/.cabal/logs/ghc-mod-5.2.1.2.log ): Configuring ghc-mod-5.2.1.2... Building ghc-mod-5.2.1.2... Preprocessing library ghc-mod-5.2.1.2...
Language/Haskell/GhcMod/Convert.hs:1:51: Warning:
-XOverlappingInstances is deprecated: instead use per-instance pragmas OVERLAPPING/OVERLAPPABLE/OVERLAPS [ 1 of 38] Compiling Language.Haskell.GhcMod.Read ( Language/Haskell/GhcMod/Read.hs, dist/build/Language/Haskell/GhcMod/Read.o ) [ 2 of 38] Compiling Language.Haskell.GhcMod.Cabal21 ( Language/Haskell/GhcMod/Cabal21.hs, dist/build/Language/Haskell/GhcMod/Cabal21.o ) [ 3 of 38] Compiling Language.Haskell.GhcMod.Cabal18 ( Language/Haskell/GhcMod/Cabal18.hs, dist/build/Language/Haskell/GhcMod/Cabal18.o ) [ 4 of 38] Compiling Language.Haskell.GhcMod.Cabal16 ( Language/Haskell/GhcMod/Cabal16.hs, dist/build/Language/Haskell/GhcMod/Cabal16.o ) [ 5 of 38] Compiling Language.Haskell.GhcMod.GHCChoice ( Language/Haskell/GhcMod/GHCChoice.hs, dist/build/Language/Haskell/GhcMod/GHCChoice.o ) [ 6 of 38] Compiling Language.Haskell.GhcMod.Error ( Language/Haskell/GhcMod/Error.hs, dist/build/Language/Haskell/GhcMod/Error.o )
Language/Haskell/GhcMod/Error.hs:12:1: Warning:
Module ‘Control.Monad.Error’ is deprecated:
Use Control.Monad.Except instead
Language/Haskell/GhcMod/Error.hs:40:10: Warning:
In the use of type constructor or class ‘Error’
(imported from Control.Monad.Error, but defined in Control.Monad.Trans.Error):
Deprecated: "Use Control.Monad.Trans.Except instead"
Language/Haskell/GhcMod/Error.hs:40:10: Warning:
In the use of type constructor or class ‘Error’
(imported from Control.Monad.Error, but defined in Control.Monad.Trans.Error):
Deprecated: "Use Control.Monad.Trans.Except instead" [ 7 of 38] Compiling Language.Haskell.GhcMod.Utils ( Language/Haskell/GhcMod/Utils.hs, dist/build/Language/Haskell/GhcMod/Utils.o )
Language/Haskell/GhcMod/Utils.hs:15:1: Warning:
The import of ‘Control.Applicative’ is redundant
except perhaps to import instances from ‘Control.Applicative’
To import instances alone, use: import Control.Applicative()
Language/Haskell/GhcMod/Utils.hs:45:51: Warning:
In the use of ‘strMsg’
(imported from Language.Haskell.GhcMod.Error, but defined in Control.Monad.Trans.Error):
Deprecated: "Use Control.Monad.Trans.Except instead" [ 8 of 38] Compiling Language.Haskell.GhcMod.Types ( Language/Haskell/GhcMod/Types.hs, dist/build/Language/Haskell/GhcMod/Types.o ) [ 9 of 38] Compiling Language.Haskell.GhcMod.Gap ( Language/Haskell/GhcMod/Gap.hs, dist/build/Language/Haskell/GhcMod/Gap.o )
Language/Haskell/GhcMod/Gap.hs:256:18:
Not in scope: data constructor ‘ExposePackageId’
Perhaps you meant ‘ExposePackage’ (imported from DynFlags) cabal: Error: some packages failed to install: ghc-mod-5.2.1.2 failed during the building phase. The exception was: ExitFailure 1
After applying the accepted answer (which seemed to install ghc-mod), running gch-mod gives the following:
> ghc-mod check x.hs
cabal-helper-wrapper: Installing a private copy of Cabal, this might take a
while but will only happen once per Cabal version.
If anything goes horribly wrong just delete this directory and try again:
/Users/mark/.ghc-mod/cabal-helper
If you want to avoid this automatic installation altogether install version
1.22.0.0 of Cabal manually (into your user or global package-db):
$ cabal install Cabal-1.22.0.0
...In order, the following would be installed:
filepath-1.3.0.1 (latest: 1.4.0.0) (new version)
directory-1.2.2.1 (new version)
process-1.2.3.0 (reinstall) changes: directory-1.2.2.0 -> 1.2.2.1,
filepath-1.4.0.0 -> 1.3.0.1
Cabal-1.22.0.0 (latest: 1.22.2.0) (new version)
cabal: The following packages are likely to be broken by the reinstalls:
ghc-7.10.1
Cabal-1.22.2.0
Use --force-reinstalls if you want to install anyway.
cabal-helper-wrapper: Installing Cabal version 1.22.0.0 failed.
nYou have two choices now:
- Either you install this version of Cabal in your globa/luser package-db
somehow
n- Or you can see if you can update your cabal-install to use a different
version of the Cabal library that we can build with:
$ cabal install cabal-install --constraint 'Cabal > 1.22.0.0'
nTo check the version cabal-install is currently using try:
$ cabal --version
ghc-mod: readCreateProcess: /Users/mark/.cabal/libexec/cabal-helper-wrapper "/Users/mark/work/haskell/ixberg/dist" "entrypoints" "source-dirs" "ghc-options" "ghc-src-options" "ghc-pkg-options" "--with-ghc=ghc" "--with-ghc-pkg=ghc-pkg" "--with-cabal=cabal" (exit 1): failed
Strangely, it wants the version of Cabal that is currently installed:
> cabal --version
cabal-install version 1.22.0.0
using version 1.22.0.0 of the Cabal library
Edit (August 2015) Better fix
A better command line tool for installing Haskell binaries and libraries by the awesome FPComplete group called stack means you can install ghc-mod with stack install ghc-mod (outside a project to make it global) and it will just work. The binary will be installed to ~/.local/bin and should be put on your path so your editor can find it.
I will leave the below for anyone who wishes to know what cabal Hell really meant.
Problem With DanielG's Fork
I asked on the Haskell reddit and NihillstDandy explained that the GHC for Mac OS X does not register the Cabal library. This is not true for your install from http://ghcformacosx.github.io/. It does register the Cabal library.
ghc-mod needs the cabal library to work, but it does not compile with the cabal library. Instead it compiles with cabal-helper and that looks to see if you have a registered version of the cabal library. If it does not find any then cabal-helper-wrapper will install a private copy and in this case it tired to install the same version as what cabal-install was compiled with, cabal-1.22.0.0.
When I installed DanielG's Fork it worked for my current project, but after testing it in other projects I am getting the same error you are. This is a problem with the fork and not Haskell (as far as I can tell).
Original Answer
So, while I was putting this post together ghc-mod was fixed for GHC-7.10. Thanks to DanielG!
git clone https://github.com/DanielG/ghc-mod
cd ghc-mod
cabal install -j4
And if you get errors that say "setup-Simple-Cabal-1.22.2.0-x86_64-osx-ghc-7.10.1: The program 'happy' version
>=1.17 is required but it could not be found."
cabal install happy -j4
The same for any other problems and it should work. (Although you have happy installed, so it should just work).
The rest of the post is on how to downgrade the cabal executable, also known as cabal-install, to version 1.20.0.3. Although you could really use this to downgrade to any version. Since there is a working fork of ghc-mod that works with GHC-7.10 and cabal-1.22 you do not need to downgrade to fix ghc-mod.
I'm just leaving the rest of the post up here since, unfortunately, this is a problem with Haskell as a whole. Halcyon and nix are ways to deal with Haskell's shortcomings in this regard.
How to downgrade Cabal in Haskell
When I wrote this post ghc-mod, nor any fork, compiled with GHC-7.10 and versions below 7.10 broke with cabal-1.22 sandboxes.
However, even if you compile ghc-mod with GHC-7.8.4 (the version before 7.10) and cabal-1.20.0.3 you still cannot use ghc-mod inside a sandbox created by cabal-1.22 and above. So the only way to use ghc-mod is to either downgrade your entire system to cabal-1.20.0.3 or don't use sandboxes. This means you can still use GHC-7.10, but you have to use the older version of cabal. That is unless you want to wait until the convener or someone else fixes it for GHC-7.10. Its been over a week already, but some kind Haskell programmer fixed it in a fork (see above).
If this is something you still want here is how to compile ghc-mod with GHC-7.8.4 and cabal-1.20.0.3. Also, I replace the executable cabal-1.22 with the older cabal-1.20.0.3. Note, it does not matter what directory you download the sources to.
download GHC-7.8.4 source for your OS from here
tar -xf path_to_zipped_source
cd path_to_ghc-7.8.4
The next steps will install ghc-7.8.4 as ghc-7.8.4 in the same folder as ghc-7.10 is install for you. The -j4 is to tell make to use 4 threads to compile it.
./configure
make install -j4
To get the correct version of cabal we can just ask cabal to get it.
cabal get cabal-install-1.20.0.3
cd cabal-install-1.20.0.3
Now to install cabal with ghc-7.8.4. Here cabal-1.22 will pull all the decencies and should give you some warning about installing another version of the cabal library (not to be confused with cabal-install), this should not cause problems.
cabal --with-compiler=ghc-7.8.4 install
So now you should have cabal-1.20.0.4 installed, but not on your path. It will be in ~/.cabal/bin. We need to make this global, so remove cabal-1.22 (it only removes the symlink).
rm `which cabal`
And create the symlink to cabal-1.20.0.4. Btw, you will need to remove any sandboxes you made with cabal-1.22 and remake them with cabal-1.20.0.4.
If you do not have realpath you can just type in the full path of cabal. I use it for connivence.
cd ~/.cabal/bin
ln -s `realpath cabal` /usr/local/bin
Now this is how I compiled ghc-mod on my mac (you may run into your own problems). I'm not sure why cabal couldn't do it in one call, but this worked in the end.
cabal --with-compiler=ghc-7.8.4 install happy
cabal --with-compiler=ghc-7.8.4 install haskell-src-exts-1.16.0.1
cabal --with-compiler=ghc-7.8.4 install hlint-1.9.19
cabal --with-compiler=ghc-7.8.4 install ghc-mod
Now you should be able to call ghc-mod from anywhere. To test it just type ghc-mod after you have cabal sandbox init. If it does not throw any errors then your in the clear.
The version of executable cabal that is used to configure this project should be the same as the version of the global Cabal package.
It's easier to install a compatible version of cabal-install than Cabal as follows:
$ ghc-pkg list | grep Cabal
Cabal-1.22.2.0
$ cabal install cabal-install-1.22.2.0
Or build one in sandbox and replace/shadow the original one.
Then don't forget to re-configure the project with the new cabal:
$ cabal clean && cabal configure
Now the ghc-mod should works.
If Cabal-1.22 isn't registered (ghc-pkg list cabal), the cabal-helper-wrapper will install a private copy because it needs the library installed to work, but it doesn't want to stomp on anything you have that might break by upgrading Cabal directly.
GHC for Mac OS X doesn't register the Cabal library, it comes bundled with a version of cabal-install built against it.