I've got the following question:
I've got two Haskell libraries that depend on each other, and both libraries are managed by cabal. The corresponding cabal files look like this:
Library 1:
name: Lib1
version: 0.1
cabal-version: >=1.2
build-type: Simple
author: Matthias
library
hs-source-dirs: src
build-depends:
base >= 4,
Lib2
ghc-options: -Wall
exposed-modules: <...>
Library 2:
name: Lib2
version: 0.1
cabal-version: >=1.2
build-type: Simple
author: Matthias
library
hs-source-dirs: src
build-depends:
base >= 4,
Lib1
ghc-options: -Wall
exposed-modules: <...>
Installing one of the libraries (here library 2) with cabal install works:
Resolving dependencies...
In order, the following will be installed:
Lib2-0.1 (reinstall)
Warning: Note that reinstalls are always dangerous. Continuing anyway...
Configuring Lib2-0.1...
Building Lib2-0.1...
Preprocessing library Lib2-0.1...
Registering Lib2-0.1...
Installing library in
C:\Users\Matthias\AppData\Roaming\cabal\Lib2-0.1\ghc-7.4.2
Registering Lib2-0.1...
But trying to install the other library (here library 1) with cabal install results in a dependency error:
Resolving dependencies...
cabal.exe: Could not resolve dependencies:
trying: Lib1-0.1 (user goal)
next goal: Lib2 (dependency of Lib1-0.1)
rejecting: Lib2-0.1/installed-aa4... (package is broken)
Is there any way to handle two such libraries that depend on each other so that I don't get dependency errors or is cabal simply not able to handle such a case properly?
As the others have said, circular dependencies are never going to work in Cabal. It's hard enough to compile modules with circular dependencies, but packages are a hopeless cause.
It can be annoyingly difficult sometimes, but the only real solution is to find a way to break the circular dependency somehow.
Related
I want to build the haskell bindings for z3 in a Cabal project, the following is the minimum (faulty) example:
Using a project initialized by cabal init:
test/
- Main.hs
- Setup.hs
- CHANGELOG.md
- test.cabal
With modified test.cabal:
cabal-version: 3.0
name: z3-test
version: 0.1.0.0
extra-source-files: CHANGELOG.md
executable test
main-is: Main.hs
build-depends: base >=4.14 && <4.15
, z3 ^>=408.2
default-language: Haskell2010
Z3 binaries are located at C:\z3-4.8.5-x86-win.
Z3-bindings are installed:
cabal v1-install z3 --extra-lib-dirs=C:/z3-4.8.5-x64-win/bin --extra-include-dirs=C:/z3-4.8.5-x64-win/include -v3
All the requested packages are already installed:
z3-408.2
Use --reinstall if you want to reinstall anyway.
Now building the project using:
cabal v2-build --extra-lib-dirs=C:/z3-4.8.5-x64-win/bin --extra-include-dirs=C:/z3-4.8.5-x64-win/include -v3
Results in the error:
Build profile: -w ghc-8.10.2 -O1
In order, the following will be built (use -v for more details):
- z3-408.2 (lib) (requires build)
- z3-test-0.1.0.0 (exe:test) (first run)
Starting z3-408.2 (lib)
Failed to build z3-408.2. The failure occurred during the configure step.
Build log (
C:\cabal\logs\ghc-8.10.2\z3-408.2-1722a25655334afbca91ac935f14ff0d20ccf8c4.log
):
Configuring library for z3-408.2..
cabal.exe: Missing dependency on a foreign library:
* Missing (or bad) header file: z3.h
* Missing (or bad) C library: z3
This problem can usually be solved by installing the system package that
provides this library (you may need the "-dev" version). If the library is
already installed but in a non-standard location then you can use the flags
--extra-include-dirs= and --extra-lib-dirs= to specify where it is.If the
library file does exist, it may contain errors that are caught by the C
compiler at the preprocessing stage. In this case you can re-run configure
with the verbosity flag -v3 to see the error messages.
If the header file does exist, it may contain errors that are caught by the C
compiler at the preprocessing stage. In this case you can re-run configure
with the verbosity flag -v3 to see the error messages.
cabal.exe: Failed to build z3-408.2 (which is required by exe:test from
z3-test-0.1.0.0). See the build log above for details.
How can I build a project with the z3 bindings?
Note that:
GHC version = 8.10.2
Cabal version = 3.2.0.0
I can only use cabal
Using cabal install ... or cabal v2-install ... results in Cannot build .. z3 because none of the components are available to build:
I'm using inline-c and I have two C files that I'd like to call in the Haskell code. In the Cabal file, there are:
include-dirs: cbits
, /usr/local/include
c-sources: cbits/genann.c
In the Cbits directory, there's also genann.h
I can build and run the project without problem but when I do cabal install, the compiler complain that it can't find the C header file.
I checked the Cabal manual and added the following options:
includes: cbits/genann.h
install-includes: cbits/genann.h
This time I got:
Configuring executable 'inline-gsl' for inline-gsl-0.1.0.0..
cabal-3.6.2.0: Missing dependency on a foreign library:
* Missing (or bad) header file: cbits/genann.h
This problem can usually be solved by installing the system package that
provides this library (you may need the "-dev" version). If the library is
Where is wrong here? Do I need to compile the C code into object code and put them in the system?
The complete Cabal file:
cabal-version: 2.4
name: inline-gsl
version: 0.1.0.0
-- A short (one-line) description of the package.
-- synopsis:
extra-source-files: CHANGELOG.md
executable inline-gsl
main-is: Main.hs
build-depends: base ^>=4.14.3.0
, inline-c
, vector
, massiv
, array
, bytestring >= 0.10
, template-haskell
hs-source-dirs: app
pkgconfig-depends: glib-2.0, gtk4, gsl
default-language: Haskell2010
extra-libraries: m, tensorflow
extra-lib-dirs: /usr/local/lib
cc-options: -Wall -m64 -O4
include-dirs: cbits
, /usr/local/include
includes: cbits/genann.h
install-includes: cbits/genann.h
c-sources: cbits/genann.c
I can build and run the project without problem but when I do cabal install, the compiler complain that it can't find the C header file.
I believe this indicates that the problem is that your header files are not included in your package source tarballs (sdist). You need to list all non-Haskell source files under the extra-source-files field in your cabal file:
extra-source-files: CHANGELOG.md, cbits/genann.h, cbits/genann.c
I have a Haskell library which exports several modules. I compile that library with both GHC and GHCJS. I'm using stack to build the library. One of those modules depends on reflex-dom. The issue is that I am not able to compile reflex-dom on GHC due to not being able to link gtk+3 on OSX. As such, I'd like to exclude that library if the compiler is GHC. How can I achieve that?
exposed-modules:
MyLib.Foo
MyLib.Bar
MyLib.App.Backend.Reflex
MyLib.App.Backend.Gloss
...
build-depends:
base ...
reflex-dom >= 0.2 && <0.3
While you may not want to do this, the way to do this is described in the "configurations" section of the cabal user manual:
https://www.haskell.org/cabal/users-guide/developing-packages.html#configurations
In particular, you should be able to write the relevant sections as such:
exposed-modules:
MyLib.Foo
MyLib.Bar
MyLib.App.Backend.Reflex
MyLib.App.Backend.Gloss
if !impl(ghc)
exposed-modules:
OtherModule
build-depends: etc, etc, etc
if !impl(ghc)
build-depends: etc1, etc2
I'm running my first "cabal test" for Haskell, but I get the error:
Package has never been configured. Configuring with default flags. If this
fails, please run configure manually.
Resolving dependencies...
Configuring sample-0.1.0.0...
cabal: At least the following dependencies are missing:
base ==4.7.*
sampel.cabal:
-- Initial sample.cabal generated by cabal init. For further
-- documentation, see http://haskell.org/cabal/users-guide/
name: sample
version: 0.1.0.0
build-type: Simple
cabal-version: >=1.10
executable SampleTest
main-is: SampleTest.hs
build-depends: base >= 4.7 && <4.8, HUnit >=1.2 && <1.3
hs-source-dirs: test, src
default-language: Haskell2010
Any help appreciated.
Versions of GHC come bundled with versions of base. GHC 7.10.2 uses base 4.8.1.0.
Your cabal must be using a slightly out of date template....
You should either change the range of acceptable base version (as you did in your comment above), or use a different version of GHC.
I've been working on this Haskell project, and I have a cabal file for it. Now, my project is structured as a library that implements a simple interpreter. I also have a very short Main file which needs to be build into an executable to call the library. What I want to do is:
1) compile the library and expose some of the modules
2) compile the executable
I have a cabal file that works and seems to do this. The problem is that when it compiles the executable it recompiles all the modules which have already been compiled in step (1). I don't quite understand why it does this - is there any way to stop it, short of creating two separate cabal files?
I don't really want to create two separate cabal files, because cabal doesn't seem to like having both the cabal files in the same directory, and I don't really want to set up a separate project directory for the second step, since it basically just amounts to compiling a single file.
cabal-version: >= 1.6
build-type: Simple
name: HaSC
version: 0.2.3
license: OtherLicense
category: Language
author: Chris B
maintainer: Chris B
copyright: Chris B 2010 - 2011
synopsis: (HA)skell (S)ound (C)hange applier (HaSC) library
description: HaSC implements a little language for applying sound changes to words
homepage: http://www.chrisdb.me.uk/redmine/projects/haskell-sound-change
stability: Alpha
data-files: doc/HaSCDoc.pdf
license-file: LICENSE
library
build-depends:
base >= 4.3,
containers >= 0.3,
parsec >= 3,
parallel >= 3.1,
deepseq >= 1.1,
mtl >= 1.1,
transformers >= 0.2,
text >= 0.10,
text-icu >= 0.6.3,
pretty >= 1,
directory >= 1.1,
filepath >= 1.2
hs-source-dirs: src
exposed-modules: HaSC.IO.Disk,
HaSC.IO.Memory,
HaSC.Exec
other-modules: HaSC.AST,
HaSC.IO,
HaSC.IdentMap,
HaSC.Parse,
HaSC.Regex,
HaSC.Representation,
HaSC.Transformations,
HaSC.Search,
HaSC.State
executable HaSC
GHC-Options: -rtsopts
hs-source-dirs: src
main-is: Main.hs
In your executable section, add the library in Build-Depends so that the executable depends on the library.
There's a small gotcha, though: You also have to move the Main.hs of the executable (and any other source files specific to the executable) to a different subdirectory and specify a different Hs-Source-Dirs so that it doesn't pick up the library modules by being in the same folder.
executable HaSC
Build-Depends: HaSC
Main-Is: Main.hs
Hs-Source-Dirs: foo -- Directory you moved Main.hs to
For this to work, you will need to specify Cabal-Version >= 1.8. See Cabal ticket #89 for the details.