I have a cabal file with a custom build to (calls Setup.hs to perform some preprocessing). But Setup.hs imports Project.Preprocessor, which is under src as show below.
project.cabal
Setup.hs
src/Project/Preprocessor.hs
src/Project/OtherFiles...
This fails since src is not included (as in runghc -isrc Setup.hs build).
dist\setup\setup.hs:3:18:
Could not find module Project.Preprocessor
...
Is there any way to include an extra source directory for build process?
I.e. like runghci -isrc Setup.hs (but from cabal build).
EDIT: I did verify that runghc -isrc Setup.hs build executes. :-)
Thanks!
Related
By default I build my project without nix, and executable is linked statically. But when building with nix, I want to link it dynamically instead. So I added a switch to myproj.cabal:
flag dynamic
description: Build only dynamic binaries
default: False
executable RunMe
ghc-options: -O2 -Wall
if !flag(dynamic)
ghc-options: -optl-static -static
Now I can build the project with
stack --nix --nix-packages=zlib install --flag myproj:dynamic
To avoid passing command line options every time, I created shell.nix:
{ghc}:
with (import <nixpkgs> {});
haskell.lib.buildStackProject {
inherit ghc;
name = "myproj";
buildInputs = [ zlib ];
}
Now, I don't know how to pass flag to cabal from nix file. Based on buildStackProject definition, I tried setting buildPhase, e.g.
haskell.lib.buildStackProject {
...
buildPhase = "stack build --flag=myproj:dynamic";
}
but it doesn't seem to change anything. How can I pass the flag to cabal from the nix file?
Unfortunately, the stack nix integration is rather backwards. It doesn't use nix to build your package (despite the very misleadingbuildStackPackage), just to create an environment with GHC and native dependencies. You have to use stack itself to build the project, and since stack will run cabal, it should still work with the flag. The stack nix integration will not generate a .nix file with the dependencies resolved by stack, so you can't build your project with nix-build and there's no point in entering nix-shell. You would have to use a tool like stack2nix or stackage2nix for that.
So to recap. The shell.nix above looks fine. Add this to your stack.yaml:
nix:
shell-file: shell.nix
And build the project with stack:
stack --nix --flag myproj:dynamic
That should build the project with the flag as usual, but use GHC and zlib from nix.
I try to generate documentation for my executable using cabal haddock. My project structure looks like this:
~/.../project_name
project_name.cabal
Setup.hs
src/
Main.hs
Data/
...
test/
MainTestSuite
...
When I run cabal haddock --executable it fails with the following error message:
module ‘projects-0.1.0.0:Main’ is defined in multiple files: dist/build/tmp-8215/src/Main.hs
dist/build/tmp-8215/./Setup.hs
The Source.hs file has these contents:
import Distribution.Simple
main = defaultMain
The ghc Version is 7.8.3 and the haddock version is 2.14.3.
My project structure is as follows:
~/.../project_name
project_name.cabal
Setup.hs
src/
Main.hs
Data/
...
test/
MainTestSuite
...
I have (amongst others) the following lines in my project.cabal:
build-type: Simple
...
executable project_name
main-is: Main.hs
...
hs-source-dirs: src
When I cabal configure (works fine) and then cabal build I get the error message:
cabal: can't find source for Setup in src, dist/build/autogen
It works when I put Source.hs in src but this seems messy to me and I haven't seen this in other projects, where Source.hs is always in the project root. How do I get cabal to find Source.hs?
As an aside: What's the purpose of Source.hs anyways?
The problem was caused by accidently adding the Source file as a dependency in other-modules in the cabal-file of the project ... that caused all the trouble.
hs-source-dirs: ., src comes to mind as a fast fix.
That's what my projects use, and I generate my cabal files automatically (so I suppose that's the default).
I have a src directory. In this directory I have Main.hs file and Test directory. In the Test directory I have Test.hs module. I need to compile it with cabal.
In my cabal file I have:
Executable main
-- .hs or .lhs file containing the Main module.
Main-is: src/Main.hs
and
-- Modules not exported by this package.
Other-modules: Test.Test
When I do cabal configure it's OK, but when I try to cabal build I get the following error:
cabal build
Preprocessing executables for main-0.0.1...
cabal: can't find source for Test/Test in ., dist/build/autogen
How can I correctly build Main.hs and some other directories with .hs files?
Thank you.
If Test.Test is defined in src/Test/Test.hs, you need
hs-source-dirs: src
in the Executable section of your Cabal file. Note that your main-is file path should be relative to the source directory, so in this case, you should change it to Main.hs.
According to the wiki entry,
It packages up the files needed to build the project
I have a simple executables-only .cabal project, which basically contains
Executable myprog
hs-source-dirs: src
main-is: MyMain.hs
and is made up of some additional .hs files below src/ beyond src/MyMain.hs. E.g., src/Utils.hs and a few others.
cabal build has no problems building myprog, and compiles the required additional .hs files below src/, but cabal sdist does not, thus creating a dysfunctional source-tarball. What am I doing wrong? How do I tell cabal to include all source files below hs-source-dirs?
As a side-note, with GNU Autotools, there was a make distcheck target, which would first build a source-tarball, and then try to build the project via the newly generated source-tarball, thus ensuring everything's ok. Is there something similar for cabal, in order to make sure my source-tarball is sound?
You should list the other Haskell files in the .cabal file, inside the Executable stanza.
other-modules: Utils AFewOthers
The distribution only includes source files that are listed in your .cabal file. Cabal has no other way to detect which source files are in your package. You could still build because cabal build calls ghc --make, and ghc will find and compile all the source files it needs.