Cross Platform Haskell Console Application that outputs Hello World on iOS, Android and Desktop. This is merely a proof-of-concept, showing how to target several platforms from a single Haskell codebase.

For all platforms:

• GHC (tested with 7.10.2)
• Cabal (tested with 1.22.6)

For iOS:

• Machine with OSX installed (tested on El Capitan)
• Xcode (tested with 7.0.1)

For Android:

• Docker (1.6 or greater is required)
• The android platform tools for easy installation of the .apk file

First make sure to have jobs: $ncpus commented out in ~/.cabal/config.

Then run the following commands:

git clone --recursive https://github.com/EDeijl/CPHConsoleApp.git
cd CPHConsoleApp
./setup.sh

The setup.sh script installs ghc-ios dependencies (when on OSX) and creates a docker container for Android builds.

Run ./prepare-ios-all.sh to build the Haskell code of the project. This will put several library (.a) and header (.h) files in the Xcode project directory (./platforms/ios/).

Use Xcode to open the project and check if the lib directory in your project contains HaskellActivity_stub.h and CPConsoleAppStaticLib.a. It is no problem these files also exist in the root of the project. If the library and header files cannot be found in your project, then click File -> Add files to project, select the lib folder and make sure that Add to targets is enabled. In case you do not see Add to target, click options at the bottom of the file open dialog.

In the HaskelliOS.xcconfig (which can be found in the Xcode project folder), the HEADER_SEARCH_PATHS variable should point to the include folder of your GHC installation, otherwise Xcode is not able to compile the project. The include folder is found in the location where your GHC is installed. It's path usually end with something like lib/ghc-7.10.2/include/ and contains several header files (we include HsFFI.h).

Xcode should now be able to build and run the project. If all went well, the application is automatically run. In the terminal output it will read "Hello World!".

For the Android build we make use of a Docker image that has all the dependencies for this project installed. The setup.sh script has already prepared this docker image for us.

With the following commands we start a container, build the .apk file, copy it to our host machine and remove the container so it will not conflict with the next build.

docker run --name apkbuilder -a stdout -a stdin android_build_env \
    /bin/bash -cl "cd CPConsoleApp; ./build-android.sh"
docker cp \
    apkbuilder:/home/androidbuilder/build/CPConsoleApp/platforms/android/bin/HaskellActivity-debug.apk .
docker rm apkbuilder

Now that we have the .apk on our local machine, we can install it on a device with adb install -r HaskellActivity-debug.apk. If a device is attached it will install the package there, otherwise it will try to run an emulator.

For desktop builds just run cabal configure -fdesktop and cabal build to generate an executable.

This is mainly a merger to two existing examples of compiling Haskell to mobile devices:

CJ van den Berg's ghc-android, android-haskell-activity and foreign-jni.

Sean Seefried's docker image for android builds and iOS build scripts in his Epidemic game.

Without their prior work this would have not been possible.

• Extend this example with SDL and networking