botiut/stack-arm.org

Installing stack on ARM bit

Why stack on ARM

People might want to run Haskell applications on ARM devices like a Raspberry Pi. The Haskell compiler has supported the architecture through LLVM for a couple of year now, as well as the builtin dependency manager, Cabal. However the dependency management of Cabal is system-wide (or at least user wide) and, because all packages interact with each other, it can pose problems with compatibility.

That is the problem that stack solves by allowing for reproducible, isolated environment for each project, and a lot of projects now use stack for their dependency and version management.

However stack does not provide any build for arm systems, we thus need to install it another way

First step, getting a compiler

Whereas stack does not provide an ARM build, GHC does. so we first head to the GHC download page and get the latest build. Usually the archive is for Debian, but should work for any GNU libc based distribution.

At time of writing stack lts snapshots don't use GHC 9 yet so the used version is 8.10.7.

This should leave you with an archive like ghc-8.10.7-aarch64-deb10-linux.tar.xz (Keep that archive around, we will need it for stack later on).

We are now going to extract and setup a minimal Haskell environment

tar xvf ghc-8.10.7-aarch64-deb10-linux.tar.xz
cd ghc-8.10.7
./configure --prefix=$HOME/.cabal
make install

Next grab the latest cabal binary for AArch64 from Cabal download page (usually tagged as for Debian but should work on any GNU Libc system). Put the contained executable in $HOME/.cabal/bin

Finally put $HOME/.cabal/bin in your PATH.

You now have a minimal Haskell installation in your path, we are now ready to move to the next step

Install a stack bootstrap environment

Now that we can compile some Haskell things, lets install a bootstrap stack installation. It is not the final one, because this one is tied to a cabal version instead of a stack snapshot

To do that we simply tell cabal to install stack

cabal install stack

This compilation will take a bunch of memory, and most likely a while, if on a system with limited RAM, you might want to unmout the tmpfs at /tmp and increase the swap size in order to have around 4GB free

Register the compiler with stack

Remember when I said to keep the GHC archive around because we will need it later, well that later is now. Move that archive to a folder where you'll most likely not accidentally delete it, here I'll use ~/ghc

Once the archive is stored in that folder, open your stack configuration (~/.stack/config.yaml) and add the following

setup-info:
  ghc:
    linux-aarch64-tinfo6:
      8.10.7:
        url: "~/ghc/ghc-8.10.7-aarch64-deb10-linux.tar.xz"

Finaly, bootstrap stack with itself

Now we need to reinstall stack with itself, to untie it from the temporary setup.

stack setup
stack install stack

Once again this will take a lot of both memory and time.

Clean up

You can now remove the ~/.cabal/bin folder and add the ~/.local/bin folder to the path, that is where stack will install binaries.

You can also delete the ~/.cabal as it is no longer needed

Once this is done, you now have a fully functionnal stack setup.

If in the future you need an additionnal compiler version you can add its archive to the compilers folder and register it with stack the same way as previously done.