Getting Nix and Miso set up on macOS Catalina

nix-miso-macos-catalina.md

Setting up Nix

Following this thread on getting Nix set up on macOS Catalina, there's a few steps involved (assuming you have no /nix folder):

1. Set up nix folder: echo 'nix' | sudo tee -a /etc/synthetic.conf

2. Reboot for it to take effect

3. Create an APFS volume for Nix (might need to use a different diskX number, check diskutil list for more):

   sudo diskutil apfs addVolume disk1 APFSX Nix -mountpoint /nix
   sudo diskutil enableOwnership /nix
   sudo chflags hidden /nix  # Don't show the Nix volume on the desktop
   echo "LABEL=Nix /nix apfs rw" | sudo tee -a /etc/fstab

4. Install Nix: sh <(curl https://nixos.org/nix/install) --daemon

At this point, everything works perfectly. However, the nix daemon will fail to start after rebooting. It's simple enough to fix, and I've detailed a workaround in #3125.

Setting up Miso

We are now ready to set up Miso:

nix-env -iA cachix -f https://cachix.org/api/v1/install
cachix use miso-haskell
cd ~/GitHub/Clones # Assumes you have a folder set up for clones
git clone https://github.com/dmjio/miso
cd miso/sample-app
nix-build
open ./result/bin/app.jsexe/index.html

For the recommended development with ag -l | entr sh -c 'cabal build', set up the tools via:

nix-env -iA cabal-install entr ag -f '<nixpkgs>'

If you are still inside miso/sample-app, you can jump into a nix shell with nix-shell -A env, and then run ag -l | entr sh -c 'cabal build'.

Miso and Live Reload

It's possible to get live reloading and support for ghcid, by using the sample-miso-jsaddle app instead. Let's set it up:

cd ~/GitHub/Clones/miso/sample-app-jsaddle
nix-shell --run reload # or build a release with: nix-build -A release

This works by switching between GHC and GHCJS depending on the target.

In addition, I have to do the following in boot:

sudo diskutil mount -mountPoint /nix /dev/disk1s7
launchctl load /Library/LaunchDaemons/org.nixos.nix-daemon.plist && launchctl start org.nixos.nix-daemon
source /etc/zshrc