Reflex Tutorial Upgrade

In the Reflex Package Versions blog entry, I tried to manually upgrade the Reflex FRP calculator tutorial to use the latest release of Obelisk. Building the project failed with an unknown error, and I was unable to build verbosely due to a bug. A friend emailed me with some tips, and this blog entry documents my continued efforts to upgrade the tutorial.

When I tried upgrading the tutorial to use the latest version of Obelisk, I saw that the .obelisk/impl directory is itself a “thunk.” My friend pointed out that the usual way to “update” this is to use an ob thunk update command. He suggested using the following command.

$ ob --no-handoff thunk update .obelisk/impl --branch master

I have not used the --no-handoff option yet, so I looked it up. It is documented as follows.

$ ob --help
...
  --no-handoff             Do not hand off execution to project-specific
                           implementation of this command
...

When I am in a project directory and run ob (without using --no-handoff), the command builds the ob command using the project configuration (which may be cached) and runs it. That is the behavior that I have been seeing. With --no-handoff, the ob command in my environment (Nix profile) is used instead.

I ran the above thunk update command and confirmed that it updates the Obelisk thunk to use the latest revision on the master branch. It of course does not change any of the other files that I manually merged from the new project template.

With the Obelisk configuration updated, it was time to execute ob run. My friend indicated that it should take about thirty minutes in this case. I executed ob run, and it took almost exactly one hour to fail with the same error message that I saw before. Regarding timing, it is feasible that my friend’s workstation is more than twice as fast as my laptop.

My friend also said that the reflex-dom-core error that I mentioned in the Nix Reproducibility blog entry should not occur if the cache is used! Since I am unable to use --verbose, I cannot see what the actual error is that is causing my tutorial builds to fail. Perhaps the cache is not being used, and perhaps I would not get the error if cache is used? It is a shot in the dark.

According to the Installing Obelisk instructions, the cache is configured on non-NixOS system in the /etc/nix/nix.conf configuration file. (Note that the “see full list” link outdated; the Nix manual is now spread out across many pages instead of all on a single page.) Is this configuration file used by single-user Nix installs? I have not been able to find a definitive answer to this. There is no indication that it is not used, and I have not been able to find any documentation about configuring single-user installs in particular. Discussion about this configuration file indicates that there is no default /etc/nix/nix.conf when doing a single-user install, but that it should be created manually, which is what I did.

Perhaps I should try a multi-user installation to see if that changes anything. In January, I aborted my attempt to use a multi-user installation after getting permissions errors (see Uninstalling Multi-User Nix). Perhaps those issues were due to my Arch Linux host, and using a more “enterprise” distribution like Ubuntu would allow me to avoid them. If I need to configure a system with a different OS, however, I may as well use NixOS…