Following the instructions to set up an new environment gives an error.

[Ryan Booker]

When setting up a new environment, I'm seeing the following error.

nix 2.11.0

Firstly the instructions as is don't work, nix flake init needed the -t option. Once passing that, calling nix develop failed with the following error:

Any guidance much appreciated.

% nix develop
error: attribute 'derivation' missing

       at /nix/store/sisjjm5z7812kw5hg19niq26kk9h766c-source/flake.nix:20:11:

           19|           }:
           20|           (self.lib.getRubyVersionEntry rubyVersion).derivation {
             |           ^
           21|             inherit pkgs;

[Ryan Booker]

Solved: It is common for .ruby-version to contain an "incomplete" version numbers. e.g. 2.6. This will fail when trying to look up the version in nixpkgs-ruby, as it requires a M.m.p version number.

Update .ruby-version to contain a fully specified version. e.g. 2.6.10 or 2.6.*.