running nix build . i get
> Error:
>
> <no location info>: error:
> Could not load module ‘Crem.Example.TwoSwitchesGate’
> It is a member of the hidden package ‘crem-0.1.0.0’.
> You can run ‘:set -package crem’ to expose it.
> (Note: this unloads all the modules in the current scope.)
i think it's because the TwoSwitchesGate module is defined in an lhs file, and perhaps something special has to be done to make nix find that :/