introduce store and store objects without file system details
introduce store and store objects without file system details

this leaves open implementation details, especially about store paths
and file system objects, and allows explaining them together were it is
more appropriate. also leaves room to carefully introduce the key
insight behind Nix: applying results from programming language theory to
the operating system paradigm of files and processes.

NixOS/nix,NixOS/nix,NixOS/nix,NixOS/nix,NixOS/nix