In reply to @woobilicious:matrix.org
Is there anyway to "export" a build plan for haskell apps based on the nixpkgs version? trying to think how to compile my code for windows, and cabal obvious isn't going to pull in the exact same versions without some hints. I guess I could look at cross compiling using mingw64 version of ghc in nixpkgs, but that might just be a huge headache.

is there a function to parse a flake lockfile into a set?

let sources = parseFlakeLock (builtins.readFile ./flake.lock);

something like this

Yes, in fact flake-compat is based on this principle. See examples here: https://github.com/nix-community/flake-compat

Basically: builtins.fromJSON (builtins.readFile ./flake.lock);

so I'm just doing this rn

  # fetch from flake.lock
  with (builtins.fromJSON (builtins.readFile ../flake.lock));
  fetchFromFlakeLock = args:
    fetchFromGitHub {
      inherit (args.locked) owner repo rev;
      hash = args.locked.narHash;
    };
  servant = fetchFromFlake (nodes.servant);