gistfile1.txt

```
❯ cat package.json                                                                                                /tmp/intelephense
{
  "name": "intelephense",
  "version": "1.3.4"
}

❯ node2nix --nodejs-12 package.json                                                                               /tmp/intelephense
fetching local directory: ./. from .

❯ nix repl '<nixpkgs>'
nix-repl> intelephene = import ./default.nix {}
nix-repl> :b intelephene.package

this derivation produced the following outputs:
  out -> /nix/store/ip7ymhafh34a74z0vw6c3sf70mfd6ani-node_intelephense-1.3.4
```

So you should be able to do something like this in your configuration.nix;

```
let
    intelephene = import ./default.nix {};  
in

{
    environment.systemPackages = [ intelephene.package ];
}
```