Nix vs asdf for Elixir version management

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I’m a relatively happy Nix user in general, including on OSX and as a Linux desktop via NixOS, but I would be very unhappy teaching most people to use it, even those who are able to effectively adapt to both Elixir and ASDF. It’s a lot to ask for little return unless you already find it academically interesting. It has a lot of parallels in my mind to my use of Emacs - I personally find it very powerful and compelling, but struggle to articulate well to others who are skeptical, or who have different levels of tenacity in the face of ~user-unfriendly~ complex software.

I will also say that very specifically the abstractions used in the BEAM packaging within nixpkgs are over-abstracted from my POV. They are probably very useful/powerful to the internal/official maintainers, but are sort of a nightmare to consume as someone who is literate with the syntax but not an expert. If you’re not sure what I mean, try to figure out how to use a Nix overlay or shell.nix to install a particular patch release of Erlang and of Elixir, without it having been packaged already. You can’t use a simple override, nor have I found an easy way to otherwise “patch” the URL and checksum of the target download like I can with other languages’ Nix packaging.

I ultimately fell away from using Nix specifically for the BEAM ecosystem and back to ASDF, even when I persist with Nix elsewhere.

For those unfamiliar, here’s an example of shell.nix content:

# 2018-06-26 11:30
# https://d3g5gsiof5omrk.cloudfront.net/nixpkgs/nixpkgs-18.09pre143801.5ac6ab091a4/nixexprs.tar.xz
with import <nixpkgs>{};

let
  erlang = beam.packages.erlangR21.erlang;
  elixir = beam.packages.erlangR21.elixir;
  nodejs = pkgs.nodejs-10_x;
  yarn = pkgs.lib.overrideDerivation pkgs.yarn (attrs: rec {
    buildInputs = [pkgs.makeWrapper nodejs];
  });
in

stdenv.mkDerivation rec {
  name = "my_elixir_project";
  version = "0.1.0";
  buildInputs = [
    erlang
    elixir
    nodejs
    yarn

    # phoenix_live_reload
    pkgs.darwin.apple_sdk.frameworks.CoreFoundation
    pkgs.darwin.apple_sdk.frameworks.CoreServices

    # postgrex
    pkgs.postgresql100

    # developer tools
    pkgs.direnv
    pkgs.gitMinimal
    pkgs.hex2nix
  ];
}
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