Plutus, Haskell, Nix, Purescript, Swift/Kotlin. laser-focused on FP: formality, purity, and totality; repulsed by pragmatic, unsafe, “move fast and break things” approaches


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Cake day: June 17th, 2023

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  • This is why I decided to learn Nix. I built dev environment flakes that provision the devshell for any language I intend to use. I actually won’t even bother unless I can get something working reliably with Nix. ;)

    For example, here’s a flake that I use for my Python dev environment to provide all needed wiring and setup for an interactive Python web scraper I built:

    
    {
      description = "Interactive Web Scraper";
    
      inputs = {
        nixpkgs.url = "github:NixOS/nixpkgs?ref=nixpkgs-unstable";
        utils.url = "github:numtide/flake-utils";
      };
    
      outputs = { self, nixpkgs, utils }: utils.lib.eachSystem ["x86_64-linux"] (system: let
        pkgs = import nixpkgs { system = system; };
      in rec {
        packages = {
          pyinputplus = pkgs.python3Packages.buildPythonPackage rec {
            pname = "pyinputplus";
            version = "0.2.12";
            src = pkgs.fetchPypi {
              inherit pname version;
              sha256 = "sha256-YOUR_SHA256_HASH_HERE";
            };
          };
    
          pythonEnv =
            pkgs.python3.withPackages (ps: with ps; [ webdriver-manager openpyxl pandas requests beautifulsoup4 websocket-client selenium packages.pyinputplus ]);
        };
    
        devShell = pkgs.mkShell {
          buildInputs = [
            pkgs.chromium
            pkgs.undetected-chromedriver
            packages.pythonEnv
          ];
    
          shellHook = ''
            export PATH=${pkgs.chromium}/bin:${pkgs.undetected-chromedriver}/bin:$PATH
          '';
        };
      });
    }
    
    




  • I’d look into building all of that in a flake just so you can encapsulate (and have a central version control of) all of your dependencies in case something does change.

    I’m a bit of a Nix dork but I tend to try and declare my entire dev stack in a flake so it can follow me to every machine. It offers some of the “it works on every machine” guarantees that Docker offers while also forcing the compilation of the stack to happen natively (or at least pulls in some content addressed cache that offers security by being the exact hash for the whole dependency graph). I like that

    Here’s how I used the Nix way to declare an interactive Python scraper the other day. With this method, I can lock dependencies between machines as a matter of course without having to use Docker:

    {
      description = “Weed Scraper”;
    
      inputs = {
        nixpkgs.url = “github:NixOS/nixpkgs?ref=nixpkgs-unstable”;
        utils.url = “github:numtide/flake-utils”;
      };
    
      outputs = { self, nixpkgs, utils }: utils.lib.eachSystem [“x86_64-linux”] (system: let
        pkgs = import nixpkgs { system = system; };
      in rec {
        packages = {
          pythonEnv =
            pkgs.python3.withPackages (ps: with ps; [ webdriver-manager openpyxl pandas requests beautifulsoup4 websocket-client selenium keyboard ]);
        };
    
        devShell = pkgs.mkShell {
          buildInputs = [
            pkgs.chromium
            pkgs.undetected-chromedriver
            packages.pythonEnv
          ];
    
          shellHook = ‘’
            export PATH=${pkgs.chromium}/bin:${pkgs.undetected-chromedriver}/bin:$PATH
          ‘’;
        };
      });
    } 
    




  • Yes for sure. Actually Nix is pretty long in the tooth and there are better implementations of Eelco’s brilliant idea. It’s just that they have a lot less effort, ubiquity, and hype behind them. GUIX is a good example of that. They literally can build an OS from scratch. I find Nix to be rock solid, so I stick with it. But, it’s an idea (all dependencies being content addressed in an immutable folder structure) to allow complexity that isn’t even achievable on FHS style systems.

    For example: THE main feature is that you could have a different version of say Python (for the sake of this example) installed for each dependency in your system and they would just work alongside each other due to their unique, hash based folder locations. Each folder is named based on the sha256 hash of the dependency graph, which has powerful implications. Because of this hash, they’re effectively hermetically sealed from each other and cannot step on each other. This is the very definition of Nix and taken far enough to define a whole OS is SUPER powerful concept.

    Shit, I’m rambling. Maybe I’ll pause to let you guide my rant. ;)