first commit

.gitignore

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+result

README.md

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+# Advent of Code 2021
+
+this flake builds a package containing a program for each problem in this years advent of code.
+
+## adding a problem
+
+create a folder in `code/src` for the problem, then add an entry with the following format into `code/aoc2021.cabal`:
+
+```
+executable aoc2021-XX
+   main-is: Main.hs
+   ghc-options: -O2 -Wall
+   hs-source-dirs: src/XX
+   build-depends: base
+   default-language: Haskell2010
+```
+
+## building
+
+your choice of:
+
+```
+nix shell git+https://git.p7.co.nz/thornAvery/aoc2021
+nix build git+https://git.p7.co.nz/thornAvery/aoc2021
+```
+
+or you can add the overlay defined in the flake

code/aoc2021.cabal

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+cabal-version: 1.12
+
+name:       aoc2021
+version:    0.0.0.1
+license:    MIT
+build-type: Simple
+
+synopsis: aoc2021 problem 01
+description: aoc2021 problem 01
+
+author: Thorn Avery
+maintainer: ta@p7.co.nz
+
+executable aoc2021-01
+   main-is: Main.hs
+   ghc-options: -O2 -Wall
+   hs-source-dirs: src/01
+   build-depends: base
+   default-language: Haskell2010

code/src/01/Main.hs

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+module Main where
+
+main :: IO ()
+main = putStrLn "Hello World 01!"

flake.lock

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+{
+  "nodes": {
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1634851050,
+        "narHash": "sha256-N83GlSGPJJdcqhUxSCS/WwW5pksYf3VP1M13cDRTSVA=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "c91f3de5adaf1de973b797ef7485e441a65b8935",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1635808042,
+        "narHash": "sha256-kQg7LzPj+UQlCAgD0dJhJ88QdzduXwIyqnTLXScKBbY=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "550dab224a26ec25e20e82c0c8bfc764e01b772e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

flake.nix

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+{
+  description = "Thorn's Haskell Repo";
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+  outputs = { self, ... }@inputs:
+  inputs.flake-utils.lib.eachSystem
+    [ "x86_64-linux" ]
+    (system:
+      let pkgs = import inputs.nixpkgs {
+        overlays = [ ((import ./overlay.nix) inputs) ];
+        inherit system;
+      };
+      in rec {
+        defaultPackage = packages.aoc2021;
+        packages = inputs.flake-utils.lib.flattenTree
+          ((import ./utils.nix) { inherit pkgs; inherit inputs; });
+        hydraJobs = builtins.listToAttrs
+        (map (s: { name = s; value = {
+            ${system} = packages.${s};
+          }; })
+          (builtins.attrNames packages));
+      }) // {
+        overlay = (import ./overlay.nix) inputs;
+      };
+}

overlay.nix

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+inputs: final: prev: {
+  haskellPackages = prev.haskellPackages.override {
+    overrides = haskellSelf: haskellSuper:
+      ((import ./utils.nix) { inherit inputs; pkgs = prev; })
+        // { };
+  };
+}

packages.nix

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+inputs: [
+  ./code
+]

utils.nix

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+{ inputs, pkgs, ... }:
+let
+  fn = root: map (p: "${root}/" + p) (builtins.attrNames (builtins.readDir root));
+  gn = root:
+    let items = builtins.readDir root;
+        fn = file: type:
+          if type == "regular"
+          then
+            (let m = (builtins.match "(.*)\\.cabal" file);
+            in if !(isNull m)
+            then { "${builtins.elemAt m 0}" = root; }
+            else {})
+          else {};
+    in builtins.foldl' (x: y: x // y) {} (builtins.attrValues (builtins.mapAttrs fn items));
+  hn = s:
+    builtins.filter
+      (x: (builtins.hasAttr "flake" x) && !x.flake)
+      s;
+  packagePaths = builtins.foldl'
+    (x: y: x // y)
+    {}
+    (map gn ((import ./packages.nix) inputs));
+in
+  builtins.mapAttrs
+    (name: path: pkgs.haskellPackages.callCabal2nix name path {})
+    packagePaths
+