From c0c9ab15d1f9edccabb61444b8114469ea3337b1 Mon Sep 17 00:00:00 2001
From: Jaculabilis <jaculabilis@git.alogoulogoi.com>
Date: Fri, 11 Feb 2022 23:44:40 -0800
Subject: [PATCH] Add dev shell configs

---
 README.md  | 35 +++++++++++++++++++++++++++++++++++
 flake.lock | 41 +++++++++++++++++++++++++++++++++++++++++
 flake.nix  | 18 +++++++++++-------
 3 files changed, 87 insertions(+), 7 deletions(-)
 create mode 100644 flake.lock

diff --git a/README.md b/README.md
index 370b41e..a5aca8a 100644
--- a/README.md
+++ b/README.md
@@ -30,4 +30,39 @@ $ git add flake.nix README.md
 $ git commit -m "Initial commit"
 $ git remote add origin gitea@git.alogoulogoi.com:Jaculabilis/5dplomacy.git
 $ git push -u origin master
+```
+
+We're doing this in .NET, so we need the .NET SDK. To do that, we're going to delcare a development environment in the flake config.
+
+```
+  inputs.flake-utils.url = "github:numtide/flake-utils";
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let pkgs = nixpkgs.legacyPackages.${system};
+      in rec {
+        devShell = pkgs.mkShell {
+          packages = [ pkgs.dotnet-sdk ];
+        };
+      }
+    );
+```
+
+Declaring `inputs.flake-utils` adds the `flake-utils` package as a dependency, which just gives us Nix helper functions. What's important here is that the `packages.x86_64-linux.hello` above has been abstracted away behind the `eachDefaultSystem` function: now we define our outputs with the `system` input as context, and flake-utils will define our outputs for each default system.
+
+Basically, stripping the boilerplate, we're just doing this:
+
+```
+rec {
+  devShell = pkgs.mkShell {
+    packages = [ pkgs.dotnet-sdk ];
+  };
+}
+```
+
+`pkgs.mkShell` is the derivation builder that creates shell environments. It takes `packages` as a list of input packages that will be made available in the shell environment it creates. We add `dotnet-sdk` to this, commit the changes to git, and enter our new shell with `nix develop`:
+
+```
+$ which dotnet
+/nix/store/87s452c8wj2zmy21q8q394f6rzf5y1br-dotnet-sdk-6.0.100/bin/dotnet
 ```
\ No newline at end of file
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 0000000..118806a
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,41 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "locked": {
+        "lastModified": 1644229661,
+        "narHash": "sha256-1YdnJAsNy69bpcjuoKdOYQX0YxZBiCYZo4Twxerqv7k=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "3cecb5b042f7f209c56ffd8371b2711a290ec797",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1644486793,
+        "narHash": "sha256-EeijR4guVHgVv+JpOX3cQO+1XdrkJfGmiJ9XVsVU530=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "1882c6b7368fd284ad01b0a5b5601ef136321292",
+        "type": "github"
+      },
+      "original": {
+        "id": "nixpkgs",
+        "type": "indirect"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
index 94f2327..2e569ff 100644
--- a/flake.nix
+++ b/flake.nix
@@ -1,11 +1,15 @@
 {
-  description = "A very basic flake";
+  description = "5D Diplomacy With Multiversal Time Travel";
 
-  outputs = { self, nixpkgs }: {
+  inputs.flake-utils.url = "github:numtide/flake-utils";
 
-    packages.x86_64-linux.hello = nixpkgs.legacyPackages.x86_64-linux.hello;
-
-    defaultPackage.x86_64-linux = self.packages.x86_64-linux.hello;
-
-  };
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let pkgs = nixpkgs.legacyPackages.${system};
+      in rec {
+        devShell = pkgs.mkShell {
+          packages = [ pkgs.dotnet-sdk ];
+        };
+      }
+    );
 }