add flake-compat to flake.nix and use sha256 in default.nix

default.nix

@@ -1,3 +1,10 @@
-(import (fetchTarball "https://github.com/edolstra/flake-compat/archive/master.tar.gz") {
-  src = ./.;
-}).defaultNix
+(import
+  (
+    let lock = builtins.fromJSON (builtins.readFile ./flake.lock); in
+    fetchTarball {
+      url = "https://github.com/edolstra/flake-compat/archive/${lock.nodes.flake-compat.locked.rev}.tar.gz";
+      sha256 = lock.nodes.flake-compat.locked.narHash;
+    }
+  )
+  { src = ./.; }
+).defaultNix

flake.lock

@@ -1,5 +1,21 @@
 {
   "nodes": {
+    "flake-compat": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1673956053,
+        "narHash": "sha256-4gtG9iQuiKITOjNQQeQIpoIB6b16fm+504Ch3sNKLd8=",
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "rev": "35bb57c0c8d8b62bbfd284272c928ceb64ddbde9",
+        "type": "github"
+      },
+      "original": {
+        "owner": "edolstra",
+        "repo": "flake-compat",
+        "type": "github"
+      }
+    },
     "lowdown-src": {
       "flake": false,
       "locked": {
@@ -50,6 +66,7 @@
     },
     "root": {
       "inputs": {
+        "flake-compat": "flake-compat",
         "lowdown-src": "lowdown-src",
         "nixpkgs": "nixpkgs",
         "nixpkgs-regression": "nixpkgs-regression"

flake.nix

@@ -4,8 +4,9 @@
   inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-22.11-small";
   inputs.nixpkgs-regression.url = "github:NixOS/nixpkgs/215d4d0fd80ca5163643b03a33fde804a29cc1e2";
   inputs.lowdown-src = { url = "github:kristapsdz/lowdown"; flake = false; };
+  inputs.flake-compat = { url = "github:edolstra/flake-compat"; flake = false; };
 
-  outputs = { self, nixpkgs, nixpkgs-regression, lowdown-src }:
+  outputs = { self, nixpkgs, nixpkgs-regression, lowdown-src, flake-compat }:
 
     let
       inherit (nixpkgs) lib;