fix: update nix shell to work with current bounds, add flake

cabal.project

@@ -70,6 +70,9 @@ if(impl(ghc >= 9.6.1))
   package servant-server
     ghc-options: -fprint-redundant-promotion-ticks
 
+  package lzma
+    flags: -pkgconfig
+
 -- This block is for GHC 9.10.1.
 allow-newer: servant-openapi3:base
 allow-newer: openapi3:base

default.nix

@@ -4,7 +4,7 @@ with (builtins.fromJSON (builtins.readFile ./nix/nixpkgs.json));
     url = "https://github.com/NixOS/nixpkgs/archive/${rev}.tar.gz";
     inherit sha256;
   }) {}
-, compiler ? "ghc883"
+, compiler ? "ghc92"
 }:
 let
   overrides = self: super: {

flake.nix

@@ -0,0 +1,45 @@
+{
+  description = "Servant development environment";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-24.05-darwin";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs { inherit system; };
+
+        mkDevShell = { compiler ? "ghc92", tutorial ? false }:
+          let
+            ghc = pkgs.haskell.packages.${compiler}.ghcWithPackages (_: []);
+            docstuffs = pkgs.python3.withPackages (ps: with ps; [ recommonmark sphinx sphinx_rtd_theme ]);
+          in
+          pkgs.mkShell {
+            buildInputs = with pkgs; [
+              ghc
+              zlib
+              python3
+              wget
+              cabal-install
+              postgresql
+              openssl
+              stack
+              haskellPackages.hspec-discover
+            ] ++ (if tutorial then [docstuffs postgresql] else []);
+
+            shellHook = ''
+              eval $(grep export ${ghc}/bin/ghc)
+              export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:"${pkgs.zlib}/lib";
+            '';
+          };
+      in
+      {
+        devShells = {
+          default = mkDevShell {};
+          tutorial = mkDevShell { tutorial = true; };
+        };
+      }
+    );
+}

nix/README.md

@@ -22,11 +22,21 @@ a particular ghc version, e.g:
 $ nix-shell nix/shell.nix --argstr compiler ghcHEAD
 ```
 
-**Possible GHC versions**
--   `ghc865Binary`
--   `ghc884`
--   `ghc8104` - default
--   `ghc901`
+The default is `ghc92`.
+
+To check which which ghc compiler options are available:
+
+```sh
+$ nix-env -f nix/nixpkgs.nix -qaP -A haskell.compiler
+```
+
+If you prefer to use flakes, the `flake.nix` file provides an
+equivalent default devShell to `shell.nix`. In addition, the
+tutorial is provided as a separate flake output:
+
+```sh
+$ nix develop .#tutorial
+```
 
 ### Cabal users
 
@@ -38,4 +48,4 @@ GHC version can be chosen via the nix-shell parameter
 
 Since the ghc version is set by the LTS version, it is preferable to use the `ghc8104` version parameter for the nix-shell.
 
-`stack --no-nix --system-ghc <command>`
+`stack --no-nix --system-ghc <command>`

nix/nixpkgs.json

@@ -1,4 +1,4 @@
 {
-  "rev" : "05f0934825c2a0750d4888c4735f9420c906b388",
-  "sha256" : "1g8c2w0661qn89ajp44znmwfmghbbiygvdzq0rzlvlpdiz28v6gy"
+  "rev" : "63dacb46bf939521bdc93981b4cbb7ecb58427a0",
+  "sha256" : "1lr1h35prqkd1mkmzriwlpvxcb34kmhc9dnr48gkm8hh089hifmx"
 }

nix/nixpkgs.nix

@@ -1,4 +1,4 @@
 import (builtins.fetchTarball {
-  url = "https://github.com/NixOS/nixpkgs/archive/refs/tags/21.05.tar.gz";
-  sha256 = "sha256:1ckzhh24mgz6jd1xhfgx0i9mijk6xjqxwsshnvq789xsavrmsc36";
+  url = "https://github.com/NixOS/nixpkgs/archive/refs/tags/24.05.tar.gz";
+  sha256 = "sha256:1lr1h35prqkd1mkmzriwlpvxcb34kmhc9dnr48gkm8hh089hifmx";
 }) {}

nix/shell.nix

@@ -1,8 +1,8 @@
-{ compiler ? "ghc8104"
+{ compiler ? "ghc92"
 , tutorial ? false
 , pkgs ? import ./nixpkgs.nix
 }:
-  
+
   with pkgs;
 
   let