diff --git a/README.md b/README.md
index 9cde15d..c4cf546 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,8 @@ Currently, following expressions are exported:
 | ----------------------- | ------------------------------------------------------------------------ |
 | `pkgs-sources.stable`   | Stable `nixpkgs` source (based on `release-22.05` `nixpkgs` branch)      |
 | `pkgs-sources.unstable` | Unstable `nixpkgs` source (based on `nixpkgs-unstable` `nixpkgs` branch) |
-| `tools.haskell`         | Various functions to make building Haskell development tools             |
+| `tools.devshell`        | Various functions for building a development shell                       |
+| `tools.haskell`         | Various functions for building Haskell development tools                 |
 
 ## License
 
diff --git a/default.nix b/default.nix
index d360428..20b05e4 100644
--- a/default.nix
+++ b/default.nix
@@ -14,6 +14,7 @@ in
 
   ## Categorized tools.
   tools = {
+    devshell = import ./tools/devshell { pkgs = import sources.nixpkgs { }; };
     haskell = import ./tools/haskell.nix;
   };
 }
diff --git a/nix/sources.json b/nix/sources.json
index b5e8573..aa2d84b 100644
--- a/nix/sources.json
+++ b/nix/sources.json
@@ -1,14 +1,14 @@
 {
     "nixpkgs": {
-        "branch": "release-22.05",
+        "branch": "release-22.11",
         "description": "Nix Packages collection",
         "homepage": "",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "82379884b2e9cf1ba65f5b14bbcb9d1438abb745",
-        "sha256": "0zh7h0hsbasl4d527zz7mr2msnffpf269si3jpw2sd62lk8zikz4",
+        "rev": "7300dca340ad08729891f843284bd385a1fac7fb",
+        "sha256": "1w25z6r71klrhv3bbqlg2pjlxpl6smkg84i32ij51840qhx5iq6c",
         "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/82379884b2e9cf1ba65f5b14bbcb9d1438abb745.tar.gz",
+        "url": "https://github.com/NixOS/nixpkgs/archive/7300dca340ad08729891f843284bd385a1fac7fb.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     },
     "nixpkgs-unstable": {
@@ -17,10 +17,10 @@
         "homepage": "",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "ff9793cfd1a25145a7e591af604675b3d6f68987",
-        "sha256": "087fgyq4q1nr44h52zz3q3h21i1svgip27fp5csa5mz6yzqkqakv",
+        "rev": "0c9aadc8eff6daaa5149d2df9e6c49baaf44161c",
+        "sha256": "0ya3v073pyb9bhw4ky362sk423ficygsr8ng7spmnmji1zmlpj40",
         "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/ff9793cfd1a25145a7e591af604675b3d6f68987.tar.gz",
+        "url": "https://github.com/NixOS/nixpkgs/archive/0c9aadc8eff6daaa5149d2df9e6c49baaf44161c.tar.gz",
         "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
     }
 }
diff --git a/tools/devshell/default.nix b/tools/devshell/default.nix
new file mode 100644
index 0000000..0390d86
--- /dev/null
+++ b/tools/devshell/default.nix
@@ -0,0 +1,6 @@
+{ pkgs, ... }:
+
+let
+  mkDevshell = import ./devsh.nix { pkgs = pkgs; };
+in
+mkDevshell
diff --git a/tools/devshell/devsh.nix b/tools/devshell/devsh.nix
new file mode 100644
index 0000000..bb9bc20
--- /dev/null
+++ b/tools/devshell/devsh.nix
@@ -0,0 +1,118 @@
+{ pkgs }:
+
+let
+  ## Create devsh script:
+  scriptDevsh = pkgs.writeScriptBin "devsh" (builtins.readFile ./devsh.py);
+
+  ## Example usage:
+  ##
+  ## ```
+  ## { compiler ? "ghc92" }:
+  ##
+  ## let
+  ##   ## Import this codebase's Nix helper set:
+  ##   nix = import ./nix { compiler = compiler; };
+  ##
+  ##   ## Get packages:
+  ##   pkgs = nix.pkgs;
+  ##
+  ##   ## Create the devshell:
+  ##   devshell = nix.telosnix.tools.devshell {
+  ##     name = "devshell-example";
+  ##     src = ./.;
+  ##     quickstart = ./README_quickstart.md;
+  ##     docs = [
+  ##       { name = "readme"; title = "Introduction"; path = "./README.md"; }
+  ##       { name = "quickstart"; title = "Quickstart"; path = "./README_quickstart.md"; }
+  ##       { name = "another-guide"; title = "Another Guide"; path = "./README_guide.ronn"; }
+  ##     ];
+  ##     extensions = {
+  ##       my-command = {
+  ##         help = "Help for my command";
+  ##         exec = "${my-command}/bin/my-command";
+  ##       };
+  ##     };
+  ##   };
+  ## in
+  ## pkgs.mkShell {
+  ##   buildInputs = [
+  ##     devshell
+  ##   ] ++ nix.haskell-dev-tools;
+  ##
+  ##   shellHook = ''
+  ##     devsh welcome
+  ##     echo
+  ##     devsh exec
+  ##
+  ##     ## Make sure that doctest finds correct GHC executable and libraries:
+  ##     export NIX_GHC=${nix.ghc}/bin/ghc
+  ##     export NIX_GHC_LIBDIR=${nix.ghc}/lib/${nix.ghc.meta.name}
+  ##   '';
+  ## }
+  ## ```
+  mkDevshell = { name, src, quickstart, docs ? [ ], extensions ? { } }:
+    with pkgs;
+    let
+      extensionDrvs = lib.attrsets.mapAttrs (name: value: writeShellScriptBin "devsh-extension-${name}" "${value.exec} \"\${@}\"") extensions;
+      extensionHelp = lib.strings.concatStrings (lib.attrsets.attrValues (lib.attrsets.mapAttrs (name: value: "${name}: ${value.help}\n") extensions));
+      extensionHelpFile = writeTextFile { name = "extensions.dat"; text = extensionHelp; };
+      binPathDevsh = lib.makeBinPath ([ figlet lolcat rich-cli ] ++ (lib.attrsets.attrValues extensionDrvs));
+    in
+    stdenv.mkDerivation {
+      name = name;
+      src = src;
+
+      nativeBuildInputs = [ makeWrapper ];
+
+      installPhase = ''
+        ## Create output directories:
+        mkdir -p $out/bin
+        mkdir -p $out/etc
+        mkdir -p $out/share/doc/guide/src
+        mkdir -p $out/share/doc/guide/html
+
+        ## Copy quickstart guide:
+        cp "${quickstart}" $out/share/doc/quickstart.md
+
+        ## Copy devshell extensions help:
+        cp "${extensionHelpFile}" $out/share/doc/extensions.dat
+
+        ## Copy the devshell guide sections:
+        ${toString (map ({name, title, path}: "cp \"${path}\" $out/share/doc/guide/src/${name}.md\n") docs)}
+
+        ## Write devshell guide index:
+        cat <<EOF > $out/share/doc/guide/src/SUMMARY.md
+        ${toString (map ({name, title, path}: "- [${title}](${name}.md)\n") docs)}
+        EOF
+
+        ## Write devshell guide configuration:
+        cat <<EOF > $out/share/doc/guide/book.toml
+        [book]
+        title = "${name}"
+        description = "This is the Development Shell Guide for ${name}."
+
+        [output.html]
+        default-theme = "light"
+        preferred-dark-theme = "ayu"
+        curly-quotes = true
+        mathjax-support = true
+        copy-fonts = true
+        EOF
+
+        ## Build devshell guide:
+        "${mdbook}/bin/mdbook" build --dest-dir $out/share/doc/guide/html $out/share/doc/guide
+
+        ## Copy scripts to the output destination:
+        cp ${scriptDevsh}/bin/devsh $out/bin/
+
+        ## Wrap devsh program:
+        wrapProgram $out/bin/devsh \
+          --prefix PATH : ${binPathDevsh} \
+          --set DEVSHELL_NAME "${name}" \
+          --set DEVSHELL_DOCS_DIR "$out/share/doc" \
+          --set DEVSHELL_QUICKSTART "$out/share/doc/quickstart.md" \
+          --set DEVSHELL_EXTENSIONS "$out/share/doc/extensions.dat"
+      '';
+    };
+in
+mkDevshell
diff --git a/tools/devshell/devsh.py b/tools/devshell/devsh.py
new file mode 100644
index 0000000..d4328a7
--- /dev/null
+++ b/tools/devshell/devsh.py
@@ -0,0 +1,94 @@
+#!/usr/bin/env python3
+
+# pyright: reportConstantRedefinition=false
+
+import argparse
+import os
+import subprocess as sp
+import sys
+from typing import Any
+
+DEVSHELL_NAME = os.environ["DEVSHELL_NAME"]
+DEVSHELL_DOCS_DIR = os.environ["DEVSHELL_DOCS_DIR"]
+DEVSHELL_QUICKSTART = os.environ["DEVSHELL_QUICKSTART"]
+DEVSHELL_EXTENSIONS = os.environ["DEVSHELL_EXTENSIONS"]
+DEVSHELL_EXTENSIONS_HELP = ""
+
+with open(DEVSHELL_EXTENSIONS) as cfile:
+    provided = cfile.read().strip()
+    if provided:
+        DEVSHELL_EXTENSIONS_HELP = f"""List of Extension Commands:
+===========================
+
+{provided}
+
+These extension commands can be executed as:
+
+devsh exec <command>
+"""
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(
+        description="devshell",
+        epilog=DEVSHELL_EXTENSIONS_HELP,
+        formatter_class=argparse.RawTextHelpFormatter,
+    )
+
+    subparsers = parser.add_subparsers()
+
+    subparser = subparsers.add_parser("banner", help="Print banner")
+    subparser.set_defaults(func=do_banner)
+
+    subparser = subparsers.add_parser("quickstart", help="Print quickstart guide")
+    subparser.set_defaults(func=do_quickstart)
+
+    subparser = subparsers.add_parser("welcome", help="Print welcome notice")
+    subparser.set_defaults(func=do_welcome)
+
+    subparser = subparsers.add_parser("guide", help="Open developer's guide")
+    subparser.set_defaults(func=do_guide)
+
+    subparser = subparsers.add_parser("exec", help="Execute an extension command")
+    subparser.add_argument(
+        "args",
+        nargs=argparse.REMAINDER,
+        help="Arguments to pass to the extension command",
+    )
+    subparser.set_defaults(func=do_exec)
+
+    args = parser.parse_args(args=None if sys.argv[1:] else ["--help"])
+    args.func(args)
+
+
+def do_banner(_args: Any) -> None:
+    ps = sp.Popen(("figlet", "-c", "-t", DEVSHELL_NAME), stdout=sp.PIPE)
+    sp.run(("lolcat", "-S", "20", "-p", "1", "-F", "0.02"), stdin=ps.stdout, check=True)
+    ps.wait()
+
+
+def do_quickstart(_args: Any) -> None:
+    sp.run(("rich", "-c", "-w", "80", DEVSHELL_QUICKSTART), check=True)
+
+
+def do_welcome(args: Any) -> None:
+    do_banner(args)
+    do_quickstart(args)
+
+
+def do_guide(_args: Any) -> None:
+    sp.run(("xdg-open", f"{DEVSHELL_DOCS_DIR}/guide/html/index.html"), check=True)
+
+
+def do_exec(args: Any) -> None:
+    if not args.args:
+        sys.stdout.write(DEVSHELL_EXTENSIONS_HELP)
+        return
+
+    args.args[0] = f"devsh-extension-{args.args[0]}"
+
+    sp.run(args.args, check=True, stdin=sys.stdin)
+
+
+if __name__ == "__main__":
+    main()
diff --git a/tools/haskell.nix b/tools/haskell.nix
index e7193e1..40cad61 100644
--- a/tools/haskell.nix
+++ b/tools/haskell.nix
@@ -18,9 +18,7 @@ let
   ## };
   overrideHaskellForDevTools =
     new: old: {
-      Cabal = old.Cabal_3_6_3_0;
-      fourmolu = old.fourmolu_0_8_2_0;
-      ghc-lib-parser = old.ghc-lib-parser_9_2_4_20220729;
+      ## Placeholder for overriding Haskell packages in case required.
     };
 
   ## Returns the Haskell set for development purposes.