diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 13c57c10..2792da70 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -24,26 +24,26 @@ jobs:
           ~/.cabal/packages
           ~/.cabal/store
           dist-newstyle
-        key: cabal-deps-${{ runner.os }}-${{ hashFiles('nix/sources.json') }}-${{ matrix.ghc-version }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('linear-base.cabal') }}-${{ github.sha }}
-        restore-keys: cabal-deps-${{ runner.os }}-${{ hashFiles('nix/sources.json') }}-${{ matrix.ghc-version }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('linear-base.cabal') }}-
+        key: cabal-deps-${{ runner.os }}-${{ hashFiles('flake.lock') }}-${{ matrix.ghc-version }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('linear-base.cabal') }}-${{ github.sha }}
+        restore-keys: cabal-deps-${{ runner.os }}-${{ hashFiles('flake.lock') }}-${{ matrix.ghc-version }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('linear-base.cabal') }}-
     - name: Build Nix dependencies
-      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "echo '=== Nix dependencies installed ==='"
+      run: nix develop .#devShells.x86_64-linux.ci-"${{ matrix.ghc-version }}" --command echo '=== Nix dependencies installed ==='
     - name: Init Cabal's config file
-      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal --config-file=/home/runner/.cabal/config user-config -f init"
+      run: nix develop .#devShells.x86_64-linux.ci-"${{ matrix.ghc-version }}" --command cabal --config-file=/home/runner/.cabal/config user-config -f init
     - name: Update Cabal's database
-      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal update"
+      run: nix develop .#devShells.x86_64-linux.ci-"${{ matrix.ghc-version }}" --command cabal update
     - name: Build Cabal's dependencies
-      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal build --dependencies-only"
+      run: nix develop .#devShells.x86_64-linux.ci-"${{ matrix.ghc-version }}" --command cabal build --dependencies-only
     - name: Build
-      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal build"
+      run: nix develop .#devShells.x86_64-linux.ci-"${{ matrix.ghc-version }}" --command cabal build
     - name: Haddock
-      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal haddock"
+      run: nix develop .#devShells.x86_64-linux.ci-"${{ matrix.ghc-version }}" --command cabal haddock
     - name: cabal-docspec
-      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal-docspec"
+      run: nix develop .#devShells.x86_64-linux.ci-"${{ matrix.ghc-version }}" --command cabal-docspec
     - name: Build benchmarks
-      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal build linear-base:bench:bench"
+      run: nix develop .#devShells.x86_64-linux.ci-"${{ matrix.ghc-version }}" --command cabal build linear-base:bench:bench
     - name: Run benchmarks
-      run: nix-shell --arg ghcVersion '"${{ matrix.ghc-version }}"' --arg installHls 'false' --pure --run "cabal bench 2>&1 | tee benchmark_ghc${{ matrix.ghc-version }}.txt"
+      run: nix develop .#devShells.x86_64-linux.ci-"${{ matrix.ghc-version }}" --command cabal bench 2>&1 | tee benchmark_ghc${{ matrix.ghc-version }}.txt
     - name: Upload benchmark results
       uses: actions/upload-artifact@v4
       with:
@@ -60,16 +60,10 @@ jobs:
     - uses: cachix/install-nix-action@v15
       with:
         nix_path: "${{ env.nixpkgs-url }}"
-    - name: Cache Stack dependencies
-      uses: actions/cache@v4
-      with:
-        path: ~/.stack
-        key: stack-deps-ormolu-${{ runner.os }}-${{ hashFiles('nix/sources.json') }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('stack.yaml.lock') }}-${{ github.sha }}
-        restore-keys: stack-deps-ormolu-${{ runner.os }}-${{ hashFiles('nix/sources.json') }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('stack.yaml.lock') }}-
     - name: Build Nix dependencies
-      run: nix-shell --arg installHls 'false' --pure --run "echo '=== Nix dependencies installed ==='"
+      run: nix develop .#devShells.x86_64-linux.ci-stack --command echo '=== Nix dependencies installed ==='
     - name: check formatting
-      run: nix-shell --arg installHls 'false' --pure --run 'stack build ormolu && stack exec ormolu -- -m check $(find . -type f -name "*.hs-boot" -o -name "*.hs")'
+      run: nix develop .#devShells.x86_64-linux.ci-stack --command ormolu -m check $(find . -type f -name "*.hs-boot" -o -name "*.hs")
 
   stack-build:
     name: stack build
@@ -83,9 +77,9 @@ jobs:
       uses: actions/cache@v4
       with:
         path: ~/.stack
-        key: stack-deps-${{ runner.os }}-${{ hashFiles('nix/sources.json') }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('stack.yaml.lock', 'linear-base.cabal') }}-${{ github.sha }}
-        restore-keys: stack-deps-${{ runner.os }}-${{ hashFiles('nix/sources.json') }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('stack.yaml.lock', 'linear-base.cabal') }}-
+        key: stack-deps-${{ runner.os }}-${{ hashFiles('flake.lock') }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('stack.yaml.lock', 'linear-base.cabal') }}-${{ github.sha }}
+        restore-keys: stack-deps-${{ runner.os }}-${{ hashFiles('flake.lock') }}-v${{ env.cache-invalidation-key }}-${{ hashFiles('stack.yaml.lock', 'linear-base.cabal') }}-
     - name: Build Nix dependencies
-      run: nix-shell --arg installHls 'false' --pure --run "echo '=== Nix dependencies installed ==='"
+      run: nix develop .#devShells.x86_64-linux.ci-stack --command echo '=== Nix dependencies installed ==='
     - name: Build
-      run: nix-shell --arg installHls 'false' --pure --run "stack build --pedantic --test --bench --no-run-benchmarks"
+      run: nix develop .#devShells.x86_64-linux.ci-stack --command stack build --pedantic --test --bench --no-run-benchmarks
diff --git a/bench/Data/Mutable/HashMap.hs b/bench/Data/Mutable/HashMap.hs
index b3e914b4..321dde15 100644
--- a/bench/Data/Mutable/HashMap.hs
+++ b/bench/Data/Mutable/HashMap.hs
@@ -22,7 +22,7 @@ import qualified Data.HashMap.Strict as Map
 import qualified Data.HashTable.ST.Basic as BasicST
 import qualified Data.HashTable.ST.Cuckoo as CuckooST
 import Data.Hashable (Hashable (..), hashWithSalt)
-import Data.List (foldl')
+import qualified Data.List as List
 import qualified Data.Unrestricted.Linear as Linear
 import GHC.Generics (Generic)
 import qualified Prelude.Linear as Linear
@@ -199,7 +199,7 @@ vanilla_hashmap_strict inp@(BenchInput {pairs = kvs}) =
       bench (descriptions !! n) $ nf (\xs -> f xs Map.empty) kvs
 
     foldlx :: (b -> a -> b) -> [a] -> b -> b
-    foldlx f xs b = foldl' f b xs
+    foldlx f xs b = List.foldl' f b xs
 
     look :: Map.HashMap Key Int -> Key -> Map.HashMap Key Int
     look m k = case m Map.!? k of
@@ -208,7 +208,7 @@ vanilla_hashmap_strict inp@(BenchInput {pairs = kvs}) =
 
     bench1 :: Benchmark
     bench1 = mkBench 0 $
-      \xs hm -> foldl' (\m (k, v) -> Map.delete k (Map.insert k v m)) hm xs
+      \xs hm -> List.foldl' (\m (k, v) -> Map.delete k (Map.insert k v m)) hm xs
 
     bench2 :: Benchmark
     bench2 = mkBench 1 $
diff --git a/cabal.project b/cabal.project
index f416fef5..35c833a6 100644
--- a/cabal.project
+++ b/cabal.project
@@ -3,4 +3,4 @@ packages: *.cabal
 tests: True
 benchmarks: True
 allow-newer: all
-index-state: 2024-09-13T13:31:57Z
+index-state: 2026-05-12T09:26:21Z
diff --git a/flake.lock b/flake.lock
new file mode 100644
index 00000000..e9e04e40
--- /dev/null
+++ b/flake.lock
@@ -0,0 +1,61 @@
+{
+  "nodes": {
+    "flake-utils": {
+      "inputs": {
+        "systems": "systems"
+      },
+      "locked": {
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "numtide",
+        "repo": "flake-utils",
+        "type": "github"
+      }
+    },
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1778458615,
+        "narHash": "sha256-cY07EsdhBJ8tFXPzDYevgqxRev9ZLxFonuq9wmq5kwg=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "c6e5ca3c836a5f4dd9af9f2c1fc1c38f0fac988a",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixpkgs-unstable",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "flake-utils": "flake-utils",
+        "nixpkgs": "nixpkgs"
+      }
+    },
+    "systems": {
+      "locked": {
+        "lastModified": 1681028828,
+        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
+        "owner": "nix-systems",
+        "repo": "default",
+        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "nix-systems",
+        "repo": "default",
+        "type": "github"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}
diff --git a/flake.nix b/flake.nix
new file mode 100644
index 00000000..5a39915d
--- /dev/null
+++ b/flake.nix
@@ -0,0 +1,86 @@
+{
+  description = "Linear-base";
+
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+  inputs.flake-utils.url = "github:numtide/flake-utils";
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = import nixpkgs { inherit system; inherit overlays; };
+
+        # need to match Stackage LTS version from stack.yaml snapshot
+        stack-ghc-version = "ghc9103";
+
+        # Versions used by CI's Cabal-based matrix
+        ci-ghc-versions = ["96" "98" "910" "912"];
+
+        cabal-docspec = import ./nix/cabal-docspec.nix { inherit pkgs; };
+
+        buildTools = ghc-ver:
+          let hask = pkgs.haskell.packages."${ghc-ver}"; in
+          [
+            hask.ghc
+            pkgs.cabal-install
+            stack-wrapped
+            cabal-docspec
+            pkgs.ormolu # Haskell formatter
+          ];
+
+        devTools = ghc-ver:
+          let hask = pkgs.haskell.packages."${ghc-ver}"; in
+          [
+            hask.ghcid # Continuous terminal Haskell compile checker
+            hask.haskell-language-server # LSP server for editor
+          ];
+
+        mkCIShellFor = ghc-ver: pkgs.mkShell {
+          # Set UTF-8 local so that run-tests can parse GHC's unicode output.
+          LANG="C.UTF-8";
+
+          buildInputs = buildTools "${ghc-ver}";
+        };
+
+        ci-shells = builtins.listToAttrs (map (ver:
+          { name = "ci-${ver}"; value = mkCIShellFor "ghc${ver}"; }
+          ) ci-ghc-versions);
+
+        mkDevShellFor = ghc-ver: pkgs.mkShell {
+          # Set UTF-8 local so that run-tests can parse GHC's unicode output.
+          LANG="C.UTF-8";
+
+          buildInputs = buildTools "${ghc-ver}" ++ devTools "${ghc-ver}";
+
+        };
+
+        cabal-dev-shells = builtins.listToAttrs (map (ver:
+          { name = "dev-${ver}"; value = mkDevShellFor "ghc${ver}"; }
+          ) ci-ghc-versions);
+
+        # See https://docs.haskellstack.org/en/stable/topics/nix_integration/
+        stack-wrapped = pkgs.symlinkJoin {
+          name = "stack"; # will be available as the usual `stack` in terminal
+          paths = [ pkgs.stack ];
+          buildInputs = [ pkgs.makeWrapper ];
+          postBuild = ''
+            wrapProgram $out/bin/stack \
+              --add-flags "\
+                --no-nix \
+                --system-ghc \
+                --no-install-ghc \
+              "
+          '';
+        };
+
+        overlays = [
+        ];
+
+      in {
+
+        devShells = ci-shells // cabal-dev-shells // {
+          default = mkDevShellFor stack-ghc-version;
+
+          ci-stack = mkCIShellFor stack-ghc-version;};
+      }
+    );
+}
diff --git a/format.sh b/format.sh
index 24538b65..0203b267 100755
--- a/format.sh
+++ b/format.sh
@@ -1,14 +1,10 @@
 #!/usr/bin/env bash
-# Format linear-base using the version of Ormolu specified in stack.yaml.
+# Format linear-base using the version of Ormolu from the PATH. It's recommended
+# using the version provided by `flake.nix`, since it's the one used by the CI
+# to enforce formatting.
 
 set -e
 
 export LANG="C.UTF-8"
 
-stack build ormolu
-## We can't format cabal at the moment because `cabal format` inlines
-## common stanzas, which is very much something that we don't want. See
-## https://github.com/haskell/cabal/issues/5734
-#
-# cabal format
-stack exec ormolu -- -m inplace $(find . -type f -name "*.hs-boot" -o -name "*.hs")
+ormolu -m inplace $(find . -type f -name "*.hs-boot" -o -name "*.hs")
diff --git a/nix/shell-stack.nix b/nix/shell-stack.nix
deleted file mode 100644
index 109e10d6..00000000
--- a/nix/shell-stack.nix
+++ /dev/null
@@ -1,9 +0,0 @@
-# Provide Nix support to Stack by expressing system packages required, rather than manually having to install stuff like Zlib
-# Inspired by https://docs.haskellstack.org/en/stable/nix_integration/#using-a-custom-shellnix-file
-{ ghc, system ? builtins.currentSystem, sources ? import ./sources.nix, pkgs ? import sources.nixpkgs { inherit system; } }:
-
-pkgs.haskell.lib.buildStackProject {
-  inherit ghc;
-  name = "linear-base";
-  buildInputs = [ ];
-}
diff --git a/nix/sources.json b/nix/sources.json
deleted file mode 100644
index 087becc5..00000000
--- a/nix/sources.json
+++ /dev/null
@@ -1,26 +0,0 @@
-{
-    "niv": {
-        "branch": "master",
-        "description": "Easy dependency management for Nix projects",
-        "homepage": "https://github.com/nmattia/niv",
-        "owner": "nmattia",
-        "repo": "niv",
-        "rev": "dd678782cae74508d6b4824580d2b0935308011e",
-        "sha256": "0dk8dhh9vla2s409anmrfkva6h3r32xmz3cm8ha09wyk8iyf1f87",
-        "type": "tarball",
-        "url": "https://github.com/nmattia/niv/archive/dd678782cae74508d6b4824580d2b0935308011e.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    },
-    "nixpkgs": {
-        "branch": "master",
-        "description": "Nix Packages collection",
-        "homepage": "https://github.com/NixOS/nixpkgs",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "0c501072d51fca9fc0f9fd123e106ad2f89c6b09",
-        "sha256": "0xmhs479g1gzqv320zlmx44wzqlnb741kp6zwj1m3nzzdv94v472",
-        "type": "tarball",
-        "url": "https://github.com/NixOS/nixpkgs/archive/0c501072d51fca9fc0f9fd123e106ad2f89c6b09.tar.gz",
-        "url_template": "https://github.com/<owner>/<repo>/archive/<rev>.tar.gz"
-    }
-}
diff --git a/nix/sources.nix b/nix/sources.nix
deleted file mode 100644
index fe3dadf7..00000000
--- a/nix/sources.nix
+++ /dev/null
@@ -1,198 +0,0 @@
-# This file has been generated by Niv.
-
-let
-
-  #
-  # The fetchers. fetch_<type> fetches specs of type <type>.
-  #
-
-  fetch_file = pkgs: name: spec:
-    let
-      name' = sanitizeName name + "-src";
-    in
-    if spec.builtin or true then
-      builtins_fetchurl { inherit (spec) url sha256; name = name'; }
-    else
-      pkgs.fetchurl { inherit (spec) url sha256; name = name'; };
-
-  fetch_tarball = pkgs: name: spec:
-    let
-      name' = sanitizeName name + "-src";
-    in
-    if spec.builtin or true then
-      builtins_fetchTarball { name = name'; inherit (spec) url sha256; }
-    else
-      pkgs.fetchzip { name = name'; inherit (spec) url sha256; };
-
-  fetch_git = name: spec:
-    let
-      ref =
-        spec.ref or (
-          if spec ? branch then "refs/heads/${spec.branch}" else
-          if spec ? tag then "refs/tags/${spec.tag}" else
-          abort "In git source '${name}': Please specify `ref`, `tag` or `branch`!"
-        );
-      submodules = spec.submodules or false;
-      submoduleArg =
-        let
-          nixSupportsSubmodules = builtins.compareVersions builtins.nixVersion "2.4" >= 0;
-          emptyArgWithWarning =
-            if submodules
-            then
-              builtins.trace
-                (
-                  "The niv input \"${name}\" uses submodules "
-                  + "but your nix's (${builtins.nixVersion}) builtins.fetchGit "
-                  + "does not support them"
-                )
-                { }
-            else { };
-        in
-        if nixSupportsSubmodules
-        then { inherit submodules; }
-        else emptyArgWithWarning;
-    in
-    builtins.fetchGit
-      ({ url = spec.repo; inherit (spec) rev; inherit ref; } // submoduleArg);
-
-  fetch_local = spec: spec.path;
-
-  fetch_builtin-tarball = name: throw
-    ''[${name}] The niv type "builtin-tarball" is deprecated. You should instead use `builtin = true`.
-        $ niv modify ${name} -a type=tarball -a builtin=true'';
-
-  fetch_builtin-url = name: throw
-    ''[${name}] The niv type "builtin-url" will soon be deprecated. You should instead use `builtin = true`.
-        $ niv modify ${name} -a type=file -a builtin=true'';
-
-  #
-  # Various helpers
-  #
-
-  # https://github.com/NixOS/nixpkgs/pull/83241/files#diff-c6f540a4f3bfa4b0e8b6bafd4cd54e8bR695
-  sanitizeName = name:
-    (
-      concatMapStrings (s: if builtins.isList s then "-" else s)
-        (
-          builtins.split "[^[:alnum:]+._?=-]+"
-            ((x: builtins.elemAt (builtins.match "\\.*(.*)" x) 0) name)
-        )
-    );
-
-  # The set of packages used when specs are fetched using non-builtins.
-  mkPkgs = sources: system:
-    let
-      sourcesNixpkgs =
-        import (builtins_fetchTarball { inherit (sources.nixpkgs) url sha256; }) { inherit system; };
-      hasNixpkgsPath = builtins.any (x: x.prefix == "nixpkgs") builtins.nixPath;
-      hasThisAsNixpkgsPath = <nixpkgs> == ./.;
-    in
-    if builtins.hasAttr "nixpkgs" sources
-    then sourcesNixpkgs
-    else if hasNixpkgsPath && ! hasThisAsNixpkgsPath then
-      import <nixpkgs> { }
-    else
-      abort
-        ''
-          Please specify either <nixpkgs> (through -I or NIX_PATH=nixpkgs=...) or
-          add a package called "nixpkgs" to your sources.json.
-        '';
-
-  # The actual fetching function.
-  fetch = pkgs: name: spec:
-
-    if ! builtins.hasAttr "type" spec then
-      abort "ERROR: niv spec ${name} does not have a 'type' attribute"
-    else if spec.type == "file" then fetch_file pkgs name spec
-    else if spec.type == "tarball" then fetch_tarball pkgs name spec
-    else if spec.type == "git" then fetch_git name spec
-    else if spec.type == "local" then fetch_local spec
-    else if spec.type == "builtin-tarball" then fetch_builtin-tarball name
-    else if spec.type == "builtin-url" then fetch_builtin-url name
-    else
-      abort "ERROR: niv spec ${name} has unknown type ${builtins.toJSON spec.type}";
-
-  # If the environment variable NIV_OVERRIDE_${name} is set, then use
-  # the path directly as opposed to the fetched source.
-  replace = name: drv:
-    let
-      saneName = stringAsChars (c: if (builtins.match "[a-zA-Z0-9]" c) == null then "_" else c) name;
-      ersatz = builtins.getEnv "NIV_OVERRIDE_${saneName}";
-    in
-    if ersatz == "" then drv else
-      # this turns the string into an actual Nix path (for both absolute and
-      # relative paths)
-    if builtins.substring 0 1 ersatz == "/" then /. + ersatz else /. + builtins.getEnv "PWD" + "/${ersatz}";
-
-  # Ports of functions for older nix versions
-
-  # a Nix version of mapAttrs if the built-in doesn't exist
-  mapAttrs = builtins.mapAttrs or (
-    f: set: with builtins;
-    listToAttrs (map (attr: { name = attr; value = f attr set.${attr}; }) (attrNames set))
-  );
-
-  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/lists.nix#L295
-  range = first: last: if first > last then [ ] else builtins.genList (n: first + n) (last - first + 1);
-
-  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L257
-  stringToCharacters = s: map (p: builtins.substring p 1 s) (range 0 (builtins.stringLength s - 1));
-
-  # https://github.com/NixOS/nixpkgs/blob/0258808f5744ca980b9a1f24fe0b1e6f0fecee9c/lib/strings.nix#L269
-  stringAsChars = f: s: concatStrings (map f (stringToCharacters s));
-  concatMapStrings = f: list: concatStrings (map f list);
-  concatStrings = builtins.concatStringsSep "";
-
-  # https://github.com/NixOS/nixpkgs/blob/8a9f58a375c401b96da862d969f66429def1d118/lib/attrsets.nix#L331
-  optionalAttrs = cond: as: if cond then as else { };
-
-  # fetchTarball version that is compatible between all the versions of Nix
-  builtins_fetchTarball = { url, name ? null, sha256 }@attrs:
-    let
-      inherit (builtins) lessThan nixVersion fetchTarball;
-    in
-    if lessThan nixVersion "1.12" then
-      fetchTarball ({ inherit url; } // (optionalAttrs (name != null) { inherit name; }))
-    else
-      fetchTarball attrs;
-
-  # fetchurl version that is compatible between all the versions of Nix
-  builtins_fetchurl = { url, name ? null, sha256 }@attrs:
-    let
-      inherit (builtins) lessThan nixVersion fetchurl;
-    in
-    if lessThan nixVersion "1.12" then
-      fetchurl ({ inherit url; } // (optionalAttrs (name != null) { inherit name; }))
-    else
-      fetchurl attrs;
-
-  # Create the final "sources" from the config
-  mkSources = config:
-    mapAttrs
-      (
-        name: spec:
-          if builtins.hasAttr "outPath" spec
-          then
-            abort
-              "The values in sources.json should not have an 'outPath' attribute"
-          else
-            spec // { outPath = replace name (fetch config.pkgs name spec); }
-      )
-      config.sources;
-
-  # The "config" used by the fetchers
-  mkConfig =
-    { sourcesFile ? if builtins.pathExists ./sources.json then ./sources.json else null
-    , sources ? if sourcesFile == null then { } else builtins.fromJSON (builtins.readFile sourcesFile)
-    , system ? builtins.currentSystem
-    , pkgs ? mkPkgs sources system
-    }: rec {
-      # The sources, i.e. the attribute set of spec name to spec
-      inherit sources;
-
-      # The "pkgs" (evaluated nixpkgs) to use for e.g. non-builtin fetchers
-      inherit pkgs;
-    };
-
-in
-mkSources (mkConfig { }) // { __functor = _: settings: mkSources (mkConfig settings); }
diff --git a/shell.nix b/shell.nix
deleted file mode 100644
index e703f76f..00000000
--- a/shell.nix
+++ /dev/null
@@ -1,36 +0,0 @@
-{ system ? builtins.currentSystem, sources ? import ./nix/sources.nix, ghcVersion ? "96", installHls ? true }:
-
-let
-  selectHls = self: super: {
-    haskell-language-server = super.haskell-language-server.override { supportedGhcVersions = [ "${ghcVersion}" ]; };
-  };
-  pkgs = import sources.nixpkgs { inherit system; overlays = [ selectHls ]; };
-  cabal-docspec = import ./nix/cabal-docspec.nix { inherit pkgs; };
-  stack-wrapped = pkgs.symlinkJoin {
-    name = "stack";
-    paths = [ pkgs.stack ];
-    buildInputs = [ pkgs.makeWrapper ];
-    postBuild = ''
-      wrapProgram $out/bin/stack \
-        --add-flags "\
-          --nix \
-          --nix-path=\\"nixpkgs=${pkgs.path}\\"
-          --nix-shell-file nix/shell-stack.nix \
-        "
-    '';
-  };
-in with pkgs;
-
-mkShell {
-  # Set UTF-8 local so that run-tests can parse GHC's unicode output.
-  LANG="C.UTF-8";
-  NIX_PATH = "nixpkgs=${pkgs.path}";
-
-  buildInputs = [
-    haskell.compiler."ghc${ghcVersion}"
-    cabal-install
-    stack-wrapped
-    nix
-    cabal-docspec
-  ] ++ (if installHls then [ haskell-language-server ] else []);
-}
diff --git a/stack.yaml b/stack.yaml
index 790b9413..af03a6da 100644
--- a/stack.yaml
+++ b/stack.yaml
@@ -1,4 +1,4 @@
-resolver: lts-22.34
+resolver: lts-24.40
 packages:
 - '.'
 extra-deps:
diff --git a/stack.yaml.lock b/stack.yaml.lock
index 401a580e..a5d75184 100644
--- a/stack.yaml.lock
+++ b/stack.yaml.lock
@@ -1,12 +1,12 @@
 # This file was autogenerated by Stack.
 # You should not edit this file by hand.
 # For more information, please see the documentation at:
-#   https://docs.haskellstack.org/en/stable/lock_files
+#   https://docs.haskellstack.org/en/stable/topics/lock_files
 
 packages: []
 snapshots:
 - completed:
-    sha256: edbd50d7e7c85c13ad5f5835ae2db92fab1e9cf05ecf85340e2622ec0a303df1
-    size: 720020
-    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/22/34.yaml
-  original: lts-22.34
+    sha256: 514c8048a143da1e6f2c18484467d2136033a0b94b6617fe333089817edbbc27
+    size: 729000
+    url: https://raw.githubusercontent.com/commercialhaskell/stackage-snapshots/master/lts/24/40.yaml
+  original: lts-24.40
diff --git a/test/Test/Data/List.hs b/test/Test/Data/List.hs
index a9d6f2d0..528e680c 100644
--- a/test/Test/Data/List.hs
+++ b/test/Test/Data/List.hs
@@ -1,5 +1,6 @@
 {-# LANGUAGE OverloadedStrings #-}
 {-# LANGUAGE NoImplicitPrelude #-}
+{-# OPTIONS_GHC -Wno-x-partial #-}
 
 module Test.Data.List (listTests) where