diff --git a/.eslintrc.json b/.eslintrc.json
deleted file mode 100644
index 1c6afb9..0000000
--- a/.eslintrc.json
+++ /dev/null
@@ -1,26 +0,0 @@
-{
-  "parserOptions": {
-    "ecmaVersion": 6,
-    "sourceType": "module"
-  },
-  "extends": "eslint:recommended",
-  "rules": {
-    "strict": [2, "global"],
-    "block-scoped-var": 2,
-    "consistent-return": 2,
-    "eqeqeq": [2, "smart"],
-    "guard-for-in": 2,
-    "no-caller": 2,
-    "no-extend-native": 2,
-    "no-loop-func": 2,
-    "no-new": 2,
-    "no-param-reassign": 2,
-    "no-return-assign": 2,
-    "no-unused-expressions": 2,
-    "no-use-before-define": 2,
-    "radix": [2, "always"],
-    "indent": [2, 2],
-    "quotes": [2, "double"],
-    "semi": [2, "always"]
-  }
-}
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c69237a..d624d2e 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -4,32 +4,24 @@ on:
   push:
     branches: [master]
   pull_request:
-    branches: [master]
 
 jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-
-      - uses: purescript-contrib/setup-purescript@main
-        with:
-          purescript: "unstable"
+      - uses: actions/checkout@v4
 
-      - uses: actions/setup-node@v2
+      - uses: cachix/install-nix-action@v27
         with:
-          node-version: "14.x"
+          extra_nix_config: |
+            extra-substituters = https://cache.iog.io https://purescript-lua.cachix.org
+            extra-trusted-public-keys = hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= purescript-lua.cachix.org-1:yLs4ei2HtnuPtzLekOrW3xdfm95+Etw15gwgyIGTayA=
 
-      - name: Install dependencies
-        run: |
-          npm install -g bower
-          npm install
-          bower install --production
+      - name: Build
+        run: nix develop -c ./scripts/build
 
-      - name: Build source
-        run: npm run-script build
+      - name: Test
+        run: if [ -f scripts/test ]; then nix develop -c bash ./scripts/test; fi
 
-      - name: Run tests
-        run: |
-          bower install
-          npm run-script test --if-present
+      - name: Luacheck
+        run: nix develop -c luacheck --quiet --std lua51 --no-unused-args src/
diff --git a/.gitignore b/.gitignore
index 7bb9d6d..db67e9a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,9 +1,4 @@
 /.*
 !/.gitignore
-!/.github
-!/.eslintrc.json
-!/.travis.yml
-package-lock.json
-/bower_components/
-/node_modules/
+!/.github/
 /output/
diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000..12c3f5f
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,41 @@
+# AGENTS.md
+
+A PureScript→Lua FFI fork in the [`purescript-lua`](https://github.com/purescript-lua/purescript-lua) package set. Generated code targets **Lua 5.1**.
+
+## Commands
+
+All commands run inside the nix dev shell:
+
+- Build: `nix develop -c ./scripts/build`
+- Test: `nix develop -c bash ./scripts/test` (only forks that ship Lua regression tests have one)
+- Lint: `nix develop -c luacheck --quiet --std lua51 --no-unused-args src/`
+
+## Lua 5.1 target
+
+The output runs on Lua 5.1, which is stricter than 5.3:
+
+- No `table.unpack`, `bit32`, `utf8`, or the `//` operator. `math.pow` and `math.atan2` do exist.
+- Array-style tables are 1-indexed: the first element is `t[1]`, not `t[0]`.
+- `unit` is `{}`, never `nil`: a `nil` table element silently disappears, which would collapse `Array Unit` into an empty table.
+- Lua 5.1 mangles some Lua 5.3 string escapes, so keep FFI string escapes 5.1-safe.
+
+## FFI files (`src/*.lua`)
+
+pslua's foreign-file parser needs every exported value wrapped in parentheses:
+
+```lua
+return {
+  identity = (function(x) return x end),
+  answer = (42),
+}
+```
+
+A bare `function … end` or an unparenthesised expression fails to parse.
+
+## Toolchain
+
+`flake.nix` pins everything through [`purescript-overlay`](https://github.com/thomashoneyman/purescript-overlay): purs 0.15.16 (`purs-bin.purs-0_15_16`), spago 0.21.0 (`spago-bin.spago-0_21_0`), Lua 5.1 (`lua51Packages`). The `pslua` input tracks `github:purescript-lua/purescript-lua`; keep `flake.lock` reasonably current, since a long-stale pslua pin won't create the `--lua-output-file` directory and CI fails.
+
+## Releasing
+
+Tag-driven, with no GitHub Release or changelog entry. The full conventions live in the [package-set repo](https://github.com/purescript-lua/purescript-lua-package-sets/blob/master/CONTRIBUTING.md): push an annotated tag on `master`, bump this fork's `version` in the package set's `src/packages.dhall`, refresh `latest-compatible-sets.json`, and push a `psc-*` set tag.
diff --git a/CLAUDE.md b/CLAUDE.md
new file mode 100644
index 0000000..43c994c
--- /dev/null
+++ b/CLAUDE.md
@@ -0,0 +1 @@
+@AGENTS.md
diff --git a/bower.json b/bower.json
deleted file mode 100644
index 19b1992..0000000
--- a/bower.json
+++ /dev/null
@@ -1,39 +0,0 @@
-{
-  "name": "purescript-arrays",
-  "homepage": "https://github.com/purescript/purescript-arrays",
-  "license": "BSD-3-Clause",
-  "repository": {
-    "type": "git",
-    "url": "https://github.com/purescript/purescript-arrays.git"
-  },
-  "ignore": [
-    "**/.*",
-    "bower_components",
-    "node_modules",
-    "output",
-    "bower.json",
-    "package.json"
-  ],
-  "dependencies": {
-    "purescript-bifunctors": "^6.0.0",
-    "purescript-control": "^6.0.0",
-    "purescript-foldable-traversable": "^6.0.0",
-    "purescript-functions": "^6.0.0",
-    "purescript-maybe": "^6.0.0",
-    "purescript-nonempty": "^7.0.0",
-    "purescript-partial": "^4.0.0",
-    "purescript-prelude": "^6.0.0",
-    "purescript-safe-coerce": "^2.0.0",
-    "purescript-st": "^6.2.0",
-    "purescript-tailrec": "^6.0.0",
-    "purescript-tuples": "^7.0.0",
-    "purescript-unfoldable": "^6.0.0",
-    "purescript-unsafe-coerce": "^6.0.0"
-  },
-  "devDependencies": {
-    "purescript-assert": "^6.0.0",
-    "purescript-console": "^6.0.0",
-    "purescript-const": "^6.0.0",
-    "purescript-minibench": "^4.0.0"
-  }
-}
diff --git a/flake.lock b/flake.lock
index 780c119..6b6c417 100644
--- a/flake.lock
+++ b/flake.lock
@@ -16,23 +16,6 @@
         "type": "github"
       }
     },
-    "cabal-32": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1603716527,
-        "narHash": "sha256-X0TFfdD4KZpwl0Zr6x+PLxUt/VyKQfX7ylXHdmZIL+w=",
-        "owner": "haskell",
-        "repo": "cabal",
-        "rev": "48bf10787e27364730dd37a42b603cee8d6af7ee",
-        "type": "github"
-      },
-      "original": {
-        "owner": "haskell",
-        "ref": "3.2",
-        "repo": "cabal",
-        "type": "github"
-      }
-    },
     "cabal-34": {
       "flake": false,
       "locked": {
@@ -88,11 +71,11 @@
         "flake-utils": "flake-utils_2"
       },
       "locked": {
-        "lastModified": 1710161569,
-        "narHash": "sha256-lcIRIOFCdIWEGyKyG/tB4KvxM9zoWuBRDxW+T+mvIb0=",
+        "lastModified": 1763814099,
+        "narHash": "sha256-YazeA9u0JdxykexV6HHG5DMtsnwqXoiAcWPjncO1XHM=",
         "owner": "justinwoo",
         "repo": "easy-purescript-nix",
-        "rev": "117fd96acb69d7d1727df95b6fde9d8715e031fc",
+        "rev": "8fcd84f54d75d9007b2f1c7c9da5af843105a55f",
         "type": "github"
       },
       "original": {
@@ -101,35 +84,35 @@
         "type": "github"
       }
     },
-    "easyps": {
+    "flake-compat": {
       "flake": false,
       "locked": {
-        "lastModified": 1710161569,
-        "narHash": "sha256-lcIRIOFCdIWEGyKyG/tB4KvxM9zoWuBRDxW+T+mvIb0=",
-        "owner": "justinwoo",
-        "repo": "easy-purescript-nix",
-        "rev": "117fd96acb69d7d1727df95b6fde9d8715e031fc",
+        "lastModified": 1672831974,
+        "narHash": "sha256-z9k3MfslLjWQfnjBtEtJZdq3H7kyi2kQtUThfTgdRk0=",
+        "owner": "input-output-hk",
+        "repo": "flake-compat",
+        "rev": "45f2638735f8cdc40fe302742b79f248d23eb368",
         "type": "github"
       },
       "original": {
-        "owner": "justinwoo",
-        "repo": "easy-purescript-nix",
+        "owner": "input-output-hk",
+        "ref": "hkm/gitlab-fix",
+        "repo": "flake-compat",
         "type": "github"
       }
     },
-    "flake-compat": {
+    "flake-compat_2": {
       "flake": false,
       "locked": {
-        "lastModified": 1672831974,
-        "narHash": "sha256-z9k3MfslLjWQfnjBtEtJZdq3H7kyi2kQtUThfTgdRk0=",
-        "owner": "input-output-hk",
+        "lastModified": 1765121682,
+        "narHash": "sha256-4VBOP18BFeiPkyhy9o4ssBNQEvfvv1kXkasAYd0+rrA=",
+        "owner": "edolstra",
         "repo": "flake-compat",
-        "rev": "45f2638735f8cdc40fe302742b79f248d23eb368",
+        "rev": "65f23138d8d09a92e30f1e5c87611b23ef451bf3",
         "type": "github"
       },
       "original": {
-        "owner": "input-output-hk",
-        "ref": "hkm/gitlab-fix",
+        "owner": "edolstra",
         "repo": "flake-compat",
         "type": "github"
       }
@@ -139,11 +122,11 @@
         "systems": "systems"
       },
       "locked": {
-        "lastModified": 1710146030,
-        "narHash": "sha256-SZ5L6eA7HJ/nmkzGG7/ISclqe6oZdOZTNoesiInkXPQ=",
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "b1d9ab70662946ef0850d488da1c9019f3a9752a",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
         "type": "github"
       },
       "original": {
@@ -175,11 +158,11 @@
         "systems": "systems_3"
       },
       "locked": {
-        "lastModified": 1710146030,
-        "narHash": "sha256-SZ5L6eA7HJ/nmkzGG7/ISclqe6oZdOZTNoesiInkXPQ=",
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "b1d9ab70662946ef0850d488da1c9019f3a9752a",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
         "type": "github"
       },
       "original": {
@@ -188,68 +171,47 @@
         "type": "github"
       }
     },
-    "ghc-8.6.5-iohk": {
+    "hackage": {
       "flake": false,
       "locked": {
-        "lastModified": 1600920045,
-        "narHash": "sha256-DO6kxJz248djebZLpSzTGD6s8WRpNI9BTwUeOf5RwY8=",
+        "lastModified": 1781226159,
+        "narHash": "sha256-BD3MeXxK03Tnh1KxVKMYlU+H8hks+dVMOQLeriAkK8M=",
         "owner": "input-output-hk",
-        "repo": "ghc",
-        "rev": "95713a6ecce4551240da7c96b6176f980af75cae",
+        "repo": "hackage.nix",
+        "rev": "cc1f434e3407d58970261cbff2e4a5dab00b803b",
         "type": "github"
       },
       "original": {
         "owner": "input-output-hk",
-        "ref": "release/8.6.5-iohk",
-        "repo": "ghc",
+        "repo": "hackage.nix",
         "type": "github"
       }
     },
-    "ghc910X": {
-      "flake": false,
-      "locked": {
-        "lastModified": 1709693152,
-        "narHash": "sha256-j7K/oZLy1ZZIpOsjq101IF7cz/i/UxY1ofIeNUfuuXc=",
-        "ref": "ghc-9.10",
-        "rev": "21e3f3250e88640087a1a60bee2cc113bf04509f",
-        "revCount": 62524,
-        "submodules": true,
-        "type": "git",
-        "url": "https://gitlab.haskell.org/ghc/ghc"
-      },
-      "original": {
-        "ref": "ghc-9.10",
-        "submodules": true,
-        "type": "git",
-        "url": "https://gitlab.haskell.org/ghc/ghc"
-      }
-    },
-    "ghc911": {
+    "hackage-for-stackage": {
       "flake": false,
       "locked": {
-        "lastModified": 1710286031,
-        "narHash": "sha256-fz71zsU/ZukFMUsRNk2Ro3xTNMKsNrpvQtRtPqRI60c=",
-        "ref": "refs/heads/master",
-        "rev": "e6bfb85c842edca36754bb8914e725fbaa1a83a6",
-        "revCount": 62586,
-        "submodules": true,
-        "type": "git",
-        "url": "https://gitlab.haskell.org/ghc/ghc"
+        "lastModified": 1781226148,
+        "narHash": "sha256-95My9dq0a6wCV1v/78OJ+NUKBdD1TwyZomuTc/AxJFg=",
+        "owner": "input-output-hk",
+        "repo": "hackage.nix",
+        "rev": "6233e06fc1f6345f27324f55c485561848d784db",
+        "type": "github"
       },
       "original": {
-        "submodules": true,
-        "type": "git",
-        "url": "https://gitlab.haskell.org/ghc/ghc"
+        "owner": "input-output-hk",
+        "ref": "for-stackage",
+        "repo": "hackage.nix",
+        "type": "github"
       }
     },
-    "hackage": {
+    "hackage-internal": {
       "flake": false,
       "locked": {
-        "lastModified": 1710807758,
-        "narHash": "sha256-lQY4KSZQlMyKizC+Xbsl29hxNPHV52pRTDZac+vPaeU=",
+        "lastModified": 1750307553,
+        "narHash": "sha256-iiafNoeLHwlSLQTyvy8nPe2t6g5AV4PPcpMeH/2/DLs=",
         "owner": "input-output-hk",
         "repo": "hackage.nix",
-        "rev": "dc3cafd9dbaeebe37c96613a9d145e162cadcf79",
+        "rev": "f7867baa8817fab296528f4a4ec39d1c7c4da4f3",
         "type": "github"
       },
       "original": {
@@ -261,48 +223,50 @@
     "haskellNix": {
       "inputs": {
         "HTTP": "HTTP",
-        "cabal-32": "cabal-32",
         "cabal-34": "cabal-34",
         "cabal-36": "cabal-36",
         "cardano-shell": "cardano-shell",
         "flake-compat": "flake-compat",
-        "ghc-8.6.5-iohk": "ghc-8.6.5-iohk",
-        "ghc910X": "ghc910X",
-        "ghc911": "ghc911",
         "hackage": "hackage",
+        "hackage-for-stackage": "hackage-for-stackage",
+        "hackage-internal": "hackage-internal",
+        "hls": "hls",
         "hls-1.10": "hls-1.10",
         "hls-2.0": "hls-2.0",
+        "hls-2.10": "hls-2.10",
+        "hls-2.11": "hls-2.11",
+        "hls-2.12": "hls-2.12",
         "hls-2.2": "hls-2.2",
         "hls-2.3": "hls-2.3",
         "hls-2.4": "hls-2.4",
         "hls-2.5": "hls-2.5",
         "hls-2.6": "hls-2.6",
+        "hls-2.7": "hls-2.7",
+        "hls-2.8": "hls-2.8",
+        "hls-2.9": "hls-2.9",
         "hpc-coveralls": "hpc-coveralls",
-        "hydra": "hydra",
         "iserv-proxy": "iserv-proxy",
-        "nix-tools-static": "nix-tools-static",
         "nixpkgs": [
           "pslua",
           "haskellNix",
           "nixpkgs-unstable"
         ],
-        "nixpkgs-2003": "nixpkgs-2003",
-        "nixpkgs-2105": "nixpkgs-2105",
-        "nixpkgs-2111": "nixpkgs-2111",
-        "nixpkgs-2205": "nixpkgs-2205",
-        "nixpkgs-2211": "nixpkgs-2211",
         "nixpkgs-2305": "nixpkgs-2305",
         "nixpkgs-2311": "nixpkgs-2311",
+        "nixpkgs-2405": "nixpkgs-2405",
+        "nixpkgs-2411": "nixpkgs-2411",
+        "nixpkgs-2505": "nixpkgs-2505",
+        "nixpkgs-2511": "nixpkgs-2511",
         "nixpkgs-unstable": "nixpkgs-unstable",
         "old-ghc-nix": "old-ghc-nix",
         "stackage": "stackage"
       },
       "locked": {
-        "lastModified": 1710809412,
-        "narHash": "sha256-uLn/+4rBqk/+y5OPqe0LqUZHW7uEnWiljO/oGEx3L7c=",
+        "lastModified": 1781228148,
+        "narHash": "sha256-Qu6Zml4PHTgV1vs5RuLZzHuNOZYbeOtjeQq8yLIUbTU=",
         "owner": "input-output-hk",
         "repo": "haskell.nix",
-        "rev": "bc43eea89699683d1659eed3c3cc787e432ebfe7",
+        "rev": "fe9f2b0bfc6fc1bcc15eba41c729228135cda6ed",
         "type": "github"
       },
       "original": {
@@ -311,6 +275,22 @@
         "type": "github"
       }
     },
+    "hls": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1741604408,
+        "narHash": "sha256-tuq3+Ip70yu89GswZ7DSINBpwRprnWnl6xDYnS4GOsc=",
+        "owner": "haskell",
+        "repo": "haskell-language-server",
+        "rev": "682d6894c94087da5e566771f25311c47e145359",
+        "type": "github"
+      },
+      "original": {
+        "owner": "haskell",
+        "repo": "haskell-language-server",
+        "type": "github"
+      }
+    },
     "hls-1.10": {
       "flake": false,
       "locked": {
@@ -345,6 +325,57 @@
         "type": "github"
       }
     },
+    "hls-2.10": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1743069404,
+        "narHash": "sha256-q4kDFyJDDeoGqfEtrZRx4iqMVEC2MOzCToWsFY+TOzY=",
+        "owner": "haskell",
+        "repo": "haskell-language-server",
+        "rev": "2318c61db3a01e03700bd4b05665662929b7fe8b",
+        "type": "github"
+      },
+      "original": {
+        "owner": "haskell",
+        "ref": "2.10.0.0",
+        "repo": "haskell-language-server",
+        "type": "github"
+      }
+    },
+    "hls-2.11": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1747306193,
+        "narHash": "sha256-/MmtpF8+FyQlwfKHqHK05BdsxC9LHV70d/FiMM7pzBM=",
+        "owner": "haskell",
+        "repo": "haskell-language-server",
+        "rev": "46ef4523ea4949f47f6d2752476239f1c6d806fe",
+        "type": "github"
+      },
+      "original": {
+        "owner": "haskell",
+        "ref": "2.11.0.0",
+        "repo": "haskell-language-server",
+        "type": "github"
+      }
+    },
+    "hls-2.12": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1758709460,
+        "narHash": "sha256-xkI8MIIVEVARskfWbGAgP5sHG/lyeKnkm0LIOJ19X5w=",
+        "owner": "haskell",
+        "repo": "haskell-language-server",
+        "rev": "7d983de4fa7ff54369f6dd31444bdb9869aec83e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "haskell",
+        "ref": "2.12.0.0",
+        "repo": "haskell-language-server",
+        "type": "github"
+      }
+    },
     "hls-2.2": {
       "flake": false,
       "locked": {
@@ -430,124 +461,97 @@
         "type": "github"
       }
     },
-    "hpc-coveralls": {
+    "hls-2.7": {
       "flake": false,
       "locked": {
-        "lastModified": 1607498076,
-        "narHash": "sha256-8uqsEtivphgZWYeUo5RDUhp6bO9j2vaaProQxHBltQk=",
-        "owner": "sevanspowell",
-        "repo": "hpc-coveralls",
-        "rev": "14df0f7d229f4cd2e79f8eabb1a740097fdfa430",
+        "lastModified": 1708965829,
+        "narHash": "sha256-LfJ+TBcBFq/XKoiNI7pc4VoHg4WmuzsFxYJ3Fu+Jf+M=",
+        "owner": "haskell",
+        "repo": "haskell-language-server",
+        "rev": "50322b0a4aefb27adc5ec42f5055aaa8f8e38001",
         "type": "github"
       },
       "original": {
-        "owner": "sevanspowell",
-        "repo": "hpc-coveralls",
+        "owner": "haskell",
+        "ref": "2.7.0.0",
+        "repo": "haskell-language-server",
         "type": "github"
       }
     },
-    "hydra": {
-      "inputs": {
-        "nix": "nix",
-        "nixpkgs": [
-          "pslua",
-          "haskellNix",
-          "hydra",
-          "nix",
-          "nixpkgs"
-        ]
-      },
-      "locked": {
-        "lastModified": 1671755331,
-        "narHash": "sha256-hXsgJj0Cy0ZiCiYdW2OdBz5WmFyOMKuw4zyxKpgUKm4=",
-        "owner": "NixOS",
-        "repo": "hydra",
-        "rev": "f48f00ee6d5727ae3e488cbf9ce157460853fea8",
-        "type": "github"
-      },
-      "original": {
-        "id": "hydra",
-        "type": "indirect"
-      }
-    },
-    "iserv-proxy": {
+    "hls-2.8": {
       "flake": false,
       "locked": {
-        "lastModified": 1708894040,
-        "narHash": "sha256-Rv+PajrnuJ6AeyhtqzMN+bcR8z9+aEnrUass+N951CQ=",
-        "owner": "stable-haskell",
-        "repo": "iserv-proxy",
-        "rev": "2f2a318fd8837f8063a0d91f329aeae29055fba9",
+        "lastModified": 1715153580,
+        "narHash": "sha256-Vi/iUt2pWyUJlo9VrYgTcbRviWE0cFO6rmGi9rmALw0=",
+        "owner": "haskell",
+        "repo": "haskell-language-server",
+        "rev": "dd1be1beb16700de59e0d6801957290bcf956a0a",
         "type": "github"
       },
       "original": {
-        "owner": "stable-haskell",
-        "ref": "iserv-syms",
-        "repo": "iserv-proxy",
+        "owner": "haskell",
+        "ref": "2.8.0.0",
+        "repo": "haskell-language-server",
         "type": "github"
       }
     },
-    "lowdown-src": {
+    "hls-2.9": {
       "flake": false,
       "locked": {
-        "lastModified": 1633514407,
-        "narHash": "sha256-Dw32tiMjdK9t3ETl5fzGrutQTzh2rufgZV4A/BbxuD4=",
-        "owner": "kristapsdz",
-        "repo": "lowdown",
-        "rev": "d2c2b44ff6c27b936ec27358a2653caaef8f73b8",
+        "lastModified": 1719993701,
+        "narHash": "sha256-wy348++MiMm/xwtI9M3vVpqj2qfGgnDcZIGXw8sF1sA=",
+        "owner": "haskell",
+        "repo": "haskell-language-server",
+        "rev": "90319a7e62ab93ab65a95f8f2bcf537e34dae76a",
         "type": "github"
       },
       "original": {
-        "owner": "kristapsdz",
-        "repo": "lowdown",
+        "owner": "haskell",
+        "ref": "2.9.0.1",
+        "repo": "haskell-language-server",
         "type": "github"
       }
     },
-    "nix": {
-      "inputs": {
-        "lowdown-src": "lowdown-src",
-        "nixpkgs": "nixpkgs_2",
-        "nixpkgs-regression": "nixpkgs-regression"
-      },
+    "hpc-coveralls": {
+      "flake": false,
       "locked": {
-        "lastModified": 1661606874,
-        "narHash": "sha256-9+rpYzI+SmxJn+EbYxjGv68Ucp22bdFUSy/4LkHkkDQ=",
-        "owner": "NixOS",
-        "repo": "nix",
-        "rev": "11e45768b34fdafdcf019ddbd337afa16127ff0f",
+        "lastModified": 1607498076,
+        "narHash": "sha256-8uqsEtivphgZWYeUo5RDUhp6bO9j2vaaProQxHBltQk=",
+        "owner": "sevanspowell",
+        "repo": "hpc-coveralls",
+        "rev": "14df0f7d229f4cd2e79f8eabb1a740097fdfa430",
         "type": "github"
       },
       "original": {
-        "owner": "NixOS",
-        "ref": "2.11.0",
-        "repo": "nix",
+        "owner": "sevanspowell",
+        "repo": "hpc-coveralls",
         "type": "github"
       }
     },
-    "nix-tools-static": {
+    "iserv-proxy": {
       "flake": false,
       "locked": {
-        "lastModified": 1706266250,
-        "narHash": "sha256-9t+GRk3eO9muCtKdNAwBtNBZ5dH1xHcnS17WaQyftwA=",
-        "owner": "input-output-hk",
-        "repo": "haskell-nix-example",
-        "rev": "580cb6db546a7777dad3b9c0fa487a366c045c4e",
+        "lastModified": 1778457436,
+        "narHash": "sha256-bzZAHGzwcQGzBTipJuUs9tvMGO28kp0373zqnpn0g5A=",
+        "owner": "stable-haskell",
+        "repo": "iserv-proxy",
+        "rev": "8cdc446f8e2d91b120ecc075063e9475d387df52",
         "type": "github"
       },
       "original": {
-        "owner": "input-output-hk",
-        "ref": "nix",
-        "repo": "haskell-nix-example",
+        "owner": "stable-haskell",
+        "ref": "iserv-syms",
+        "repo": "iserv-proxy",
         "type": "github"
       }
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1711703276,
-        "narHash": "sha256-iMUFArF0WCatKK6RzfUJknjem0H9m4KgorO/p3Dopkk=",
+        "lastModified": 1781074563,
+        "narHash": "sha256-md8WlXOlfnIeHeOScMTTHFyf2d6iaTwPl2apR5EQ3P4=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "d8fe5e6c92d0d190646fb9f1056741a229980089",
+        "rev": "9ae611a455b90cf061d8f332b977e387bda8e1ca",
         "type": "github"
       },
       "original": {
@@ -556,162 +560,114 @@
         "type": "indirect"
       }
     },
-    "nixpkgs-2003": {
-      "locked": {
-        "lastModified": 1620055814,
-        "narHash": "sha256-8LEHoYSJiL901bTMVatq+rf8y7QtWuZhwwpKE2fyaRY=",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "1db42b7fe3878f3f5f7a4f2dc210772fd080e205",
-        "type": "github"
-      },
-      "original": {
-        "owner": "NixOS",
-        "ref": "nixpkgs-20.03-darwin",
-        "repo": "nixpkgs",
-        "type": "github"
-      }
-    },
-    "nixpkgs-2105": {
-      "locked": {
-        "lastModified": 1659914493,
-        "narHash": "sha256-lkA5X3VNMKirvA+SUzvEhfA7XquWLci+CGi505YFAIs=",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "022caabb5f2265ad4006c1fa5b1ebe69fb0c3faf",
-        "type": "github"
-      },
-      "original": {
-        "owner": "NixOS",
-        "ref": "nixpkgs-21.05-darwin",
-        "repo": "nixpkgs",
-        "type": "github"
-      }
-    },
-    "nixpkgs-2111": {
+    "nixpkgs-2305": {
       "locked": {
-        "lastModified": 1659446231,
-        "narHash": "sha256-hekabNdTdgR/iLsgce5TGWmfIDZ86qjPhxDg/8TlzhE=",
+        "lastModified": 1705033721,
+        "narHash": "sha256-K5eJHmL1/kev6WuqyqqbS1cdNnSidIZ3jeqJ7GbrYnQ=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "eabc38219184cc3e04a974fe31857d8e0eac098d",
+        "rev": "a1982c92d8980a0114372973cbdfe0a307f1bdea",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixpkgs-21.11-darwin",
+        "ref": "nixpkgs-23.05-darwin",
         "repo": "nixpkgs",
         "type": "github"
       }
     },
-    "nixpkgs-2205": {
+    "nixpkgs-2311": {
       "locked": {
-        "lastModified": 1685573264,
-        "narHash": "sha256-Zffu01pONhs/pqH07cjlF10NnMDLok8ix5Uk4rhOnZQ=",
+        "lastModified": 1719957072,
+        "narHash": "sha256-gvFhEf5nszouwLAkT9nWsDzocUTqLWHuL++dvNjMp9I=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "380be19fbd2d9079f677978361792cb25e8a3635",
+        "rev": "7144d6241f02d171d25fba3edeaf15e0f2592105",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixpkgs-22.05-darwin",
+        "ref": "nixpkgs-23.11-darwin",
         "repo": "nixpkgs",
         "type": "github"
       }
     },
-    "nixpkgs-2211": {
+    "nixpkgs-2405": {
       "locked": {
-        "lastModified": 1688392541,
-        "narHash": "sha256-lHrKvEkCPTUO+7tPfjIcb7Trk6k31rz18vkyqmkeJfY=",
+        "lastModified": 1735564410,
+        "narHash": "sha256-HB/FA0+1gpSs8+/boEavrGJH+Eq08/R2wWNph1sM1Dg=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "ea4c80b39be4c09702b0cb3b42eab59e2ba4f24b",
+        "rev": "1e7a8f391f1a490460760065fa0630b5520f9cf8",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixpkgs-22.11-darwin",
+        "ref": "nixpkgs-24.05-darwin",
         "repo": "nixpkgs",
         "type": "github"
       }
     },
-    "nixpkgs-2305": {
+    "nixpkgs-2411": {
       "locked": {
-        "lastModified": 1701362232,
-        "narHash": "sha256-GVdzxL0lhEadqs3hfRLuj+L1OJFGiL/L7gCcelgBlsw=",
+        "lastModified": 1751290243,
+        "narHash": "sha256-kNf+obkpJZWar7HZymXZbW+Rlk3HTEIMlpc6FCNz0Ds=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "d2332963662edffacfddfad59ff4f709dde80ffe",
+        "rev": "5ab036a8d97cb9476fbe81b09076e6e91d15e1b6",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixpkgs-23.05-darwin",
+        "ref": "nixpkgs-24.11-darwin",
         "repo": "nixpkgs",
         "type": "github"
       }
     },
-    "nixpkgs-2311": {
+    "nixpkgs-2505": {
       "locked": {
-        "lastModified": 1701386440,
-        "narHash": "sha256-xI0uQ9E7JbmEy/v8kR9ZQan6389rHug+zOtZeZFiDJk=",
+        "lastModified": 1764560356,
+        "narHash": "sha256-M5aFEFPppI4UhdOxwdmceJ9bDJC4T6C6CzCK1E2FZyo=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "293822e55ec1872f715a66d0eda9e592dc14419f",
+        "rev": "6c8f0cca84510cc79e09ea99a299c9bc17d03cb6",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixpkgs-23.11-darwin",
+        "ref": "nixpkgs-25.05-darwin",
         "repo": "nixpkgs",
         "type": "github"
       }
     },
-    "nixpkgs-regression": {
+    "nixpkgs-2511": {
       "locked": {
-        "lastModified": 1643052045,
-        "narHash": "sha256-uGJ0VXIhWKGXxkeNnq4TvV3CIOkUJ3PAoLZ3HMzNVMw=",
+        "lastModified": 1775749320,
+        "narHash": "sha256-msT6frWJSQ2WR+0cpk+KPcZdLTLagUIsJwQwIX9JNSo=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "215d4d0fd80ca5163643b03a33fde804a29cc1e2",
+        "rev": "74b87959b2d16f59f54d8559cf3cf26b9d907949",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
+        "ref": "nixpkgs-25.11-darwin",
         "repo": "nixpkgs",
-        "rev": "215d4d0fd80ca5163643b03a33fde804a29cc1e2",
         "type": "github"
       }
     },
     "nixpkgs-unstable": {
       "locked": {
-        "lastModified": 1694822471,
-        "narHash": "sha256-6fSDCj++lZVMZlyqOe9SIOL8tYSBz1bI8acwovRwoX8=",
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "47585496bcb13fb72e4a90daeea2f434e2501998",
-        "type": "github"
-      },
-      "original": {
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "47585496bcb13fb72e4a90daeea2f434e2501998",
-        "type": "github"
-      }
-    },
-    "nixpkgs_2": {
-      "locked": {
-        "lastModified": 1657693803,
-        "narHash": "sha256-G++2CJ9u0E7NNTAi9n5G8TdDmGJXcIjkJ3NF8cetQB8=",
+        "lastModified": 1775888245,
+        "narHash": "sha256-nwASzrRDD1JBEu/o8ekKYEXm/oJW6EMCzCRdrwcLe90=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "365e1b3a859281cf11b94f87231adeabbdd878a2",
+        "rev": "13043924aaa7375ce482ebe2494338e058282925",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixos-22.05-small",
+        "ref": "nixpkgs-unstable",
         "repo": "nixpkgs",
         "type": "github"
       }
@@ -745,35 +701,56 @@
         ]
       },
       "locked": {
-        "lastModified": 1711822377,
-        "narHash": "sha256-3cqI8lL04RZA7RrLImYzGsOOrE2Z5UpXzEvnvT9HqmA=",
-        "owner": "Unisay",
+        "lastModified": 1781449244,
+        "narHash": "sha256-evfLWZ+i55b0cSfd/jgU5mXuBg2KDEP5WhEj2iuzIiM=",
+        "owner": "purescript-lua",
         "repo": "purescript-lua",
-        "rev": "ccc2df825af5a6abe33d663ecdd8eb3ab9feb63a",
+        "rev": "94c13cecd1146494de56196a7badb3b1374d364d",
         "type": "github"
       },
       "original": {
-        "owner": "Unisay",
+        "owner": "purescript-lua",
         "repo": "purescript-lua",
         "type": "github"
       }
     },
+    "purescript-overlay": {
+      "inputs": {
+        "flake-compat": "flake-compat_2",
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1780972251,
+        "narHash": "sha256-PwHYPpfLP+WjSwj765zJ1N0Xp4ET3+8vRqxJ031ua3M=",
+        "owner": "thomashoneyman",
+        "repo": "purescript-overlay",
+        "rev": "1cf88ab9d83596db0e0c0d304a16809c410e2917",
+        "type": "github"
+      },
+      "original": {
+        "owner": "thomashoneyman",
+        "repo": "purescript-overlay",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
-        "easyps": "easyps",
         "flake-utils": "flake-utils",
         "nixpkgs": "nixpkgs",
-        "pslua": "pslua"
+        "pslua": "pslua",
+        "purescript-overlay": "purescript-overlay"
       }
     },
     "stackage": {
       "flake": false,
       "locked": {
-        "lastModified": 1710461339,
-        "narHash": "sha256-l2/ekwA4Z4NjiaCZytZrBTag2VaAOBUvsNttsH6kH4E=",
+        "lastModified": 1781225038,
+        "narHash": "sha256-eG1GGyHdEI8y2chHOmgx0rypbHyjIn9ViawYmN2CEd4=",
         "owner": "input-output-hk",
         "repo": "stackage.nix",
-        "rev": "724970b7dc837bf0d813b91f821948c3c5cc719f",
+        "rev": "e2af13c92a93da96529a874428acae18d085bafe",
         "type": "github"
       },
       "original": {
diff --git a/flake.nix b/flake.nix
index fbde00f..5198865 100644
--- a/flake.nix
+++ b/flake.nix
@@ -4,34 +4,45 @@
   inputs = {
     flake-utils.url = "github:numtide/flake-utils";
     nixpkgs.url = "nixpkgs/nixos-unstable";
-    easyps = {
-      url = "github:justinwoo/easy-purescript-nix";
-      flake = false;
+    purescript-overlay = {
+      url = "github:thomashoneyman/purescript-overlay";
+      inputs.nixpkgs.follows = "nixpkgs";
     };
-    pslua.url = "github:Unisay/purescript-lua";
+    pslua.url = "github:purescript-lua/purescript-lua";
   };
 
-  outputs = { self, nixpkgs, flake-utils, easyps, pslua }:
+  outputs = { self, nixpkgs, flake-utils, purescript-overlay, pslua }:
     flake-utils.lib.eachDefaultSystem (system:
       let
-        p = nixpkgs.legacyPackages.${system};
-        e = import easyps { pkgs = p; };
-        l = p.lua51Packages;
+        pkgs = import nixpkgs {
+          inherit system;
+          overlays = [ purescript-overlay.overlays.default ];
+        };
       in {
-        devShell = p.mkShell {
-          buildInputs = [
-              p.dhall
-              l.lua
-              l.luacheck
-              p.luaformatter
-              p.nixfmt
-              pslua.packages.${system}.default
-              e.purs-0_15_15
-              e.purs-tidy
-              e.spago
-              p.treefmt
-            ];
+        devShell = pkgs.mkShell {
+          buildInputs = with pkgs; [
+            dhall
+            lua51Packages.lua
+            lua51Packages.luacheck
+            luaformatter
+            nixfmt-rfc-style
+            pslua.packages.${system}.default
+            purs-bin.purs-0_15_16
+            spago-bin.spago-0_21_0
+            treefmt
+          ];
         };
       });
-}
 
+  # --- Flake Local Nix Configuration ----------------------------
+  nixConfig = {
+    extra-substituters = [
+      "https://cache.iog.io"
+      "https://purescript-lua.cachix.org"
+    ];
+    extra-trusted-public-keys = [
+      "hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ="
+      "purescript-lua.cachix.org-1:yLs4ei2HtnuPtzLekOrW3xdfm95+Etw15gwgyIGTayA="
+    ];
+  };
+}
diff --git a/package.json b/package.json
deleted file mode 100644
index ee9cb3a..0000000
--- a/package.json
+++ /dev/null
@@ -1,17 +0,0 @@
-{
-  "private": true,
-  "scripts": {
-    "clean": "rimraf output && rimraf .pulp-cache",
-    "build": "eslint src && pulp build -- --censor-lib --strict",
-    "test": "pulp test",
-    "bench:build": "pulp build --include bench -- --censor-lib --strict",
-    "bench:run": "node --expose-gc -e \"require('./output/Bench.Main/index.js').main()\"",
-    "bench": "npm run bench:build && npm run bench:run"
-  },
-  "devDependencies": {
-    "eslint": "^7.15.0",
-    "pulp": "16.0.0-0",
-    "purescript-psa": "^0.8.2",
-    "rimraf": "^3.0.2"
-  }
-}
diff --git a/packages.dhall b/packages.dhall
index cd08d59..03ddf10 100644
--- a/packages.dhall
+++ b/packages.dhall
@@ -3,7 +3,7 @@ let upstream-ps =
         sha256:ae8a25645e81ff979beb397a21e5d272fae7c9ebdb021a96b1b431388c8f3c34
 
 let upstream-lua =
-      https://github.com/Unisay/purescript-lua-package-sets/releases/download/psc-0.15.15-20240338/packages.dhall
+      https://github.com/purescript-lua/purescript-lua-package-sets/releases/download/psc-0.15.15-20240338/packages.dhall
         sha256:8a7527f82c9a8a9ec2c1c945bf45a75faa4bf847609b8ada570c1cd969bca7eb
 
 in  upstream-ps // upstream-lua
diff --git a/scripts/build b/scripts/build
index 6bee995..f0ef609 100755
--- a/scripts/build
+++ b/scripts/build
@@ -1,4 +1,5 @@
 #!/usr/bin/env bash
+set -euo pipefail
 
 echo "Building..."
 
diff --git a/scripts/test b/scripts/test
new file mode 100755
index 0000000..67bf2dc
--- /dev/null
+++ b/scripts/test
@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+echo "Running regression tests..."
+
+lua test/regression/array_st.lua
diff --git a/src/Data/Array.lua b/src/Data/Array.lua
index 5fc0c23..733d37d 100644
--- a/src/Data/Array.lua
+++ b/src/Data/Array.lua
@@ -41,7 +41,7 @@ return {
   length = (function(xs) return #xs end),
   unconsImpl = (function(empty, next, xs)
     if #xs == 0 then return empty({}) end
-    return next(xs[1])(table.pack(table.unpack(xs, 2)))
+    return next(xs[1])({ unpack(xs, 2) })
   end),
   indexImpl = (function(just, nothing, xs, i)
     if i < 0 or i >= #xs then
@@ -67,19 +67,19 @@ return {
   end),
   _insertAt = (function(just, nothing, i, a, l)
     if i < 0 or i > #l then return nothing end
-    local l1 = table.pack(table.unpack(l))
+    local l1 = { unpack(l) }
     table.insert(l1, i + 1, a)
     return just(l1)
   end),
   _deleteAt = (function(just, nothing, i, l)
     if i < 0 or i >= #l then return nothing end
-    local l1 = table.pack(table.unpack(l))
+    local l1 = { unpack(l) }
     table.remove(l1, i + 1)
     return just(l1)
   end),
   _updateAt = (function(just, nothing, i, f, l)
     if i < 0 or i >= #l then return nothing end
-    local l1 = table.pack(table.unpack(l))
+    local l1 = { unpack(l) }
     l1[i + 1] = f(l1[i + 1])
     return just(l1)
   end),
@@ -185,8 +185,8 @@ return {
 
     return function(compare, fromOrdering, xs)
       if #xs < 2 then return xs end
-      local out = table.pack(table.unpack(xs))
-      local slice = table.pack(table.unpack(xs))
+      local out = { unpack(xs) }
+      local slice = { unpack(xs) }
       mergeFromTo(compare, fromOrdering, out, slice, 0, #xs)
       return out
     end
diff --git a/src/Data/Array/ST.lua b/src/Data/Array/ST.lua
index a7a14e3..bac8b15 100644
--- a/src/Data/Array/ST.lua
+++ b/src/Data/Array/ST.lua
@@ -1,4 +1,20 @@
-local function copyImpl(xs) return function() return table.move(xs, 1, #xs, 1, {}) end end
+-- Lua 5.1 has no table.move, so provide an overlap-safe equivalent with the
+-- same semantics as Lua 5.3's table.move(a1, f, e, t, a2): copy a1[f..e] to
+-- a2 starting at t, iterating backwards when the source and destination overlap
+-- so a forward shift to the right does not clobber elements before reading them.
+local function move(a1, f, e, t, a2)
+  a2 = a2 or a1
+  if e >= f then
+    if a1 ~= a2 or t <= f or t > e then
+      for i = 0, e - f do a2[t + i] = a1[f + i] end
+    else
+      for i = e - f, 0, -1 do a2[t + i] = a1[f + i] end
+    end
+  end
+  return a2
+end
+
+local function copyImpl(xs) return function() return move(xs, 1, #xs, 1, {}) end end
 
 return {
   new = (function() return {} end),
@@ -25,7 +41,7 @@ return {
     end
   end),
   pushAllImpl = (function(as, xs)
-    local r = table.move(as, 1, #as, #xs + 1, xs)
+    local r = move(as, 1, #as, #xs + 1, xs)
     return #r
   end),
   shiftImpl = (function(just, nothing, xs)
@@ -36,10 +52,10 @@ return {
     end
   end),
   unshiftAllImpl = (function(as, xs)
-    local r = table.move(as, 1, #as, 1, xs)
+    local r = move(as, 1, #as, 1, xs)
     return #r
   end),
-  spliceImpl = (function(i, howMany, bs, xs) return table.move(xs, i + howMany + 1, #xs, i + #bs + 1, xs) end),
+  spliceImpl = (function(i, howMany, bs, xs) return move(xs, i + howMany + 1, #xs, i + #bs + 1, xs) end),
   unsafeFreezeImpl = (function(xs) return xs end),
   unsafeThawImpl = (function(xs) return xs end),
   freeze = (copyImpl),
@@ -84,7 +100,7 @@ return {
 
     return function(compare, fromOrdering, xs)
       if #xs < 2 then return xs end
-      mergeFromTo(compare, fromOrdering, xs, table.move(xs, 1, #xs, 1, {}), 0, #xs)
+      mergeFromTo(compare, fromOrdering, xs, move(xs, 1, #xs, 1, {}), 0, #xs)
       return xs
     end
   end)()),
diff --git a/test/regression/array_st.lua b/test/regression/array_st.lua
new file mode 100644
index 0000000..33d3a05
--- /dev/null
+++ b/test/regression/array_st.lua
@@ -0,0 +1,156 @@
+-- Regression guard for the Lua 5.1 FFI rewrite of the array foreign modules.
+--
+-- Lua 5.1 has no table.pack / table.unpack / table.move, so Data/Array.lua now
+-- uses `{ unpack(...) }` and Data/Array/ST.lua uses a hand-written overlap-safe
+-- `move`. These checks pin the behaviour of exactly those rewritten paths,
+-- especially the two overlap directions of `move` that a naive copy gets wrong.
+--
+-- Run from the repo root: `lua test/regression/array_st.lua`.
+
+local ST = dofile("src/Data/Array/ST.lua")
+local A = dofile("src/Data/Array.lua")
+
+local failures = 0
+
+local function eqArray(a, b)
+  if #a ~= #b then return false end
+  for i = 1, #a do
+    if a[i] ~= b[i] then return false end
+  end
+  return true
+end
+
+local function show(a)
+  local parts = {}
+  for i = 1, #a do parts[i] = tostring(a[i]) end
+  return "{" .. table.concat(parts, ", ") .. "}"
+end
+
+local function checkArray(name, got, want)
+  if eqArray(got, want) then
+    print("ok   - " .. name)
+  else
+    failures = failures + 1
+    print("FAIL - " .. name .. ": got " .. show(got) .. ", want " .. show(want))
+  end
+end
+
+local function check(name, cond, detail)
+  if cond then
+    print("ok   - " .. name)
+  else
+    failures = failures + 1
+    print("FAIL - " .. name .. ": " .. tostring(detail))
+  end
+end
+
+--------------------------------------------------------------------------------
+-- Data/Array/ST.lua: move-based operations -----------------------------------
+
+-- freeze (= copyImpl, the move-to-fresh-table path) is an independent copy.
+do
+  local xs = { 1, 2, 3 }
+  local copy = ST.freeze(xs)()
+  checkArray("freeze copies", copy, { 1, 2, 3 })
+  copy[1] = 99
+  check("freeze is independent", xs[1] == 1, "source mutated to " .. tostring(xs[1]))
+end
+
+-- pushAllImpl appends and reports the new length.
+do
+  local xs = { 1, 2 }
+  local n = ST.pushAllImpl({ 3, 4, 5 }, xs)
+  checkArray("pushAllImpl appends", xs, { 1, 2, 3, 4, 5 })
+  check("pushAllImpl returns length", n == 5, "got " .. tostring(n))
+end
+
+-- spliceImpl shifting the tail LEFT (destination before source: forward copy).
+do
+  local xs = { 10, 20, 30, 40, 50 }
+  ST.spliceImpl(1, 1, {}, xs) -- move(xs, 3, 5, 2, xs)
+  checkArray("spliceImpl shift-left overlap", xs, { 10, 30, 40, 50, 50 })
+end
+
+-- spliceImpl shifting the tail RIGHT (destination inside source: must copy
+-- backwards or it clobbers). This is the case a naive forward loop breaks.
+do
+  local xs = { 1, 2, 3, 4 }
+  ST.spliceImpl(0, 0, { 9 }, xs) -- move(xs, 1, 4, 2, xs)
+  checkArray("spliceImpl shift-right overlap", xs, { 1, 1, 2, 3, 4 })
+end
+
+-- sortByImpl sorts in place (it copies through move internally).
+do
+  local function compare(x) return function(y)
+    if x < y then return -1 elseif x > y then return 1 else return 0 end
+  end end
+  local function fromOrdering(o) return o end
+  local xs = { 3, 1, 2, 1 }
+  local sorted = ST.sortByImpl(compare, fromOrdering, xs)
+  checkArray("sortByImpl sorts ascending", sorted, { 1, 1, 2, 3 })
+end
+
+-- sortByImpl is stable: records with equal keys keep their input order.
+do
+  local function byKey(x) return function(y)
+    if x.k < y.k then return -1 elseif x.k > y.k then return 1 else return 0 end
+  end end
+  local function fromOrdering(o) return o end
+  -- Two elements share key 1 ("a" before "b"); a stable sort keeps a before b.
+  local xs = {
+    { k = 1, id = "a" },
+    { k = 0, id = "c" },
+    { k = 1, id = "b" },
+  }
+  ST.sortByImpl(byKey, fromOrdering, xs)
+  local keys, ids = {}, {}
+  for i = 1, #xs do keys[i], ids[i] = xs[i].k, xs[i].id end
+  checkArray("sortByImpl orders by key", keys, { 0, 1, 1 })
+  check("sortByImpl is stable on equal keys", ids[1] == "c" and ids[2] == "a" and ids[3] == "b",
+    "got order " .. table.concat(ids, ","))
+end
+
+--------------------------------------------------------------------------------
+-- Data/Array.lua: unpack-based operations ------------------------------------
+
+local function just(x) return { tag = "just", value = x } end
+local nothing = { tag = "nothing" }
+
+-- unconsImpl splits head / tail; the tail is `{ unpack(xs, 2) }`.
+do
+  local function empty(_) return { tag = "empty" } end
+  local function next(h) return function(t) return { tag = "cons", head = h, tail = t } end end
+  local r = A.unconsImpl(empty, next, { 1, 2, 3 })
+  check("unconsImpl head", r.head == 1, "got " .. tostring(r.head))
+  checkArray("unconsImpl tail", r.tail, { 2, 3 })
+  check("unconsImpl empty", A.unconsImpl(empty, next, {}).tag == "empty", "non-empty result")
+end
+
+-- _insertAt copies via unpack, then inserts; the source is left untouched.
+do
+  local src = { 1, 2, 3 }
+  local r = A._insertAt(just, nothing, 1, 99, src)
+  checkArray("_insertAt result", r.value, { 1, 99, 2, 3 })
+  checkArray("_insertAt keeps source", src, { 1, 2, 3 })
+  check("_insertAt out of range", A._insertAt(just, nothing, 9, 0, src).tag == "nothing", "expected nothing")
+end
+
+-- _deleteAt copies via unpack, then removes.
+do
+  local r = A._deleteAt(just, nothing, 1, { 1, 2, 3 })
+  checkArray("_deleteAt result", r.value, { 1, 3 })
+end
+
+-- _updateAt copies via unpack, then updates one slot.
+do
+  local function times100(x) return x * 100 end
+  local r = A._updateAt(just, nothing, 1, times100, { 1, 2, 3 })
+  checkArray("_updateAt result", r.value, { 1, 200, 3 })
+end
+
+--------------------------------------------------------------------------------
+
+if failures > 0 then
+  error(failures .. " regression check(s) failed")
+end
+print("purescript-lua-arrays: all FFI regression checks passed")