From 63e22e85c69aca47e41b155932464d25b71d89c2 Mon Sep 17 00:00:00 2001
From: Thomas Honeyman <hello@thomashoneyman.com>
Date: Thu, 15 Oct 2026 18:04:06 +0000
Subject: [PATCH 1/7] Migrate package configuration and CI to Spago

---
 .github/workflows/ci.yml | 33 +++++++++++----------------------
 .gitignore               |  4 +++-
 .tidyrc.json             | 10 ++++++++++
 CHANGELOG.md             | 10 +++-------
 bower.json               | 32 --------------------------------
 examples/spago.yaml      | 17 +++++++++++++++++
 package.json             | 15 +++++++++------
 spago.yaml               | 20 ++++++++++++++++++++
 8 files changed, 73 insertions(+), 68 deletions(-)
 create mode 100644 .tidyrc.json
 delete mode 100644 bower.json
 create mode 100644 examples/spago.yaml
 create mode 100644 spago.yaml

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c69237a..0f3a6c1 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -6,30 +6,19 @@ on:
   pull_request:
     branches: [master]
 
+permissions:
+  contents: read
+
 jobs:
   build:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-
-      - uses: purescript-contrib/setup-purescript@main
-        with:
-          purescript: "unstable"
-
-      - uses: actions/setup-node@v2
+      - uses: actions/checkout@v6
+      - uses: actions/setup-node@v6
         with:
-          node-version: "14.x"
-
-      - name: Install dependencies
-        run: |
-          npm install -g bower
-          npm install
-          bower install --production
-
-      - name: Build source
-        run: npm run-script build
-
-      - name: Run tests
-        run: |
-          bower install
-          npm run-script test --if-present
+          node-version: "24"
+      - run: npm install
+      - run: npm run build
+      - run: npm run build:example
+      - run: npm run example
+      - run: npm run format:check
diff --git a/.gitignore b/.gitignore
index 2c02232..afb2a45 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,7 +1,9 @@
 /.*
 !/.gitignore
 !/.github/
-package-lock.json
+!/.tidyrc.json
+/package-lock.json
+/spago.lock
 /bower_components/
 /node_modules/
 /output/
diff --git a/.tidyrc.json b/.tidyrc.json
new file mode 100644
index 0000000..9e39cf1
--- /dev/null
+++ b/.tidyrc.json
@@ -0,0 +1,10 @@
+{
+  "importSort": "ide",
+  "importWrap": "source",
+  "indent": 2,
+  "operatorsFile": null,
+  "ribbon": 1,
+  "typeArrowPlacement": "first",
+  "unicode": "never",
+  "width": null
+}
diff --git a/CHANGELOG.md b/CHANGELOG.md
index de3ecb5..53caec3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,16 +2,12 @@
 
 Notable changes to this project are documented in this file. The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
-
-Breaking changes:
-
-New features:
-
-Bugfixes:
+## [v6.0.1](https://github.com/purescript/purescript-validation/releases/tag/v6.0.1)
 
 Other improvements:
 
+- Migrate from Bower/Pulp to Spago, update CI and formatting, and restore the runnable example.
+
 ## [v6.0.0](https://github.com/purescript/purescript-validation/releases/tag/v6.0.0) - 2022-04-27
 
 Breaking changes:
diff --git a/bower.json b/bower.json
deleted file mode 100644
index e90a82a..0000000
--- a/bower.json
+++ /dev/null
@@ -1,32 +0,0 @@
-{
-  "name": "purescript-validation",
-  "homepage": "https://github.com/purescript/purescript-validation",
-  "license": "BSD-3-Clause",
-  "repository": {
-    "type": "git",
-    "url": "https://github.com/purescript/purescript-validation.git"
-  },
-  "ignore": [
-    "**/.*",
-    "bower_components",
-    "node_modules",
-    "output",
-    "test",
-    "bower.json",
-    "package.json"
-  ],
-  "dependencies": {
-    "purescript-bifunctors": "^6.0.0",
-    "purescript-control": "^6.0.0",
-    "purescript-either": "^6.0.0",
-    "purescript-foldable-traversable": "^6.0.0",
-    "purescript-newtype": "^5.0.0",
-    "purescript-prelude": "^6.0.0"
-  },
-  "devDependencies": {
-    "purescript-console": "^6.0.0",
-    "purescript-ordered-collections": "^3.0.0",
-    "purescript-psci-support": "^6.0.0",
-    "purescript-strings": "^6.0.0"
-  }
-}
diff --git a/examples/spago.yaml b/examples/spago.yaml
new file mode 100644
index 0000000..b7cb6dd
--- /dev/null
+++ b/examples/spago.yaml
@@ -0,0 +1,17 @@
+package:
+  name: validation-examples
+  build:
+    strict: true
+    pedanticPackages: true
+  run:
+    main: Semigroup
+  dependencies:
+    - arrays: ">=7.0.0 <8.0.0"
+    - bifunctors: ">=6.0.0 <7.0.0"
+    - console: ">=6.0.0 <7.0.0"
+    - effect: ">=4.0.0 <5.0.0"
+    - newtype: ">=5.0.0 <6.0.0"
+    - ordered-collections: ">=3.0.0 <4.0.0"
+    - prelude: ">=6.0.0 <7.0.0"
+    - strings: ">=6.0.0 <7.0.0"
+    - validation: "*"
diff --git a/package.json b/package.json
index e8e8435..c8cac5f 100644
--- a/package.json
+++ b/package.json
@@ -1,13 +1,16 @@
 {
   "private": true,
   "scripts": {
-    "clean": "rimraf output && rimraf .pulp-cache",
-    "build": "pulp build -- --censor-lib --strict",
-    "build:example": "pulp build --include examples"
+    "build": "spago build",
+    "build:example": "spago build -p validation-examples",
+    "example": "spago run -p validation-examples",
+    "format": "purs-tidy format-in-place src examples/src && oxfmt --write .",
+    "format:check": "purs-tidy check src examples/src && oxfmt --check ."
   },
   "devDependencies": {
-    "pulp": "16.0.0-0",
-    "purescript-psa": "^0.8.2",
-    "rimraf": "^3.0.2"
+    "oxfmt": "^0.73.0",
+    "purescript": "^0.15.16",
+    "purs-tidy": "^0.11.1",
+    "spago": "^1.0.5"
   }
 }
diff --git a/spago.yaml b/spago.yaml
new file mode 100644
index 0000000..15a83d7
--- /dev/null
+++ b/spago.yaml
@@ -0,0 +1,20 @@
+package:
+  name: validation
+  description: Applicative validation
+  build:
+    strict: true
+    pedanticPackages: true
+  publish:
+    version: 6.0.1
+    license: BSD-3-Clause
+    location:
+      githubOwner: purescript
+      githubRepo: purescript-validation
+  dependencies:
+    - bifunctors: ">=6.0.0 <7.0.0"
+    - control: ">=6.0.0 <7.0.0"
+    - either: ">=6.0.0 <7.0.0"
+    - foldable-traversable: ">=6.0.0 <7.0.0"
+    - newtype: ">=5.0.0 <6.0.0"
+    - prelude: ">=6.0.0 <7.0.0"
+workspace: {}

From 4e512914268b0066ccbe33b0c3501e454d337890 Mon Sep 17 00:00:00 2001
From: Thomas Honeyman <hello@thomashoneyman.com>
Date: Thu, 15 Oct 2026 18:05:35 +0000
Subject: [PATCH 2/7] Restore the example in a nested Spago package

---
 examples/{ => src}/Semigroup.purs | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
 rename examples/{ => src}/Semigroup.purs (98%)

diff --git a/examples/Semigroup.purs b/examples/src/Semigroup.purs
similarity index 98%
rename from examples/Semigroup.purs
rename to examples/src/Semigroup.purs
index b080eaa..403c653 100644
--- a/examples/Semigroup.purs
+++ b/examples/src/Semigroup.purs
@@ -8,9 +8,9 @@ import Data.Array.NonEmpty (NonEmptyArray)
 import Data.Array.NonEmpty as NonEmpty
 import Data.Bifunctor (bimap)
 import Data.Generic.Rep (class Generic)
-import Data.Generic.Rep.Eq (genericEq)
-import Data.Generic.Rep.Ord (genericCompare)
-import Data.Generic.Rep.Show (genericShow)
+import Data.Eq.Generic (genericEq)
+import Data.Ord.Generic (genericCompare)
+import Data.Show.Generic (genericShow)
 import Data.Map (Map)
 import Data.Map as Map
 import Data.Newtype (class Newtype, over2)

From dd6ff4a5212df08c3a407390c7969112537c7973 Mon Sep 17 00:00:00 2001
From: Thomas Honeyman <hello@thomashoneyman.com>
Date: Thu, 15 Oct 2026 18:05:46 +0000
Subject: [PATCH 3/7] Format PureScript and repository files

---
 CHANGELOG.md                       |  5 +++-
 examples/src/Semigroup.purs        | 44 +++++++++++++++---------------
 src/Data/Validation/Semigroup.purs |  2 +-
 src/Data/Validation/Semiring.purs  |  4 +--
 4 files changed, 29 insertions(+), 26 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 53caec3..61fede9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ Other improvements:
 ## [v6.0.0](https://github.com/purescript/purescript-validation/releases/tag/v6.0.0) - 2022-04-27
 
 Breaking changes:
+
 - Update project and deps to PureScript v0.15.0 (#37 by @JordanMartinez)
 - Drop deprecated `unV`; use `validation` instead (#38 by @JordanMartinez)
 
@@ -23,6 +24,7 @@ Other improvements:
 ## [v5.0.0](https://github.com/purescript/purescript-validation/releases/tag/v5.0.0) - 2021-02-26
 
 Breaking changes:
+
 - Added support for PureScript 0.14 and dropped support for all previous versions (#28)
 
 New features:
@@ -30,8 +32,9 @@ New features:
 Bugfixes:
 
 Other improvements:
+
 - Added detailed `Semigroup` validation examples (#17)
-- Added link to to Applicative Validation chapter in the PureScript book (#29) 
+- Added link to to Applicative Validation chapter in the PureScript book (#29)
 - Migrated CI to GitHub Actions and updated installation instructions to use Spago (#30)
 - Renamed `unV` to `validation` and deprecated `unV` (#33)
 - Added a changelog and pull request template (#34, #35)
diff --git a/examples/src/Semigroup.purs b/examples/src/Semigroup.purs
index 403c653..cff6bc8 100644
--- a/examples/src/Semigroup.purs
+++ b/examples/src/Semigroup.purs
@@ -2,20 +2,20 @@ module Semigroup where
 
 import Prelude
 
-import Effect (Effect)
-import Effect.Console (logShow)
 import Data.Array.NonEmpty (NonEmptyArray)
 import Data.Array.NonEmpty as NonEmpty
 import Data.Bifunctor (bimap)
-import Data.Generic.Rep (class Generic)
 import Data.Eq.Generic (genericEq)
-import Data.Ord.Generic (genericCompare)
-import Data.Show.Generic (genericShow)
+import Data.Generic.Rep (class Generic)
 import Data.Map (Map)
 import Data.Map as Map
 import Data.Newtype (class Newtype, over2)
+import Data.Ord.Generic (genericCompare)
+import Data.Show.Generic (genericShow)
 import Data.String (length, null, toLower, toUpper)
 import Data.Validation.Semigroup (V, invalid)
+import Effect (Effect)
+import Effect.Console (logShow)
 
 -- | `UnvalidatedFormData` represents the raw data we might receive from a form
 -- | before any validation has been performed.
@@ -46,7 +46,7 @@ type ValidatedFormData =
   }
 
 toString :: ValidatedFormData -> String
-toString { username: (Username u)} = "{ username: '" <> u <> "', password: <not shown> }"
+toString { username: (Username u) } = "{ username: '" <> u <> "', password: <not shown> }"
 
 -- | `ValidationError` represents the potential errors we might encounter during
 -- | the validation process.
@@ -166,10 +166,10 @@ instance showFormValidationErrors :: Show FormValidationErrors where
 -- | Otherwise, it returns the input wrapped in the `Username` newtype to
 -- | distinguish it from a normal, unvalidated `String`.
 validateUsername :: String -> V FormValidationErrors Username
-validateUsername input = 
+validateUsername input =
   bimap (FormValidationErrors <<< Map.singleton InvalidUsername) Username
-    $  validateNonEmpty input
-    *> validateMinimumLength 4 input
+    $ validateNonEmpty input
+        *> validateMinimumLength 4 input
 
 -- | This function validates that an input string conforms to our requirements
 -- | for a valid password. Namely, we require that the input be non-empty, at
@@ -185,11 +185,11 @@ validateUsername input =
 -- | Otherwise, it returns the input wrapped in the `Password` newtype to
 -- | distinguish it from a normal, unvalidated `String`.
 validatePassword :: String -> V FormValidationErrors Password
-validatePassword input = 
+validatePassword input =
   bimap (FormValidationErrors <<< Map.singleton InvalidPassword) Password
-    $  validateNonEmpty input
-    *> validateMinimumLength 6 input
-    *> validateMixedCase input
+    $ validateNonEmpty input
+        *> validateMinimumLength 6 input
+        *> validateMixedCase input
 
 -- | This function validates that an `UnvalidatedFormData` record contains both
 -- | a valid username and a valid password, per the requirements specified in
@@ -201,34 +201,34 @@ validatePassword input =
 -- |
 -- | Otherwise, it returns the validated fields in the `ValidatedFormData`
 -- | record specified above.
-validateForm 
-  :: UnvalidatedFormData 
+validateForm
+  :: UnvalidatedFormData
   -> V FormValidationErrors ValidatedFormData
-validateForm {username, password} = {username: _, password: _}
+validateForm { username, password } = { username: _, password: _ }
   <$> validateUsername username
   <*> validatePassword password
 
 -- | This is a form that will fail validation, since both fields are empty
 -- | strings.
 emptyUsernameAndPassword :: UnvalidatedFormData
-emptyUsernameAndPassword = {username: "", password: ""}
+emptyUsernameAndPassword = { username: "", password: "" }
 
 -- | This is a form that will fail validation, since both fields are too short.
 shortUsernameAndPassword :: UnvalidatedFormData
-shortUsernameAndPassword = {username: "foo", password: "bar"}
+shortUsernameAndPassword = { username: "foo", password: "bar" }
 
 -- | This is a form that will fail validation, since the password lowercase.
 lowerCasePassword :: UnvalidatedFormData
-lowerCasePassword = {username: "alice", password: "foobarbaz"}
+lowerCasePassword = { username: "alice", password: "foobarbaz" }
 
 -- | This is a form that will fail validation, since the password uppercase.
 upperCasePassword :: UnvalidatedFormData
-upperCasePassword = {username: "alice", password: "FOOBARBAZ"}
+upperCasePassword = { username: "alice", password: "FOOBARBAZ" }
 
 -- | This is a form that will pass validation, as it conforms to all the
 -- | requirements outlined in the validation functions above.
 goodForm :: UnvalidatedFormData
-goodForm = {username: "alice", password: "FooBarBaz"}
+goodForm = { username: "alice", password: "FooBarBaz" }
 
 -- | Run through all of the example forms and print the validation results to
 -- | the console.
@@ -253,4 +253,4 @@ main = do
   -- > pure ("{\"username\":\"alice\",\"password\":\"FooBarBaz\"}")
 
   where
-    printValidation = logShow <<< (map toString)
+  printValidation = logShow <<< (map toString)
diff --git a/src/Data/Validation/Semigroup.purs b/src/Data/Validation/Semigroup.purs
index 9e46aaa..2546851 100644
--- a/src/Data/Validation/Semigroup.purs
+++ b/src/Data/Validation/Semigroup.purs
@@ -20,9 +20,9 @@ import Data.Bifunctor (class Bifunctor)
 import Data.Either (Either(..))
 import Data.Eq (class Eq1)
 import Data.Foldable (class Foldable)
+import Data.Newtype (class Newtype)
 import Data.Ord (class Ord1)
 import Data.Traversable (class Traversable)
-import Data.Newtype (class Newtype)
 
 -- | The `V` functor, used for applicative validation
 -- |
diff --git a/src/Data/Validation/Semiring.purs b/src/Data/Validation/Semiring.purs
index 84c0b4e..1d01c46 100644
--- a/src/Data/Validation/Semiring.purs
+++ b/src/Data/Validation/Semiring.purs
@@ -19,9 +19,9 @@ import Data.Bifunctor (class Bifunctor)
 import Data.Either (Either(..))
 import Data.Eq (class Eq1)
 import Data.Foldable (class Foldable)
+import Data.Newtype (class Newtype)
 import Data.Ord (class Ord1)
 import Data.Traversable (class Traversable)
-import Data.Newtype (class Newtype)
 
 -- | The `V` functor, used for alternative validation
 -- |
@@ -87,7 +87,7 @@ derive newtype instance functorV :: Functor (V err)
 
 derive newtype instance bifunctorV :: Bifunctor V
 
-instance applyV :: Semiring err => Apply (V err)  where
+instance applyV :: Semiring err => Apply (V err) where
   apply (V (Left err1)) (V (Left err2)) = V (Left (err1 * err2))
   apply (V (Left err)) _ = V (Left err)
   apply _ (V (Left err)) = V (Left err)

From 395df2f906a1d85166f0eb0c12b8cfc0ef98fc3b Mon Sep 17 00:00:00 2001
From: Thomas Honeyman <hello@thomashoneyman.com>
Date: Thu, 15 Oct 2026 18:10:44 +0000
Subject: [PATCH 4/7] Credit the migration pull request

---
 CHANGELOG.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 61fede9..c55b5d7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,7 +6,7 @@ Notable changes to this project are documented in this file. The format is based
 
 Other improvements:
 
-- Migrate from Bower/Pulp to Spago, update CI and formatting, and restore the runnable example.
+- Migrate from Bower/Pulp to Spago, update CI and formatting, and restore the runnable example (#41 by @thomashoneyman).
 
 ## [v6.0.0](https://github.com/purescript/purescript-validation/releases/tag/v6.0.0) - 2022-04-27
 

From 8f6ff2092f2dbc6785673c15e8c9cdac0f89f9c7 Mon Sep 17 00:00:00 2001
From: Thomas Honeyman <hello@thomashoneyman.com>
Date: Thu, 15 Oct 2026 21:26:22 +0000
Subject: [PATCH 5/7] Prepare changelog release date and unreleased section

---
 CHANGELOG.md | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c55b5d7..f3be4df 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,17 @@
 
 Notable changes to this project are documented in this file. The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [v6.0.1](https://github.com/purescript/purescript-validation/releases/tag/v6.0.1)
+## [Unreleased]
+
+Breaking changes:
+
+New features:
+
+Bugfixes:
+
+Other improvements:
+
+## [v6.0.1](https://github.com/purescript/purescript-validation/releases/tag/v6.0.1) - 2026-10-17
 
 Other improvements:
 

From a858046da3f136fe9f0cd5a73cee5f602ae7489e Mon Sep 17 00:00:00 2001
From: Thomas Honeyman <hello@thomashoneyman.com>
Date: Sat, 17 Oct 2026 13:05:06 +0000
Subject: [PATCH 6/7] Use explicit case expressions for validation branches

---
 src/Data/Validation/Semigroup.purs | 19 +++++++++++--------
 src/Data/Validation/Semiring.purs  | 26 +++++++++++++++-----------
 2 files changed, 26 insertions(+), 19 deletions(-)

diff --git a/src/Data/Validation/Semigroup.purs b/src/Data/Validation/Semigroup.purs
index 2546851..a2cb149 100644
--- a/src/Data/Validation/Semigroup.purs
+++ b/src/Data/Validation/Semigroup.purs
@@ -46,8 +46,9 @@ derive instance newtypeV :: Newtype (V err result) _
 -- | applied to the first function, if the validation succeeded the inner value
 -- | is applied to the second function.
 validation :: forall err result r. (err -> r) -> (result -> r) -> V err result -> r
-validation f _ (V (Left err)) = f err
-validation _ g (V (Right result)) = g result
+validation f g (V value) = case value of
+  Left err -> f err
+  Right result -> g result
 
 -- | Fail with a validation error.
 invalid :: forall err result. err -> V err result
@@ -55,8 +56,9 @@ invalid = V <<< Left
 
 -- | Test whether validation was successful or not.
 isValid :: forall err result. V err result -> Boolean
-isValid (V (Right _)) = true
-isValid _ = false
+isValid = case _ of
+  V (Right _) -> true
+  _ -> false
 
 toEither :: forall err result. V err result -> Either err result
 toEither (V e) = e
@@ -87,10 +89,11 @@ derive newtype instance functorV :: Functor (V err)
 derive newtype instance bifunctorV :: Bifunctor V
 
 instance applyV :: Semigroup err => Apply (V err) where
-  apply (V (Left err1)) (V (Left err2)) = V (Left (err1 <> err2))
-  apply (V (Left err)) _ = V (Left err)
-  apply _ (V (Left err)) = V (Left err)
-  apply (V (Right f)) (V (Right x)) = V (Right (f x))
+  apply left right = case left, right of
+    V (Left err1), V (Left err2) -> V (Left (err1 <> err2))
+    V (Left err), _ -> V (Left err)
+    _, V (Left err) -> V (Left err)
+    V (Right f), V (Right x) -> V (Right (f x))
 
 instance applicativeV :: Semigroup err => Applicative (V err) where
   pure = V <<< Right
diff --git a/src/Data/Validation/Semiring.purs b/src/Data/Validation/Semiring.purs
index 1d01c46..366bbbf 100644
--- a/src/Data/Validation/Semiring.purs
+++ b/src/Data/Validation/Semiring.purs
@@ -47,8 +47,9 @@ derive instance newtypeV :: Newtype (V err result) _
 -- | applied to the first function, if the validation succeeded the inner value
 -- | is applied to the second function.
 validation :: forall err result r. (err -> r) -> (result -> r) -> V err result -> r
-validation f _ (V (Left err)) = f err
-validation _ g (V (Right result)) = g result
+validation f g (V value) = case value of
+  Left err -> f err
+  Right result -> g result
 
 -- | Fail with a validation error.
 invalid :: forall err result. err -> V err result
@@ -56,8 +57,9 @@ invalid = V <<< Left
 
 -- | Test whether validation was successful or not.
 isValid :: forall err result. V err result -> Boolean
-isValid (V (Right _)) = true
-isValid _ = false
+isValid = case _ of
+  V (Right _) -> true
+  _ -> false
 
 toEither :: forall err result. V err result -> Either err result
 toEither (V e) = e
@@ -88,10 +90,11 @@ derive newtype instance functorV :: Functor (V err)
 derive newtype instance bifunctorV :: Bifunctor V
 
 instance applyV :: Semiring err => Apply (V err) where
-  apply (V (Left err1)) (V (Left err2)) = V (Left (err1 * err2))
-  apply (V (Left err)) _ = V (Left err)
-  apply _ (V (Left err)) = V (Left err)
-  apply (V (Right f)) (V (Right x)) = V (Right (f x))
+  apply left right = case left, right of
+    V (Left err1), V (Left err2) -> V (Left (err1 * err2))
+    V (Left err), _ -> V (Left err)
+    _, V (Left err) -> V (Left err)
+    V (Right f), V (Right x) -> V (Right (f x))
 
 instance applicativeV :: Semiring err => Applicative (V err) where
   pure = V <<< Right
@@ -103,9 +106,10 @@ instance monoidV :: (Semiring err, Monoid a) => Monoid (V err a) where
   mempty = pure mempty
 
 instance altV :: Semiring err => Alt (V err) where
-  alt (V (Left err1)) (V (Left err2)) = V (Left (err1 + err2))
-  alt (V (Left _)) a = a
-  alt (V (Right a)) _ = V (Right a)
+  alt left right = case left, right of
+    V (Left err1), V (Left err2) -> V (Left (err1 + err2))
+    V (Left _), a -> a
+    V (Right a), _ -> V (Right a)
 
 instance plusV :: Semiring err => Plus (V err) where
   empty = V (Left zero)

From aadb7d74b77210ba9abb9a19e7be055a2af45f38 Mon Sep 17 00:00:00 2001
From: Thomas Honeyman <hello@thomashoneyman.com>
Date: Sat, 17 Oct 2026 16:29:24 +0000
Subject: [PATCH 7/7] Correct release changelog coverage and Unreleased link

---
 CHANGELOG.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f3be4df..5853660 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,7 +2,7 @@
 
 Notable changes to this project are documented in this file. The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/) and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [Unreleased]
+## [Unreleased](https://github.com/purescript/purescript-validation/compare/v6.0.1...HEAD)
 
 Breaking changes:
 
@@ -17,6 +17,7 @@ Other improvements:
 Other improvements:
 
 - Migrate from Bower/Pulp to Spago, update CI and formatting, and restore the runnable example (#41 by @thomashoneyman).
+- Use explicit case expressions for validation branches (#41 by @thomashoneyman).
 
 ## [v6.0.0](https://github.com/purescript/purescript-validation/releases/tag/v6.0.0) - 2022-04-27