From d7f73e27ffe2aa16e2b7bb00ef00ab33c1f798dd Mon Sep 17 00:00:00 2001
From: Stephen Celis <stephen@stephencelis.com>
Date: Mon, 1 Sep 2025 10:23:03 -0700
Subject: [PATCH 1/6] Support for StructuredQueries' `@DatabaseFunction` macro

See https://github.com/pointfreeco/swift-structured-queries/pull/151 for
more details.
---
 Package.resolved                              |   6 +-
 Package.swift                                 |   4 +-
 .../StructuredQueriesGRDB.swift               |   1 +
 .../CustomFunctions.swift                     | 122 ++++++++++++++++++
 .../Internal/Exports.swift                    |   1 +
 5 files changed, 130 insertions(+), 4 deletions(-)
 create mode 100644 Sources/StructuredQueriesGRDBCore/CustomFunctions.swift

diff --git a/Package.resolved b/Package.resolved
index a4e00c4e..2894e8d4 100644
--- a/Package.resolved
+++ b/Package.resolved
@@ -1,5 +1,5 @@
 {
-  "originHash" : "d87ac3bfcdef05674d1d54c62277ab77a7f1a74d2b106a3e0a8eb5567e2ff1ed",
+  "originHash" : "1932408fc9a59e0236b9a7e2c6038962acd4027e2acea33c798d3e20a50fbf02",
   "pins" : [
     {
       "identity" : "combine-schedulers",
@@ -123,8 +123,8 @@
       "kind" : "remoteSourceControl",
       "location" : "https://github.com/pointfreeco/swift-structured-queries",
       "state" : {
-        "revision" : "b5b5a9ed9ff321f43a02f07394f2831eba5e11f2",
-        "version" : "0.13.0"
+        "branch" : "custom-functions",
+        "revision" : "038b40be3b89d1794854b48bfc942fd09811885e"
       }
     },
     {
diff --git a/Package.swift b/Package.swift
index d389be9e..4b2186f0 100644
--- a/Package.swift
+++ b/Package.swift
@@ -39,7 +39,7 @@ let package = Package(
     .package(url: "https://github.com/pointfreeco/xctest-dynamic-overlay", from: "1.5.0"),
     .package(url: "https://github.com/pointfreeco/swift-sharing", from: "2.3.0"),
     .package(url: "https://github.com/pointfreeco/swift-snapshot-testing", from: "1.18.4"),
-    .package(url: "https://github.com/pointfreeco/swift-structured-queries", from: "0.13.0"),
+    .package(url: "https://github.com/pointfreeco/swift-structured-queries", branch: "custom-functions"),
   ],
   targets: [
     .target(
@@ -82,6 +82,7 @@ let package = Package(
         .product(name: "Dependencies", package: "swift-dependencies"),
         .product(name: "IssueReporting", package: "xctest-dynamic-overlay"),
         .product(name: "StructuredQueriesCore", package: "swift-structured-queries"),
+        .product(name: "StructuredQueriesSQLiteCore", package: "swift-structured-queries"),
       ]
     ),
     .target(
@@ -89,6 +90,7 @@ let package = Package(
       dependencies: [
         "StructuredQueriesGRDBCore",
         .product(name: "StructuredQueries", package: "swift-structured-queries"),
+        .product(name: "StructuredQueriesSQLite", package: "swift-structured-queries"),
       ]
     ),
     .testTarget(
diff --git a/Sources/StructuredQueriesGRDB/StructuredQueriesGRDB.swift b/Sources/StructuredQueriesGRDB/StructuredQueriesGRDB.swift
index 99a11a9d..047e9bfe 100644
--- a/Sources/StructuredQueriesGRDB/StructuredQueriesGRDB.swift
+++ b/Sources/StructuredQueriesGRDB/StructuredQueriesGRDB.swift
@@ -1,2 +1,3 @@
 @_exported import StructuredQueries
+@_exported import StructuredQueriesSQLite
 @_exported import StructuredQueriesGRDBCore
diff --git a/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift b/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift
new file mode 100644
index 00000000..46a3e7aa
--- /dev/null
+++ b/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift
@@ -0,0 +1,122 @@
+import GRDB
+import GRDBSQLite
+import Foundation
+
+extension ScalarDatabaseFunction {
+  /// Adds a user-defined `@DatabaseFunction` to a connection.
+  ///
+  /// - Parameter db: A database connection.
+  public func install(db: Database) {
+    let db = db.sqliteConnection
+    let box = Unmanaged.passRetained(ScalarDatabaseFunctionBox(self)).toOpaque()
+    sqlite3_create_function_v2(
+      db,
+      name,
+      argumentCount,
+      textEncoding,
+      box,
+      { context, argumentCount, arguments in
+        Unmanaged<ScalarDatabaseFunctionBox>
+          .fromOpaque(sqlite3_user_data(context))
+          .takeUnretainedValue()
+          .function
+          .invoke([QueryBinding](argumentCount: argumentCount, arguments: arguments))
+          .result(db: context)
+      },
+      nil,
+      nil,
+      { context in
+        guard let context else { return }
+        Unmanaged<ScalarDatabaseFunctionBox>.fromOpaque(context).release()
+      }
+    )
+  }
+
+  /// Deletes a user-defined `@DatabaseFunction` from a connection.
+  ///
+  /// - Parameter db: A database connection.
+  public func uninstall(db: Database) {
+    let db = db.sqliteConnection
+    sqlite3_create_function_v2(
+      db,
+      name,
+      argumentCount,
+      textEncoding,
+      nil,
+      nil,
+      nil,
+      nil,
+      nil
+    )
+  }
+
+  private var argumentCount: Int32 {
+    Int32(argumentCount ?? -1)
+  }
+
+  private var textEncoding: Int32 {
+    SQLITE_UTF8 | (isDeterministic ? SQLITE_DETERMINISTIC : 0)
+  }
+}
+
+private final class ScalarDatabaseFunctionBox {
+  let function: any ScalarDatabaseFunction
+  init(_ function: some ScalarDatabaseFunction) {
+    self.function = function
+  }
+}
+
+extension [QueryBinding] {
+  fileprivate init(argumentCount: Int32, arguments: UnsafeMutablePointer<OpaquePointer?>?) {
+    self = (0..<argumentCount).map { offset in
+      let value = arguments?[Int(offset)]
+      switch sqlite3_value_type(value) {
+      case SQLITE_BLOB:
+        if let blob = sqlite3_value_blob(value) {
+          let count = Int(sqlite3_value_bytes(value))
+          let buffer = UnsafeRawBufferPointer(start: blob, count: count)
+          return .blob([UInt8](buffer))
+        } else {
+          return .blob([])
+        }
+      case SQLITE_FLOAT:
+        return .double(sqlite3_value_double(value))
+      case SQLITE_INTEGER:
+        return .int(sqlite3_value_int64(value))
+      case SQLITE_NULL:
+        return .null
+      case SQLITE_TEXT:
+        return .text(String(cString: UnsafePointer(sqlite3_value_text(value))))
+      default:
+        return .invalid(UnknownType())
+      }
+    }
+  }
+
+  private struct UnknownType: Error {}
+}
+
+extension QueryBinding {
+  fileprivate func result(db: OpaquePointer?) {
+    switch self {
+    case .blob(let value):
+      sqlite3_result_blob(db, Array(value), Int32(value.count), SQLITE_TRANSIENT)
+    case .double(let value):
+      sqlite3_result_double(db, value)
+    case .date(let value):
+      sqlite3_result_text(db, value.iso8601String, -1, SQLITE_TRANSIENT)
+    case .int(let value):
+      sqlite3_result_int64(db, value)
+    case .null:
+      sqlite3_result_null(db)
+    case .text(let value):
+      sqlite3_result_text(db, value, -1, SQLITE_TRANSIENT)
+    case .uuid(let value):
+      sqlite3_result_text(db, value.uuidString.lowercased(), -1, SQLITE_TRANSIENT)
+    case .invalid(let error):
+      sqlite3_result_error(db, error.underlyingError.localizedDescription, -1)
+    }
+  }
+}
+
+let SQLITE_TRANSIENT = unsafeBitCast(-1, to: sqlite3_destructor_type.self)
diff --git a/Sources/StructuredQueriesGRDBCore/Internal/Exports.swift b/Sources/StructuredQueriesGRDBCore/Internal/Exports.swift
index 320bdbac..e29fce7e 100644
--- a/Sources/StructuredQueriesGRDBCore/Internal/Exports.swift
+++ b/Sources/StructuredQueriesGRDBCore/Internal/Exports.swift
@@ -1 +1,2 @@
 @_exported import StructuredQueriesCore
+@_exported import StructuredQueriesSQLiteCore

From 905899c91fddfb9e7e386dfff7113bcfc9c5deb5 Mon Sep 17 00:00:00 2001
From: Stephen Celis <stephen@stephencelis.com>
Date: Mon, 1 Sep 2025 10:56:42 -0700
Subject: [PATCH 2/6] wip

---
 .../CustomFunctions.swift                     | 42 +++++++++----------
 1 file changed, 21 insertions(+), 21 deletions(-)

diff --git a/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift b/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift
index 46a3e7aa..0e946823 100644
--- a/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift
+++ b/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift
@@ -2,18 +2,17 @@ import GRDB
 import GRDBSQLite
 import Foundation
 
-extension ScalarDatabaseFunction {
+extension Database {
   /// Adds a user-defined `@DatabaseFunction` to a connection.
   ///
-  /// - Parameter db: A database connection.
-  public func install(db: Database) {
-    let db = db.sqliteConnection
-    let box = Unmanaged.passRetained(ScalarDatabaseFunctionBox(self)).toOpaque()
+  /// - Parameter function: A database function to add.
+  public func add(function: some ScalarDatabaseFunction) {
+    let box = Unmanaged.passRetained(ScalarDatabaseFunctionBox(function)).toOpaque()
     sqlite3_create_function_v2(
-      db,
-      name,
-      argumentCount,
-      textEncoding,
+      sqliteConnection,
+      function.name,
+      function.argumentCount,
+      function.textEncoding,
       box,
       { context, argumentCount, arguments in
         Unmanaged<ScalarDatabaseFunctionBox>
@@ -25,23 +24,22 @@ extension ScalarDatabaseFunction {
       },
       nil,
       nil,
-      { context in
-        guard let context else { return }
-        Unmanaged<ScalarDatabaseFunctionBox>.fromOpaque(context).release()
+      { box in
+        guard let box else { return }
+        Unmanaged<ScalarDatabaseFunctionBox>.fromOpaque(box).release()
       }
     )
   }
 
   /// Deletes a user-defined `@DatabaseFunction` from a connection.
   ///
-  /// - Parameter db: A database connection.
-  public func uninstall(db: Database) {
-    let db = db.sqliteConnection
+  /// - Parameter function: A database function to delete.
+  public func remove(function: some ScalarDatabaseFunction) {
     sqlite3_create_function_v2(
-      db,
-      name,
-      argumentCount,
-      textEncoding,
+      sqliteConnection,
+      function.name,
+      function.argumentCount,
+      function.textEncoding,
       nil,
       nil,
       nil,
@@ -49,12 +47,14 @@ extension ScalarDatabaseFunction {
       nil
     )
   }
+}
 
-  private var argumentCount: Int32 {
+extension ScalarDatabaseFunction {
+  fileprivate var argumentCount: Int32 {
     Int32(argumentCount ?? -1)
   }
 
-  private var textEncoding: Int32 {
+  fileprivate var textEncoding: Int32 {
     SQLITE_UTF8 | (isDeterministic ? SQLITE_DETERMINISTIC : 0)
   }
 }

From b1d05925570dcb830db66f029f7b8730e7dc4220 Mon Sep 17 00:00:00 2001
From: Stephen Celis <stephen@stephencelis.com>
Date: Mon, 1 Sep 2025 10:57:46 -0700
Subject: [PATCH 3/6] wip

---
 Sources/StructuredQueriesGRDBCore/CustomFunctions.swift | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift b/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift
index 0e946823..38c7b7a5 100644
--- a/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift
+++ b/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift
@@ -7,13 +7,12 @@ extension Database {
   ///
   /// - Parameter function: A database function to add.
   public func add(function: some ScalarDatabaseFunction) {
-    let box = Unmanaged.passRetained(ScalarDatabaseFunctionBox(function)).toOpaque()
     sqlite3_create_function_v2(
       sqliteConnection,
       function.name,
       function.argumentCount,
       function.textEncoding,
-      box,
+      Unmanaged.passRetained(ScalarDatabaseFunctionBox(function)).toOpaque(),
       { context, argumentCount, arguments in
         Unmanaged<ScalarDatabaseFunctionBox>
           .fromOpaque(sqlite3_user_data(context))

From af10454f028ed690527c4ae0e6eb5dc72b7a9d97 Mon Sep 17 00:00:00 2001
From: Stephen Celis <stephen@stephencelis.com>
Date: Mon, 1 Sep 2025 11:02:23 -0700
Subject: [PATCH 4/6] test

---
 .../CustomFunctionTests.swift                 | 32 +++++++++++++++++++
 1 file changed, 32 insertions(+)
 create mode 100644 Tests/StructuredQueriesGRDBTests/CustomFunctionTests.swift

diff --git a/Tests/StructuredQueriesGRDBTests/CustomFunctionTests.swift b/Tests/StructuredQueriesGRDBTests/CustomFunctionTests.swift
new file mode 100644
index 00000000..003e3370
--- /dev/null
+++ b/Tests/StructuredQueriesGRDBTests/CustomFunctionTests.swift
@@ -0,0 +1,32 @@
+import Foundation
+import GRDB
+import StructuredQueriesGRDB
+import Testing
+
+@Suite struct CustomFunctionsTests {
+  @DatabaseFunction func customDate() -> Date {
+    Date(timeIntervalSinceReferenceDate: 0)
+  }
+
+  @Test func basics() throws {
+    var configuration = Configuration()
+    configuration.prepareDatabase { db in
+      db.add(function: $customDate)
+    }
+    let database = try DatabaseQueue(configuration: configuration)
+    let date = try database.read { db in
+      try Values($customDate())
+        .fetchOne(db)
+    }
+    #expect(date?.timeIntervalSinceReferenceDate == 0)
+
+    try database.write { db in
+      db.remove(function: $customDate)
+    }
+    #expect(throws: (any Error).self) {
+      try database.read { db in
+        _ = try Values($customDate()).fetchOne(db)
+      }
+    }
+  }
+}

From bbb0323afc33d02afbcb4fb9d56b78f060325527 Mon Sep 17 00:00:00 2001
From: Stephen Celis <stephen@stephencelis.com>
Date: Mon, 1 Sep 2025 11:02:58 -0700
Subject: [PATCH 5/6] wip

---
 Sources/StructuredQueriesGRDBCore/CustomFunctions.swift | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift b/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift
index 38c7b7a5..2b93a3f2 100644
--- a/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift
+++ b/Sources/StructuredQueriesGRDBCore/CustomFunctions.swift
@@ -1,6 +1,6 @@
+import Foundation
 import GRDB
 import GRDBSQLite
-import Foundation
 
 extension Database {
   /// Adds a user-defined `@DatabaseFunction` to a connection.

From b3e837114dd056c1f48065b451702f565c1d9d79 Mon Sep 17 00:00:00 2001
From: Stephen Celis <stephen@stephencelis.com>
Date: Mon, 1 Sep 2025 15:25:36 -0700
Subject: [PATCH 6/6] wip

---
 .../xcshareddata/swiftpm/Package.resolved                   | 4 ++--
 Package.resolved                                            | 6 +++---
 Package.swift                                               | 2 +-
 3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/Examples/Examples.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved b/Examples/Examples.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved
index c35f7919..bf1fd701 100644
--- a/Examples/Examples.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved
+++ b/Examples/Examples.xcodeproj/project.xcworkspace/xcshareddata/swiftpm/Package.resolved
@@ -123,8 +123,8 @@
       "kind" : "remoteSourceControl",
       "location" : "https://github.com/pointfreeco/swift-structured-queries",
       "state" : {
-        "revision" : "b5b5a9ed9ff321f43a02f07394f2831eba5e11f2",
-        "version" : "0.13.0"
+        "revision" : "e53cd5c87b31eeba77a801eec9a7e82c6d7faaab",
+        "version" : "0.15.0"
       }
     },
     {
diff --git a/Package.resolved b/Package.resolved
index 2894e8d4..a28c3596 100644
--- a/Package.resolved
+++ b/Package.resolved
@@ -1,5 +1,5 @@
 {
-  "originHash" : "1932408fc9a59e0236b9a7e2c6038962acd4027e2acea33c798d3e20a50fbf02",
+  "originHash" : "96fc55dd49af697ce0e0bf306c46a68e5c589a1cabb04749621327771c159fb5",
   "pins" : [
     {
       "identity" : "combine-schedulers",
@@ -123,8 +123,8 @@
       "kind" : "remoteSourceControl",
       "location" : "https://github.com/pointfreeco/swift-structured-queries",
       "state" : {
-        "branch" : "custom-functions",
-        "revision" : "038b40be3b89d1794854b48bfc942fd09811885e"
+        "revision" : "e53cd5c87b31eeba77a801eec9a7e82c6d7faaab",
+        "version" : "0.15.0"
       }
     },
     {
diff --git a/Package.swift b/Package.swift
index 4b2186f0..41c5f830 100644
--- a/Package.swift
+++ b/Package.swift
@@ -39,7 +39,7 @@ let package = Package(
     .package(url: "https://github.com/pointfreeco/xctest-dynamic-overlay", from: "1.5.0"),
     .package(url: "https://github.com/pointfreeco/swift-sharing", from: "2.3.0"),
     .package(url: "https://github.com/pointfreeco/swift-snapshot-testing", from: "1.18.4"),
-    .package(url: "https://github.com/pointfreeco/swift-structured-queries", branch: "custom-functions"),
+    .package(url: "https://github.com/pointfreeco/swift-structured-queries", from: "0.15.0"),
   ],
   targets: [
     .target(