More flexible insert builder

Sources/StructuredQueries/Macros.swift

@@ -91,7 +91,7 @@ public macro Ephemeral() =
 /// or common table expression.
 @attached(
   extension,
-  conformances: QueryRepresentable,
+  conformances: _Selection,
   names: named(Columns),
   named(init(decoder:))
 )

Sources/StructuredQueriesCore/Internal/Deprecations.swift

@@ -65,7 +65,7 @@ extension Table {
   public static func insert(
     or conflictResolution: ConflictResolution? = nil,
     _ columns: (TableColumns) -> TableColumns = { $0 },
-    @InsertValuesBuilder<Self> values: () -> [Self],
+    @InsertValuesBuilder<Self> values: () -> [[QueryFragment]],
     onConflict updates: ((inout Updates<Self>) -> Void)?
   ) -> InsertOf<Self> {
     insert(or: conflictResolution, columns, values: values, onConflictDoUpdate: updates)
@@ -75,8 +75,8 @@ extension Table {
   public static func insert<V1, each V2>(
     or conflictResolution: ConflictResolution? = nil,
     _ columns: (TableColumns) -> (TableColumn<Self, V1>, repeat TableColumn<Self, each V2>),
-    @InsertValuesBuilder<(V1.QueryOutput, repeat (each V2).QueryOutput)>
-    values: () -> [(V1.QueryOutput, repeat (each V2).QueryOutput)],
+    @InsertValuesBuilder<(V1, repeat each V2)>
+    values: () -> [[QueryFragment]],
     onConflict updates: ((inout Updates<Self>) -> Void)?
   ) -> InsertOf<Self> {
     insert(or: conflictResolution, columns, values: values, onConflictDoUpdate: updates)

Sources/StructuredQueriesCore/Seeds.swift

@@ -67,7 +67,7 @@ public struct Seeds: Sequence {
   /// [SharingGRDB]: https://github.com/pointfreeco/sharing-grdb
   ///
   /// - Parameter build: A result builder closure that prepares statements to insert every built row.
-  public init(@InsertValuesBuilder<any Table> _ build: () -> [any Table]) {
+  public init(@SeedsBuilder _ build: () -> [any Table]) {
     self.seeds = build()
   }
 
@@ -103,3 +103,46 @@ public struct Seeds: Sequence {
     }
   }
 }
+
+@resultBuilder
+public enum SeedsBuilder {
+  public static func buildArray(_ components: [[any Table]]) -> [any Table] {
+    components.flatMap(\.self)
+  }
+
+  public static func buildBlock(_ components: [any Table]) -> [any Table] {
+    components
+  }
+
+  public static func buildEither(first component: [any Table]) -> [any Table] {
+    component
+  }
+
+  public static func buildEither(second component: [any Table]) -> [any Table] {
+    component
+  }
+
+  public static func buildExpression(_ expression: some Table) -> [any Table] {
+    [expression]
+  }
+
+  public static func buildExpression(_ expression: [any Table]) -> [any Table] {
+    expression
+  }
+
+  public static func buildLimitedAvailability(_ component: [any Table]) -> [any Table] {
+    component
+  }
+
+  public static func buildOptional(_ component: [any Table]?) -> [any Table] {
+    component ?? []
+  }
+
+  public static func buildPartialBlock(first: [any Table]) -> [any Table] {
+    first
+  }
+
+  public static func buildPartialBlock(accumulated: [any Table], next: [any Table]) -> [any Table] {
+    accumulated + next
+  }
+}