[base] Add an id variant of the string concatenator repeated

Also, add some unit tests for the new repeateds

Base/src/main/scala/typeclass/Repeat.scala

@@ -86,6 +86,20 @@ trait BiRepeated[Expr[_], A, Z]
 
 /** Predefined implicit implementations of Repeated */
 object Repeated extends VersionSpecificRepeated with LowPrioRepeated {
+	private def apply[A, Acc, Z](
+		initFn: () => Acc,
+		appendFn: (Acc, A) => Acc,
+		resultFn: Acc => Z,
+	): Repeated[A, Z] = {
+		type Acc2 = Acc
+		new Repeated[A, Z] {
+			type Acc = Acc2
+			def init():Acc = initFn()
+			def append(acc:Acc, elem:A):Acc = appendFn(acc, elem)
+			def result(acc:Acc):Z = resultFn(acc)
+		}
+	}
+
 	/**
 	 * Repeated units results in a unit
 	 */
@@ -124,6 +138,14 @@ object Repeated extends VersionSpecificRepeated with LowPrioRepeated {
 		}
 		new RepeatedCodepoint()
 	}
+
+	def idConcatenateString:Repeated[String, String] = {
+		Repeated.apply(
+			() => new StringBuilder,
+			(acc:StringBuilder, elem:String) => acc ++= elem,
+			(acc:StringBuilder) => acc.toString,
+		)
+	}
 }
 
 private[typeclass] trait LowPrioRepeated {

Base/src/test/scala-3/typeclass/VersonSpecificRepeatedTest.scala

@@ -0,0 +1,28 @@
+package name.rayrobdod.stringContextParserCombinator
+package typeclass
+package repeated
+
+import scala.quoted.*
+import munit.Location
+
+final class QuotedConcatenateStringTest extends munit.FunSuite {
+	inline def assertParseSuccess(
+		inline sc: StringContext,
+		inline args: Any*)(
+		expecting:String)(
+		using loc:Location
+	):Unit = ${
+		QuotedConcatenateStringTestImpls.assertParseSuccessImpl(
+			'this, 'sc, 'args, 'expecting, 'loc)
+	}
+
+	test ("0") {
+		assertParseSuccess(StringContext(""))("")
+	}
+	test ("1") {
+		assertParseSuccess(StringContext("ab"))("ab")
+	}
+	test ("many") {
+		assertParseSuccess(StringContext("ab", "cd", "ef"), "12", "34")("ab12cd34ef")
+	}
+}

Base/src/test/scala-3/typeclass/VersonSpecificRepeatedTestImpls.scala

@@ -0,0 +1,30 @@
+package name.rayrobdod.stringContextParserCombinator
+package typeclass
+package repeated
+
+import scala.quoted.*
+import munit.Location
+import Interpolator.{charWhere, ofType, end}
+
+object QuotedConcatenateStringTestImpls {
+	def assertParseSuccessImpl(
+		self: Expr[munit.FunSuite],
+		sc: Expr[StringContext],
+		args: Expr[Seq[Any]],
+		expecting: Expr[String],
+		loc: Expr[Location])(
+		using Quotes
+	):Expr[Unit] = {
+
+		val dut = (charWhere(_ => true).repeat(1).mapToExpr orElse ofType[String])
+			.repeat()(using Repeated.quotedConcatenateString)
+			.andThen(end)
+
+		val actual = dut.interpolate(sc, args)
+
+		'{
+			given Location = ${loc}
+			$self.assertEquals($actual, $expecting)
+		}
+	}
+}

Base/src/test/scala/typeclass/RepeatedTest.scala

@@ -0,0 +1,21 @@
+package name.rayrobdod.stringContextParserCombinator
+package typeclass
+package repeated
+
+import Interpolator.idInterpolators.{charWhere, ofType, end}
+
+final class IdConcatenateString extends BaseInterpolatorSuite {
+	val dut = (charWhere(_ => true).repeat(1) orElse ofType[String])
+		.repeat()(using Repeated.idConcatenateString)
+		.andThen(end)
+
+	test ("0") {
+		assertParseSuccess(dut, ("" :: Nil, Nil), "")
+	}
+	test ("1") {
+		assertParseSuccess(dut, ("ab" :: Nil, Nil), "ab")
+	}
+	test ("many") {
+		assertParseSuccess(dut, ("ab" :: "cd" :: "ef" :: Nil, "12" :: "34" :: Nil), "ab12cd34ef")
+	}
+}