Scala prompt templating

examples/scala/src/main/scala/com/xebia/functional/xef/scala/auto/SynopsisReview.scala

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+package com.xebia.functional.xef.scala.auto
+
+import com.xebia.functional.xef.scala.auto.*
+import com.xebia.functional.xef.scala.prompt.*
+import io.circe.Decoder
+
+final case class Play(title: String, era: String) derives PromptTemplate, Decoder, ScalaSerialDescriptor
+
+final case class Synopsis(summary: String) derives PromptTemplate, Decoder, ScalaSerialDescriptor
+
+final case class Review(review: String) derives PromptTemplate, Decoder, ScalaSerialDescriptor
+
+final case class Score(score: Double) derives PromptTemplate, Decoder, ScalaSerialDescriptor
+
+@main def runSynopsisReview: Unit = {
+  def synopsisTemplate(play: Play): String =
+    s"""
+       |You are a playwright. Given the title of play and the era it is set in, it is your job to write a synopsis for that title.
+       |
+       |Title: ${play.title}.
+       |Era: ${play.era}.
+       |Playwright: This is a synopsis for the above play:
+      """.stripMargin
+
+  def reviewTemplate(synopsis: Synopsis): String =
+    s"""
+       |You are a play critic from the New York Times. Given the synopsis of play, it is your job to write a review for that play.
+       |
+       |Play Synopsis: ${synopsis.summary}.
+       |Review from a New York Times play critic of the above play:
+    """.stripMargin
+
+  def scoreTemplate(review: Review): String =
+    s"""
+       |You are an independent play critic scoring the best plays of the year.
+       |Given the review of the play, it is your job to score this play.
+       |
+       |Play Review: ${review.review}.
+       |Score the above play from 0 to 10:
+    """.stripMargin
+
+  val playScore = PromptTemplate[Play](Play("The power of Zuluastral", "Modern Era"))
+    .chain[Synopsis](play => synopsisTemplate(play))
+    .chain[Review](synopsis => reviewTemplate(synopsis))
+    .chain[Score](review => scoreTemplate(review))
+  println(s"Score (0 to 10): " + playScore.score)
+}

scala/src/main/scala/com/xebia/functional/xef/scala/prompt/PromptTemplate.scala

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+package com.xebia.functional.xef.scala.prompt
+
+import com.xebia.functional.xef.scala.auto.*
+import io.circe.Decoder
+
+trait PromptTemplate[A] {
+
+  def chain(template: String): A
+
+  extension (a: A) {
+    def chain[B: ScalaSerialDescriptor: Decoder](template: A => String): B =
+      ai(prompt[B](template(a)))
+  }
+}
+
+object PromptTemplate:
+
+  def apply[A](instance: A): A = instance
+
+  inline final def derived[A: ScalaSerialDescriptor: Decoder]: PromptTemplate[A] = new PromptTemplate[A]:
+
+    def chain(template: String): A = ai(prompt[A](template))