detect tactical motifs in games

Similar to what the puzzle tagger does
https://github.com/ornicar/lichess-puzzler/blob/master/tagger/cook.py

build.sbt

@@ -54,6 +54,13 @@ lazy val playJson: Project = Project("playJson", file("playJson"))
   )
   .dependsOn(scalachess)
 
+lazy val motif: Project = Project("motif", file("motif"))
+  .settings(
+    commonSettings,
+    name := "scalachess-motif"
+  )
+  .dependsOn(scalachess)
+
 lazy val bench = project
   .enablePlugins(JmhPlugin)
   .settings(commonSettings, scalacOptions -= "-Wunused:all", name := "bench")

motif/README.md

@@ -0,0 +1,2 @@
+Detect tactical motifs in games.
+Similar to what [the puzzle tagger](https://github.com/ornicar/lichess-puzzler/blob/master/tagger/cook.py) does.

motif/src/main/scala/Motif.scala

@@ -0,0 +1,14 @@
+package chess
+package motif
+
+enum Motif:
+  case fork
+  case doubleCheck
+  case xRay
+
+case class MotifAt(motif: Motif, at: Ply)
+
+object MotifAt:
+
+  def findAll(replay: Replay): List[MotifAt] =
+    Nil