diff --git a/forja/src/P.scala b/forja/src/P.scala
new file mode 100644
index 0000000..6b7af53
--- /dev/null
+++ b/forja/src/P.scala
@@ -0,0 +1,20 @@
+package forja
+
+into opaque type P[T] = P.Erased
+
+object P:
+  trait Meta[T]
+  object Meta:
+    def derived[T]: Meta[T] = ???
+  end Meta
+
+  given [T] => (meta: Meta[T]) => Conversion[T, P[T]]:
+    def apply(x: T): Erased = ???
+  end given
+
+  trait Erased
+
+  extension [T] (p: P[T])
+    def fixpoint(fn: PartialFunction[T, T]): P[T] = ???
+  end extension
+end P