Tentative implementation of hoister

compiler/src/l3/CPSHoister.scala

@@ -3,6 +3,33 @@ package l3
 import SymbolicCPSTreeModuleLow._
 
 object CPSHoister extends (Tree => LetF) {
-  def apply(tree: Tree): LetF =
-    ???
+  def apply(tree: Tree): LetF = tree match {
+    case LetP(name, prim, args, body) =>
+      val LetF(funs, hoistedBody) = apply(body)
+      LetF(funs, LetP(name, prim, args, hoistedBody))
+
+    case LetC(cnts, body) =>
+      val (newCnts, funsHoistedCnts) = cnts
+        .map(cnt => (cnt, apply(cnt.body)))
+        .map { case (cnt, LetF(funs, body)) => (Cnt(cnt.name, cnt.args, body), funs)}
+        .unzip
+      val LetF(funsHoistedBody, hoistedBody) = apply(body)
+
+      val funsHoistedFlat = (funsHoistedCnts :+ funsHoistedBody).flatten
+
+      LetF(funsHoistedFlat, LetC(newCnts, hoistedBody))
+
+    case LetF(funs, body) =>
+      val (newFuns, funsHoistedFuns) = funs
+        .map(fun => (fun, apply(fun.body)))
+        .map { case (fun, LetF(funsHoisted, body)) =>
+          (Fun(fun.name, fun.retC, fun.args, body), funsHoisted)
+        }.unzip
+
+      val LetF(funsHoistedBody, hoistedBody) = apply(body)
+      val funsHoistedFlat = (funsHoistedFuns :+ funsHoistedBody).flatten
+      LetF(funsHoistedFlat, hoistedBody)
+
+    case e => LetF(Seq(), e)
+  }
 }