diff --git a/src/main/scala/leon/evaluators/RecursiveEvaluator.scala b/src/main/scala/leon/evaluators/RecursiveEvaluator.scala
index e6e516c67021ac3311377c00fc5e085b234dbcad..39d4cdbee50f2f83a369881529f3a24aa570b20f 100644
--- a/src/main/scala/leon/evaluators/RecursiveEvaluator.scala
+++ b/src/main/scala/leon/evaluators/RecursiveEvaluator.scala
@@ -13,7 +13,7 @@ import purescala.Extractors._
 
 import solvers.TimeoutSolver
 
-import xlang.Trees._
+import xlang.Expressions._
 import solvers.SolverFactory
 import synthesis.ConvertHoles.convertHoles
 
diff --git a/src/main/scala/leon/frontends/scalac/CodeExtraction.scala b/src/main/scala/leon/frontends/scalac/CodeExtraction.scala
index 379413feae6ab50069f05c8afb1d32517cb40d01..06d89326cebdac5064c2da3c36ccfe8b16f6e5f6 100644
--- a/src/main/scala/leon/frontends/scalac/CodeExtraction.scala
+++ b/src/main/scala/leon/frontends/scalac/CodeExtraction.scala
@@ -25,8 +25,8 @@ import purescala.Constructors._
 import purescala.ExprOps._
 import purescala.TypeOps._
 import purescala.DefOps.packageOf
-import xlang.Trees.{Block => LeonBlock, _}
-import xlang.TreeOps._
+import xlang.Expressions.{Block => LeonBlock, _}
+import xlang.ExprOps._
 
 import utils.{DefinedPosition, Position => LeonPosition, OffsetPosition => LeonOffsetPosition, RangePosition => LeonRangePosition}
 
diff --git a/src/main/scala/leon/solvers/z3/AbstractZ3Solver.scala b/src/main/scala/leon/solvers/z3/AbstractZ3Solver.scala
index bc2571639c3d49d8475a8a89903f0f796f47cc80..331bc00089e3bb3d6ab1758b9d497a1d98664cb2 100644
--- a/src/main/scala/leon/solvers/z3/AbstractZ3Solver.scala
+++ b/src/main/scala/leon/solvers/z3/AbstractZ3Solver.scala
@@ -13,7 +13,7 @@ import purescala.Constructors._
 import purescala.Extractors._
 import purescala.Expressions._
 import purescala.TypeOps._
-import xlang.Trees._
+import xlang.Expressions._
 import purescala.ExprOps._
 import purescala.Types._
 
diff --git a/src/main/scala/leon/verification/InjectAsserts.scala b/src/main/scala/leon/verification/InjectAsserts.scala
index cdeae613b36106909d3a0d160731c3365c243abb..0a67d9cc0d28f7e176dd0307a70016d959ce6245 100644
--- a/src/main/scala/leon/verification/InjectAsserts.scala
+++ b/src/main/scala/leon/verification/InjectAsserts.scala
@@ -4,7 +4,7 @@ package leon
 package utils
 
 import purescala.Expressions._
-import xlang.Trees._
+import xlang.Expressions._
 import purescala.ExprOps._
 import purescala.Definitions._
 import purescala.Constructors._
diff --git a/src/main/scala/leon/xlang/ArrayTransformation.scala b/src/main/scala/leon/xlang/ArrayTransformation.scala
index 63a454ecc0b065f3a57c9c73d5d967b5e3a3d9bf..90360fe3d35c2f42514c4bf36f76b18b53c507ef 100644
--- a/src/main/scala/leon/xlang/ArrayTransformation.scala
+++ b/src/main/scala/leon/xlang/ArrayTransformation.scala
@@ -7,7 +7,7 @@ import leon.LeonContext
 import leon.purescala.Common._
 import leon.purescala.Definitions._
 import leon.purescala.Expressions._
-import leon.xlang.Trees._
+import leon.xlang.Expressions._
 import leon.purescala.Extractors._
 import leon.purescala.Types._
 
diff --git a/src/main/scala/leon/xlang/EpsilonElimination.scala b/src/main/scala/leon/xlang/EpsilonElimination.scala
index 3a1c8498e8a33b54655ce199f726e72d672cb34a..6891bdd4b21c025fbdfb3ac712bafad21f2437de 100644
--- a/src/main/scala/leon/xlang/EpsilonElimination.scala
+++ b/src/main/scala/leon/xlang/EpsilonElimination.scala
@@ -8,7 +8,7 @@ import leon.purescala.Common._
 import leon.purescala.Definitions._
 import leon.purescala.Expressions._
 import leon.purescala.ExprOps._
-import leon.xlang.Trees._
+import leon.xlang.Expressions._
 
 object EpsilonElimination extends TransformationPhase {
 
diff --git a/src/main/scala/leon/xlang/TreeOps.scala b/src/main/scala/leon/xlang/ExprOps.scala
similarity index 95%
rename from src/main/scala/leon/xlang/TreeOps.scala
rename to src/main/scala/leon/xlang/ExprOps.scala
index 296bfe9f79ab7dc20646c63ad14bc170c7a962bc..c62240c724c37424ab796b942ea79a6868674861 100644
--- a/src/main/scala/leon/xlang/TreeOps.scala
+++ b/src/main/scala/leon/xlang/ExprOps.scala
@@ -4,10 +4,10 @@ package leon
 package xlang
 
 import purescala.Expressions._
-import xlang.Trees._
+import xlang.Expressions._
 import purescala.ExprOps._
 
-object TreeOps {
+object ExprOps {
   
   def isXLang(expr: Expr): Boolean = exists {
     case Block(_, _) | Assignment(_, _) |
diff --git a/src/main/scala/leon/xlang/Trees.scala b/src/main/scala/leon/xlang/Expressions.scala
similarity index 99%
rename from src/main/scala/leon/xlang/Trees.scala
rename to src/main/scala/leon/xlang/Expressions.scala
index 095340622137be9d19d98468530fe58cf88fd0ab..1e4cb75abcdb33bf3c0df168eb191cd865860d1c 100644
--- a/src/main/scala/leon/xlang/Trees.scala
+++ b/src/main/scala/leon/xlang/Expressions.scala
@@ -10,7 +10,7 @@ import purescala.Extractors._
 import purescala.{PrettyPrintable, PrinterContext}
 import utils._
 
-object Trees {
+object Expressions {
   import purescala.PrinterHelpers._
 
   case class Block(exprs: Seq[Expr], last: Expr) extends Expr with NAryExtractable with PrettyPrintable {
diff --git a/src/main/scala/leon/xlang/ImperativeCodeElimination.scala b/src/main/scala/leon/xlang/ImperativeCodeElimination.scala
index 5622b4e44bc3d297731f2d3c9490e0bc6fa91ae6..e3fc725b61021895fc7b3e9605d41a3a55e33e03 100644
--- a/src/main/scala/leon/xlang/ImperativeCodeElimination.scala
+++ b/src/main/scala/leon/xlang/ImperativeCodeElimination.scala
@@ -10,7 +10,7 @@ import leon.purescala.Extractors._
 import leon.purescala.Constructors._
 import leon.purescala.ExprOps._
 import leon.purescala.TypeOps._
-import leon.xlang.Trees._
+import leon.xlang.Expressions._
 
 object ImperativeCodeElimination extends LeonPhase[Program, (Program, Set[FunDef])] {
 
diff --git a/src/main/scala/leon/xlang/NoXLangFeaturesChecking.scala b/src/main/scala/leon/xlang/NoXLangFeaturesChecking.scala
index 38a42c494dccfddfd391bb6e220383c319069289..80f0e1a72795a4e55fe0c00422e6aea81d9b32a2 100644
--- a/src/main/scala/leon/xlang/NoXLangFeaturesChecking.scala
+++ b/src/main/scala/leon/xlang/NoXLangFeaturesChecking.scala
@@ -8,7 +8,7 @@ import purescala.Definitions._
 
 import utils.Position
 
-import xlang.Trees._
+import xlang.Expressions._
 
 object NoXLangFeaturesChecking extends UnitPhase[Program] {