2 files changed, 6 insertions, 1 deletions
diff --git a/dhall_syntax/src/core/expr.rs b/dhall_syntax/src/core/expr.rs
index b293357..6522cb1 100644
--- a/dhall_syntax/src/core/expr.rs
+++ b/dhall_syntax/src/core/expr.rs
@@ -44,7 +44,7 @@ impl From<NaiveDouble> for f64 {
 }
 
 /// Constants for a pure type system
-#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
 pub enum Const {
     Type,
     Kind,
@@ -99,6 +99,8 @@ pub enum BinOp {
     BoolEQ,
     /// `x != y`
     BoolNE,
+    /// x === y
+    Equivalence,
 }
 
 /// Built-ins
@@ -175,6 +177,8 @@ pub enum ExprF<SubExpr, Embed> {
     Let(Label, Option<SubExpr>, SubExpr, SubExpr),
     ///  `x : t`
     Annot(SubExpr, SubExpr),
+    ///  `assert : t`
+    Assert(SubExpr),
     /// Built-in values
     Builtin(Builtin),
     // Binary operations
diff --git a/dhall_syntax/src/core/visitor.rs b/dhall_syntax/src/core/visitor.rs
index 68ad956..18f76d9 100644
--- a/dhall_syntax/src/core/visitor.rs
+++ b/dhall_syntax/src/core/visitor.rs
@@ -148,6 +148,7 @@ where
             ),
             Field(e, l) => Field(v.visit_subexpr(e)?, l.clone()),
             Projection(e, ls) => Projection(v.visit_subexpr(e)?, ls.clone()),
+            Assert(e) => Assert(v.visit_subexpr(e)?),
             Embed(a) => return v.visit_embed_squash(a),
         })
     }