1 files changed, 36 insertions, 0 deletions
diff --git a/dhall/src/semantics/nze/var.rs b/dhall/src/semantics/nze/var.rs
new file mode 100644
index 0000000..264b81d
--- /dev/null
+++ b/dhall/src/semantics/nze/var.rs
@@ -0,0 +1,36 @@
+use crate::syntax::Label;
+
+// Exactly like a Label, but equality returns always true.
+// This is so that ValueKind equality is exactly alpha-equivalence.
+#[derive(Clone, Eq)]
+pub struct Binder {
+    name: Label,
+}
+
+impl Binder {
+    pub(crate) fn new(name: Label) -> Self {
+        Binder { name }
+    }
+    pub(crate) fn to_label(&self) -> Label {
+        self.clone().into()
+    }
+}
+
+/// Equality up to alpha-equivalence
+impl std::cmp::PartialEq for Binder {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+
+impl std::fmt::Debug for Binder {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Binder({})", &self.name)
+    }
+}
+
+impl From<Binder> for Label {
+    fn from(x: Binder) -> Label {
+        x.name
+    }
+}