Fix some variable shifting failures

1 files changed, 8 insertions, 0 deletions

diff --git a/dhall/src/semantics/nze/nzexpr.rs b/dhall/src/semantics/nze/nzexpr.rs
index 723c895..49aa704 100644
--- a/dhall/src/semantics/nze/nzexpr.rs
+++ b/dhall/src/semantics/nze/nzexpr.rs
@@ -217,6 +217,9 @@ impl QuoteEnv {
     pub fn new() -> Self {
         QuoteEnv { size: 0 }
     }
+    pub fn construct(size: usize) -> Self {
+        QuoteEnv { size }
+    }
     pub fn insert(&self) -> Self {
         QuoteEnv {
             size: self.size + 1,
@@ -231,6 +234,11 @@ impl NzVar {
     pub fn new(idx: usize) -> Self {
         NzVar { idx }
     }
+    pub fn shift(&self, delta: isize) -> Self {
+        NzVar {
+            idx: (self.idx as isize + delta) as usize,
+        }
+    }
 }
 
 impl TyExpr {