From a5140513dee8f3c8c995fcb540aff0d63bb3e994 Mon Sep 17 00:00:00 2001
From: Kasey White <kwhitemsg@gmail.com>
Date: Sat, 9 Jul 2022 22:12:51 -0400
Subject: [PATCH] fix: debruijn index - 1

Co-authored-by: rvcas <x@rvcas.dev>
---
 add_integers.uplc          | 2 +-
 crates/uplc/src/machine.rs | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/add_integers.uplc b/add_integers.uplc
index 5854dd64..b3c9bff8 100644
--- a/add_integers.uplc
+++ b/add_integers.uplc
@@ -1,4 +1,4 @@
 (program
   1.0.0
-  [ (builtin addInteger) (con integer 2) (con integer 3) ] 
+  [ (lam x (lam y [ (builtin addInteger) x y ])) (con integer 5) (con integer 7) ] 
 )
diff --git a/crates/uplc/src/machine.rs b/crates/uplc/src/machine.rs
index ce1bd594..e6f61836 100644
--- a/crates/uplc/src/machine.rs
+++ b/crates/uplc/src/machine.rs
@@ -168,7 +168,7 @@ impl Machine {
                         Term::Var(name)
                     } else {
                         this.env
-                            .get::<usize>(index - lam_cnt)
+                            .get::<usize>(index - lam_cnt - 1)
                             .cloned()
                             .map_or(Term::Var(name), |v| this.discharge_value(v))
                     }
@@ -262,7 +262,7 @@ impl Machine {
 
     fn lookup_var(&mut self, name: NamedDeBruijn) -> Result<Value, Error> {
         self.env
-            .get::<usize>(name.index.into())
+            .get::<usize>(usize::from(name.index) - 1)
             .cloned()
             .ok_or(Error::OpenTermEvaluated(Term::Var(name)))
     }