2 files changed, 18 insertions, 2 deletions
diff --git a/tvix/eval/src/compiler/mod.rs b/tvix/eval/src/compiler/mod.rs
index 2ab7662386..2985c7e90e 100644
--- a/tvix/eval/src/compiler/mod.rs
+++ b/tvix/eval/src/compiler/mod.rs
@@ -54,7 +54,7 @@ struct LambdaCtx {
 impl LambdaCtx {
     fn new() -> Self {
         LambdaCtx {
-            lambda: Lambda::new_anonymous(),
+            lambda: Lambda::default(),
             scope: Default::default(),
             captures_with_stack: false,
         }
@@ -62,7 +62,7 @@ impl LambdaCtx {
 
     fn inherit(&self) -> Self {
         LambdaCtx {
-            lambda: Lambda::new_anonymous(),
+            lambda: Lambda::default(),
             scope: self.scope.inherit(),
             captures_with_stack: false,
         }
@@ -897,7 +897,13 @@ impl Compiler<'_> {
         N: ToSpan,
         F: FnOnce(&mut Compiler, LocalIdx),
     {
+        let name = self.scope()[outer_slot].name();
         self.new_context();
+
+        // Set the (optional) name of the current slot on the lambda that is
+        // being compiled.
+        self.context_mut().lambda.name = name;
+
         let span = self.span_for(node);
         let slot = self.scope_mut().declare_phantom(span, false);
         self.scope_mut().begin_scope();
diff --git a/tvix/eval/src/compiler/scope.rs b/tvix/eval/src/compiler/scope.rs
index 9269a3c44c..83fba6eed7 100644
--- a/tvix/eval/src/compiler/scope.rs
+++ b/tvix/eval/src/compiler/scope.rs
@@ -15,6 +15,8 @@ use std::{
     ops::Index,
 };
 
+use smol_str::SmolStr;
+
 use crate::opcode::{StackIdx, UpvalueIdx};
 
 #[derive(Debug)]
@@ -71,6 +73,14 @@ impl Local {
         }
     }
 
+    /// Retrieve the name of the given local (if available).
+    pub fn name(&self) -> Option<SmolStr> {
+        match &self.name {
+            LocalName::Phantom => None,
+            LocalName::Ident(name) => Some(SmolStr::new(name)),
+        }
+    }
+
     /// Is this local intentionally ignored? (i.e. name starts with `_`)
     pub fn is_ignored(&self) -> bool {
         match &self.name {