diff --git a/src/eval/template.rs b/src/eval/capture.rs
similarity index 63%
rename from src/eval/template.rs
rename to src/eval/capture.rs
index 040685f89..b7052c70b 100644
--- a/src/eval/template.rs
+++ b/src/eval/capture.rs
@@ -1,29 +1,17 @@
 use super::*;
 use crate::syntax::visit::*;
 
-impl Eval for Spanned<&ExprTemplate> {
-    type Output = Value;
-
-    fn eval(self, ctx: &mut EvalContext) -> Self::Output {
-        let mut template = self.v.clone();
-        let mut visitor = CapturesVisitor::new(ctx);
-        visitor.visit_template(&mut template);
-        Value::Template(template)
-    }
-}
-
 /// A visitor that replaces all captured variables with their values.
-struct CapturesVisitor<'a> {
+#[derive(Debug)]
+pub struct CapturesVisitor<'a> {
     external: &'a Scopes<'a>,
     internal: Scopes<'a>,
 }
 
 impl<'a> CapturesVisitor<'a> {
-    fn new(ctx: &'a EvalContext) -> Self {
-        Self {
-            external: &ctx.scopes,
-            internal: Scopes::default(),
-        }
+    /// Create a new visitor for the given external scopes.
+    pub fn new(external: &'a Scopes) -> Self {
+        Self { external, internal: Scopes::default() }
     }
 }
 
@@ -43,7 +31,7 @@ impl<'a> Visitor<'a> for CapturesVisitor<'a> {
     fn visit_expr(&mut self, expr: &'a mut Expr) {
         if let Expr::Ident(ident) = expr {
             // Find out whether the identifier is not locally defined, but
-            // captured, and if so, replace it with it's value.
+            // captured, and if so, replace it with its value.
             if self.internal.get(ident).is_none() {
                 if let Some(value) = self.external.get(ident) {
                     *expr = Expr::CapturedValue(value.clone());
diff --git a/src/eval/mod.rs b/src/eval/mod.rs
index 9e45a67ba..af3303afc 100644
--- a/src/eval/mod.rs
+++ b/src/eval/mod.rs
@@ -3,13 +3,14 @@
 #[macro_use]
 mod value;
 mod call;
+mod capture;
 mod context;
 mod ops;
 mod scope;
 mod state;
-mod template;
 
 pub use call::*;
+pub use capture::*;
 pub use context::*;
 pub use scope::*;
 pub use state::*;
@@ -208,6 +209,17 @@ impl Eval for Spanned<&ExprDict> {
     }
 }
 
+impl Eval for Spanned<&ExprTemplate> {
+    type Output = Value;
+
+    fn eval(self, ctx: &mut EvalContext) -> Self::Output {
+        let mut template = self.v.clone();
+        let mut visitor = CapturesVisitor::new(&ctx.scopes);
+        visitor.visit_template(&mut template);
+        Value::Template(template)
+    }
+}
+
 impl Eval for Spanned<&ExprBlock> {
     type Output = Value;
 
diff --git a/src/syntax/mod.rs b/src/syntax/mod.rs
index 16e691a9f..d1fc6b779 100644
--- a/src/syntax/mod.rs
+++ b/src/syntax/mod.rs
@@ -12,6 +12,7 @@ pub use ident::*;
 pub use node::*;
 pub use span::*;
 pub use token::*;
+pub use visit::Visitor;
 
 use crate::pretty::{Pretty, Printer};