From 2011f132f786b660ba100de6a6f5a940bf08cd89 Mon Sep 17 00:00:00 2001
From: Camden Dixie O'Brien <cdo@wip.sh>
Date: Sat, 26 Sep 2026 10:40:44 +0100
Subject: [PATCH] Write demo program

---
 src/bin/demo.rs | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 src/bin/demo.rs

diff --git a/src/bin/demo.rs b/src/bin/demo.rs
new file mode 100644
index 0000000..846557e
--- /dev/null
+++ b/src/bin/demo.rs
@@ -0,0 +1,20 @@
+use deriv::expression::Expression;
+use deriv::eval::Evaluator;
+use deriv::repl::Repl;
+
+struct DummyEvaluator;
+
+impl Evaluator for DummyEvaluator {
+	type Expr = Expression;
+	type Error = std::io::Error;
+
+	fn eval(&mut self, input: Self::Expr) -> Result<Self::Expr, Self::Error> {
+		Ok(input)
+	}
+}
+
+fn main() -> std::io::Result<()> {
+	let mut repl = Repl::new(
+		std::io::stdin(), std::io::stdout(), DummyEvaluator {});
+	repl.run()
+}