diff --git a/src/flat.rs b/src/flat.rs
new file mode 100644
index 00000000..a8991206
--- /dev/null
+++ b/src/flat.rs
@@ -0,0 +1,29 @@
+pub trait Encode {
+    fn encode(&self, e: &mut Encoder) -> Result<(), String>;
+}
+
+pub struct Encoder {
+    pub bytes: Vec<u8>,
+}
+
+impl Default for Encoder {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl Encoder {
+    pub fn new() -> Encoder {
+        Encoder { bytes: Vec::new() }
+    }
+
+    /// Encode any type that implements [`Encode`].
+    pub fn encode<T: Encode>(&mut self, x: T) -> Result<&mut Self, String> {
+        x.encode(self)?;
+        Ok(self)
+    }
+
+    pub fn u8(&mut self, x: u8) -> Result<&mut Self, String> {
+        todo!()
+    }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 8f60fde7..d912086e 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,6 +1,7 @@
 pub mod ast;
 pub mod builtins;
 pub mod cli;
+pub mod flat;
 pub mod parser;
 
 #[macro_use]