diff --git a/src/pretty.rs b/src/pretty.rs
index 3847c62..4fe06c6 100644
--- a/src/pretty.rs
+++ b/src/pretty.rs
@@ -1 +1,2 @@
+mod basic;
 mod program;
diff --git a/src/pretty/basic.rs b/src/pretty/basic.rs
new file mode 100644
index 0000000..2ee19db
--- /dev/null
+++ b/src/pretty/basic.rs
@@ -0,0 +1,38 @@
+use pretty::RcDoc;
+
+use crate::ast::Separated;
+
+impl<E, S1, S2> Separated<E, S1, S2> {
+    pub fn to_doc<FE, FS1, FS2>(
+        &self,
+        elem_to_doc: FE,
+        separator_to_doc: FS1,
+        trailing_separator_to_doc: FS2,
+    ) -> RcDoc
+    where
+        FE: Fn(&E) -> RcDoc,
+        FS1: Fn(&S1) -> RcDoc,
+        FS2: Fn(&S2) -> RcDoc,
+    {
+        match self {
+            Separated::Empty(_) => RcDoc::nil(),
+            Separated::NonEmpty {
+                first_elem,
+                last_elems,
+                trailing,
+                span: _span,
+            } => elem_to_doc(first_elem)
+                .append(RcDoc::concat(
+                    last_elems
+                        .iter()
+                        .map(|(s, e)| separator_to_doc(s).append(elem_to_doc(e))),
+                ))
+                .append(
+                    trailing
+                        .as_ref()
+                        .map(trailing_separator_to_doc)
+                        .unwrap_or_else(RcDoc::nil),
+                ),
+        }
+    }
+}
diff --git a/src/pretty/program.rs b/src/pretty/program.rs
index 60a5ca0..6af1ac4 100644
--- a/src/pretty/program.rs
+++ b/src/pretty/program.rs
@@ -10,14 +10,21 @@ impl Program {
                 expr,
                 s1,
                 span: _,
-            } => RcDoc::nil(),
+            } => RcDoc::text("<expr>"),
             Program::Module {
                 s0,
                 s1,
                 elems,
                 s2,
                 span: _,
-            } => RcDoc::text("module"),
+            } => RcDoc::text("module")
+                .append(RcDoc::line())
+                .append(RcDoc::line())
+                .append(elems.to_doc(
+                    |e| RcDoc::text("<elem>"),
+                    |(s0, s1)| RcDoc::text(",").append(RcDoc::line()),
+                    |s| RcDoc::text(","),
+                )),
         }
     }
 }