Pretty print programs partially

src/pretty/program.rs

@@ -0,0 +1,23 @@
+use pretty::RcDoc;
+
+use crate::ast::Program;
+
+impl Program {
+    pub fn to_doc(&self) -> RcDoc {
+        match self {
+            Program::Expr {
+                s0,
+                expr,
+                s1,
+                span: _,
+            } => RcDoc::nil(),
+            Program::Module {
+                s0,
+                s1,
+                elems,
+                s2,
+                span: _,
+            } => RcDoc::text("module"),
+        }
+    }
+}