Document purpose of ExtededTerm
@@ -18,6 +18,13 @@ pub mod utils;
mod tests;
/// Either a term or a toplevel let declaration.
+/// Used exclusively in the REPL to allow the defining of variables without having to specify `in`.
+/// For instance:
+/// ```text
+/// nickel>let foo = 1
+/// nickel>foo
+/// 1
+/// ```
pub enum ExtendedTerm {
RichTerm(RichTerm),
ToplevelLet(Ident, RichTerm),
