Produce comments in the generated .mli file.

TODO

-* Include comments in the generated .mli file (Interface)?
-
 * Document the incremental interface
 
 * Confirm and understand why the code back-end slows down by 50%

src/IL.mli

@@ -50,6 +50,8 @@ and interface_item =
   | IIInclude of module_type
     (* Submodule. *)
   | IIModule of string * module_type
+    (* Comment. *)
+  | IIComment of string
 
 and module_type =
   | MTNamedModuleType of string

src/interface.ml

@@ -62,6 +62,7 @@ let entrytypescheme_incremental symbol =
 
 let table_interface =
   if Settings.table then [
+    IIComment "The incremental API.";
     IIModule (
       interpreter,
       MTWithType (
@@ -71,6 +72,7 @@ let table_interface =
         ttoken
       )
     );
+    IIComment "The entry points to the incremental API.";
     IIValDecls (
       StringSet.fold (fun symbol decls ->
         (incremental symbol, entrytypescheme_incremental symbol) :: decls
@@ -82,8 +84,11 @@ let table_interface =
 
 let interface = [
   IIFunctor (PreFront.grammar.parameters, [
+    IIComment "This exception is raised by the monolithic API functions.";
     IIExcDecls [ excdef ];
+    IIComment "The type of tokens.";
     IITypeDecls tokentypedef;
+    IIComment "The monolithic API.";
     IIValDecls (
       StringSet.fold (fun symbol decls ->
         (Misc.normalize symbol, entrytypescheme symbol) :: decls

src/printer.ml

@@ -685,6 +685,8 @@ and interface_item f = function
       fprintf f "include %a%t%t" module_type mt nl nl
   | IIModule (name, mt) ->
       fprintf f "module %s : %a%t%t" name module_type mt nl nl
+  | IIComment comment ->
+      fprintf f "(* %s *)%t" comment nl
 
 and interface f i =
   list interface_item nothing f i