1 files changed, 25 insertions, 20 deletions

diff --git a/parsing/ast_mapper.mli b/parsing/ast_mapper.mli
index bf23a7af34..651717e5f1 100644
--- a/parsing/ast_mapper.mli
+++ b/parsing/ast_mapper.mli
@@ -62,15 +62,17 @@ val default_mapper: mapper
 
 
 val apply: source:string -> target:string -> mapper -> unit
-    (** Apply a mapper to a dumped parsetree found in the [source] file
-        and put the result in the [target] file. *)
-
-val main: mapper -> unit
-    (** Entry point to call to implement a standalone -ppx rewriter
-        from a mapper object. *)
+(** Apply a mapper (parametrized by the unit name) to a dumped
+    parsetree found in the [source] file and put the result in the
+    [target] file. The [structure] or [signature] field of the mapper
+    is applied to the implementation or interface.  *)
 
 val run_main: (string list -> mapper) -> unit
-    (** Same as [main], but with extra arguments from the command line. *)
+(** Entry point to call to implement a standalone -ppx rewriter from a
+    mapper, parametrized by the command line arguments.  The current
+    unit name can be obtained from [Location.input_name].  This
+    function implements proper error reporting for uncaught
+    exceptions. *)
 
 (** {2 Registration API} *)
 
@@ -78,19 +80,22 @@ val register_function: (string -> (string list -> mapper) -> unit) ref
 
 val register: string -> (string list -> mapper) -> unit
 
-    (** Apply the [register_function].  The default behavior is to run
-        the mapper immediately, taking arguments from the process
-        command line.  This is to support a scenario where a mapper is
-        linked as a stand-alone executable.
-
-        It is possible to overwrite the [register_function] to define
-        "-ppx drivers", which combine several mappers in a single
-        process.  Typically, a driver starts by defining
-        [register_function] to a custom implementation, then lets ppx
-        rewriters (linked statically or dynamically) register
-        themselves, and then run all or some of them.  It is also
-        possible to have -ppx drivers apply rewriters to only specific
-        parts of an AST.  *)
+(** Apply the [register_function].  The default behavior is to run the
+    mapper immediately, taking arguments from the process command
+    line.  This is to support a scenario where a mapper is linked as a
+    stand-alone executable.
+
+    It is possible to overwrite the [register_function] to define
+    "-ppx drivers", which combine several mappers in a single process.
+    Typically, a driver starts by defining [register_function] to a
+    custom implementation, then lets ppx rewriters (linked statically
+    or dynamically) register themselves, and then run all or some of
+    them.  It is also possible to have -ppx drivers apply rewriters to
+    only specific parts of an AST.
+
+    The first argument to [register] is a symbolic name to be used by
+    the ppx driver.  *)
+
 
 (** {2 Convenience functions to write mappers} *)