Typos.

src/BindingFormsUnbound.ml

@@ -216,7 +216,7 @@ class virtual ['self] map = object (self : 'self)
       | DoNotVisit ->
           Obj.magic ()
 
-  (* [visit_abstraction] updates the enriched environment using the auxiliary
+  (* [visit_rebind] updates the enriched environment using the auxiliary
      function [rebind]. *)
 
   method private visit_rebind: 'env 'p1 'p2 .
@@ -225,7 +225,7 @@ class virtual ['self] map = object (self : 'self)
   = fun visit_p penv p1 ->
       visit_p (rebind penv) p1
 
-  (* A [recursive] is construct is visited in two successive phases. In the
+  (* A [recursive] construct is visited in two successive phases. In the
      first phase, we use [Extend/DoNotVisit] mode, which means that the
      [current] component of the enriched environment is extended, but nothing
      else happens. The result of this phase is discarded. (It MUST be