Added missing method [plus] at type [unit].

Renaming.

src/BindingForms.ml

@@ -63,9 +63,9 @@ class virtual ['self] map = object (self : 'self)
     _ ->
     ('env -> 'term1 -> 'term2) ->
     'env -> ('bn1, 'term1) abs -> ('bn2, 'term2) abs
-  = fun _ f env (x, body) ->
+  = fun _ f env (x, t) ->
       let x', env' = self#extend x env in
-      x', f env' body
+      x', f env' t
 
   method private visit_def: 'term1 'term2 .
     _ ->
@@ -94,13 +94,13 @@ class virtual ['self] endo = object (self : 'self)
     _ ->
     ('env -> 'term -> 'term) ->
     'env -> ('bn, 'term) abs -> ('bn, 'term) abs
-  = fun _ f env ((x, body) as this) ->
+  = fun _ f env ((x, t) as this) ->
       let x', env' = self#extend x env in
-      let body' = f env' body in
-      if x == x' && body == body' then
+      let t' = f env' t in
+      if x == x' && t == t' then
         this
       else
-        x', body'
+        x', t'
 
   method private visit_def: 'term .
     _ ->
@@ -136,9 +136,9 @@ class virtual ['self] reduce = object (self : 'self)
     _ ->
     ('env -> 'term -> 'z) ->
     'env -> ('bn, 'term) abs -> 'z
-  = fun _ f env (x, body) ->
+  = fun _ f env (x, t) ->
       let env' = self#extend x env in
-      self#restrict x (f env' body)
+      self#restrict x (f env' t)
 
   method private visit_def: 'term .
     _ ->
@@ -160,6 +160,7 @@ class virtual ['self] iter = object (_ : 'self)
 
   inherit ['self] reduce
 
+  method private plus () () = ()
   method private restrict _ () = ()
 
 end
@@ -179,9 +180,9 @@ class virtual ['self] map2 = object (self : 'self)
     _ ->
     ('env -> 'term1 -> 'term2 -> 'term3) ->
     'env -> ('bn1, 'term1) abs -> ('bn2, 'term2) abs -> ('bn3, 'term3) abs
-  = fun _ f env (x1, body1) (x2, body2) ->
+  = fun _ f env (x1, t1) (x2, t2) ->
       let x3, env' = self#extend x1 x2 env in
-      x3, f env' body1 body2
+      x3, f env' t1 t2
 
   method private visit_def: 'term1 'term2 'term3 .
     _ ->
@@ -214,9 +215,9 @@ class virtual ['self] reduce2 = object (self : 'self)
     _ ->
     ('env -> 'term1 -> 'term2 -> 'z) ->
     'env -> ('bn1, 'term1) abs -> ('bn2, 'term2) abs -> 'z
-  = fun _ f env (x1, body1) (x2, body2) ->
+  = fun _ f env (x1, t1) (x2, t2) ->
       let env' = self#extend x1 x2 env in
-      self#restrict x1 x2 (f env' body1 body2)
+      self#restrict x1 x2 (f env' t1 t2)
 
   method private visit_def: 'term1 'term2 .
     _ ->
@@ -238,6 +239,7 @@ class virtual ['self] iter2 = object (_ : 'self)
 
   inherit ['self] reduce2
 
+  method private plus () () = ()
   method private restrict _ _ () = ()
 
 end