Walker: step directly into the effective method

core/generic/generic.factor

@@ -29,6 +29,8 @@ PREDICATE: method-spec < pair
 : order ( generic -- seq )
     "methods" word-prop keys sort-classes ;
 
+GENERIC: effective-method ( ... generic -- method )
+
 : next-method-class ( class generic -- class/f )
     order [ class< ] with subset reverse dup length 1 =
     [ drop f ] [ second ] if ;

core/generic/standard/standard.factor

@@ -118,6 +118,10 @@ M: standard-combination perform-combination
 
 M: standard-combination dispatch# #>> ;
 
+M: standard-generic effective-method
+    [ dispatch# (picker) call ] keep
+    [ order [ instance? ] with find-last nip ] keep method ;
+
 ERROR: inconsistent-next-method object class generic ;
 
 ERROR: no-next-method class generic ;

extra/tools/walker/walker.factor

@@ -3,7 +3,8 @@
 USING: threads kernel namespaces continuations combinators
 sequences math namespaces.private continuations.private
 concurrency.messaging quotations kernel.private words
-sequences.private assocs models arrays accessors ;
+sequences.private assocs models arrays accessors
+generic generic.standard ;
 IN: tools.walker
 
 SYMBOL: show-walker-hook ! ( status continuation thread -- )
@@ -68,15 +69,12 @@ M: object add-breakpoint ;
 : (step-into-dispatch) nth (step-into-quot) ;
 
 : (step-into-execute) ( word -- )
-    dup "step-into" word-prop [
-        call
-    ] [
-        dup primitive? [
-            execute break
-        ] [
-            word-def (step-into-quot)
-        ] if
-    ] ?if ;
+    {
+        { [ dup "step-into" word-prop ] [ "step-into" word-prop call ] }
+        { [ dup standard-generic? ] [ effective-method (step-into-execute) ] }
+        { [ dup primitive? ] [ execute break ] }
+        { [ t ] [ word-def (step-into-quot) ] }
+    } cond ;
 
 \ (step-into-execute) t "step-into?" set-word-prop