fix judgment-form->rule-names and add its #:include-unnamed? argument

Author: rfindler

redex-doc/redex/scribblings/ref/other-relations.scrbl

@@ -627,10 +627,20 @@ helpful when debugging.
  See @racket[define-judgment-form] for more examples.
 }
 
-@defproc[(judgment-form->rule-names [r judgment-form?])
-         (listof symbol?)]{
+@defproc[(judgment-form->rule-names [r judgment-form?]
+                                    [#:include-unnamed? include-unnamed? any/c #f])
+         (listof (or/c symbol? #f))]{
 
-Returns the names of the judgment form's named clauses.
+ Returns the names of the judgment form's clauses.
+
+ If @racket[include-unnamed?] is @racket[#f] (the default)
+ then any case that does not have a name is not included in
+ the result and the result list contains only
+ @racket[symbol?]s.
+
+ Otherwise, each case is included in the result and unnamed
+ cases have a @racket[#false] at that position in the result
+ list.
 }
 
 

redex-lib/redex/private/reduction-semantics.rkt

@@ -2938,8 +2938,14 @@
   (cond
     [(reduction-relation? x) (reduction-relation->rule-names x)]
     [(IO-judgment-form? x) (runtime-judgment-form-rule-names x)]))
-(define (judgment-form->rule-names x)
-  (runtime-judgment-form-rule-names x))
+(define (judgment-form->rule-names x #:include-unnamed? [include-unnamed? #f])
+  (cond
+    [include-unnamed?
+     (runtime-judgment-form-rule-names x)]
+    [else
+     (for/list ([n (in-list (runtime-judgment-form-rule-names x))]
+                #:when n)
+       n)]))
 
 
 ;                                                                               

redex-lib/redex/reduction-semantics.rkt

@@ -97,7 +97,7 @@
 (provide/contract
  [current-traced-metafunctions (parameter/c (or/c 'all (listof symbol?)))]
  [reduction-relation->rule-names (-> reduction-relation? (listof symbol?))]
- [judgment-form->rule-names (-> judgment-form? (listof symbol?))]
+ [judgment-form->rule-names (->* (judgment-form?) (#:include-unnamed? any/c) (listof (or/c symbol? #f)))]
  [language-nts (-> compiled-lang? (listof symbol?))]
  [set-cache-size! (-> number? void?)]
  [apply-reduction-relation (-> (or/c IO-judgment-form? reduction-relation?)

redex-test/redex/tests/tl-judgment-form.rkt

@@ -2203,4 +2203,22 @@
      (J 1 2 3)])
   (test (judgment-holds (J 1 2 3)) #t))
 
+(let ()
+  (define-language L)
+  (define-judgment-form L
+    #:mode (J I)
+    [----- "1"
+     (J 1)]
+
+    [----- two
+     (J 1)]
+
+    [-----
+     (J 2)])
+  (test (judgment-form->rule-names J)
+        (list (string->symbol "1") 'two))
+
+  (test (judgment-form->rule-names J #:include-unnamed? #t)
+        (list (string->symbol "1") 'two #f)))
+
 (print-tests-passed 'tl-judgment-form.rkt)