maude: owise (otherwise) equations (8 tests, 229 total)

Parser reads trailing eq attributes (eq L = R [owise] .) via mau/split-attrs.
mau/crewrite-top is two-pass: ordinary equations first, owise last — an owise
catch-all fires only when no ordinary equation applies, regardless of
declaration order. Verified a catch-all declared first still defers.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

lib/maude/parser.sx

@@ -13,8 +13,8 @@
 ;;   subsort/subsorts A B < C < D .
 ;;   op/ops NAMES : ARITY -> RESULT [ATTRS] .
 ;;   var/vars NAMES : SORT .
-;;   eq LHS = RHS .            ceq LHS = RHS if COND .
-;;   rl [L] : LHS => RHS .     crl [L] : LHS => RHS if COND .
+;;   eq LHS = RHS [ATTRS] .       ceq LHS = RHS if COND [ATTRS] .
+;;   rl [L] : LHS => RHS .        crl [L] : LHS => RHS if COND .
 ;;
 ;; Terms: prefix application f(a,b) (op name may contain underscores, e.g.
 ;; the prefix form _+_(2,3)); mixfix prefix s_ written `s X`; mixfix infix
@@ -384,6 +384,8 @@
               (do (dict-set! acc :idem true) (loop (rest ts))))
             ((= (first ts) "ctor")
               (do (dict-set! acc :ctor true) (loop (rest ts))))
+            ((= (first ts) "owise")
+              (do (dict-set! acc :owise true) (loop (rest ts))))
             ((= (first ts) "id:")
               (do
                 (dict-set! acc :id (nth ts 1))
@@ -392,6 +394,10 @@
               (do
                 (dict-set! acc :prec (parse-number (nth ts 1)))
                 (loop (mau/drop ts 2))))
+            ((= (first ts) "label")
+              (do
+                (dict-set! acc :label (nth ts 1))
+                (loop (mau/drop ts 2))))
             (else (loop (rest ts))))))
       (do (loop toks) acc))))
 
@@ -404,6 +410,9 @@
       {}
       (mau/parse-attr-tokens (mau/strip-brackets toks)))))
 
+;; Split a token sequence into {:term tokens-before-bracket :attrs parsed}.
+(define mau/split-attrs (fn (toks) {:attrs (mau/parse-attrs (mau/drop-until toks "[")) :term (mau/take-until toks "[")}))
+
 ;; ---------- signature collection ----------
 
 (define
@@ -514,9 +523,9 @@
         conditional?
         (let
           ((rhs-toks (mau/take-until after "if"))
-            (cond-toks (rest (mau/drop-until after "if"))))
-          {:lhs (mau/parse-term lhs-toks grammar) :t :eq :cond (mau/parse-cond cond-toks grammar) :rhs (mau/parse-term rhs-toks grammar)})
-        {:lhs (mau/parse-term lhs-toks grammar) :t :eq :cond nil :rhs (mau/parse-term after grammar)}))))
+            (cond-raw (rest (mau/drop-until after "if"))))
+          (let ((csplit (mau/split-attrs cond-raw))) {:lhs (mau/parse-term lhs-toks grammar) :t :eq :cond (mau/parse-cond (get csplit :term) grammar) :rhs (mau/parse-term rhs-toks grammar) :owise (= (get (get csplit :attrs) :owise) true)}))
+        (let ((rsplit (mau/split-attrs after))) {:lhs (mau/parse-term lhs-toks grammar) :t :eq :cond nil :rhs (mau/parse-term (get rsplit :term) grammar) :owise (= (get (get rsplit :attrs) :owise) true)})))))
 
 (define
   mau/strip-label
@@ -548,8 +557,8 @@
             (let
               ((rhs-toks (mau/take-until after "if"))
                 (cond-toks (rest (mau/drop-until after "if"))))
-              {:lhs (mau/parse-term lhs-toks grammar) :label label :t :rule :cond (mau/parse-cond cond-toks grammar) :rhs (mau/parse-term rhs-toks grammar)})
-            {:lhs (mau/parse-term lhs-toks grammar) :label label :t :rule :cond nil :rhs (mau/parse-term after grammar)}))))))
+              {:lhs (mau/parse-term lhs-toks grammar) :label label :t :rule :cond (mau/parse-cond (get (mau/split-attrs cond-toks) :term) grammar) :rhs (mau/parse-term rhs-toks grammar)})
+            {:lhs (mau/parse-term lhs-toks grammar) :label label :t :rule :cond nil :rhs (mau/parse-term (get (mau/split-attrs after) :term) grammar)}))))))
 
 (define
   mau/collect-rules!