Visual guarding and predicate cleanup

engine/guards.scm

@@ -1,7 +1,8 @@
 (module (engine guards) ()
 (import scheme
 	(chicken base)
-	(chicken module))
+	(chicken module)
+	(srfi 99))
 
 ;; Utility function for guarding parameter values
 (export guarded-parameter)
@@ -10,4 +11,15 @@
 			    (if (predicate val)
 				val
 				default))))
+
+;; Shorthand for defining a guarded mutator for a record field
+(define (guarded-mutator record-type field predicate)
+  (lambda (rec val)
+    (assert (record-type rec))
+    (assert (predicate val))
+    ((rtd-mutator (record-rtd rec) field) rec val)))
+
+;; TODO: define a similar function here for record constructor
+
+;; TODO: define a similar function here for binary operations on records
 )