updates

csp/csp.rkt

@@ -111,8 +111,12 @@ This class describes finite-domain Constraint Satisfaction Problems.
                       (define result null)
                       (for ([val (in-list (hash-ref domains var))])
                         (when (= (nconflicts var val assignment) 0)
-                          ;; what does this mean?
-                          ;; a = assignment.copy; a[var] = val
+                          (define a (hash-copy assignment)) ;; !! typo fix in original
+                          (hash-set! a var val)
+                          (set! result (append result (cons (cons var val) a)))))
+                      result)))
+              
+              ;; todo: calls to append need to mutate. 
               
               
               
@@ -530,4 +534,3 @@ def solve_zebra(algorithm=min_conflicts, **args):
                
     
 |#
-