simplify

csp/csp/hacs-test-queens.rkt

@@ -12,27 +12,25 @@
 (define board-size 8)
 
 (define queens (make-csp))
-(define qs (for/list ([q board-size]) (string->symbol (format "q~a" q))))
+(define qs (range board-size))
 (define rows (range (length qs)))
 (add-vars! queens qs rows)
-(define (q-col q) (string->number (string-trim (symbol->string q) "q")))
 (for* ([qs (in-combinations qs 2)])
   (match-define (list qa qb) qs)
-  (match-define (list qa-col qb-col) (map q-col qs))
   (add-constraint! queens
                    (λ (qa-row qb-row)
-                     (not (= (abs (- qa-row qb-row)) (abs (- (q-col qa) (q-col qb)))))) ; same diag?
-                   (list qa qb))
-  (add-constraint! queens (negate =) (list qa qb)))
+                     (not (= (abs (- qa-row qb-row)) (abs (- qa qb))))) ; same diag?
+                   (list qa qb)))
+(add-all-diff-constraint! queens #:proc eq?)
 
 (define (sol->string sol)
   (define assocs (csp->assocs sol))
-   (string-join (for/list ([q (in-list (sort assocs string<? #:key (compose1 symbol->string car)))])
-    (apply string (add-between (for/list ([idx (in-range board-size)])
-      (if (= idx (cdr q)) #\@ #\·)) #\space))) "\n"))
+  (string-join (for/list ([q (in-list (sort assocs < #:key car))])
+                 (apply string (add-between (for/list ([idx (in-range board-size)])
+                                              (if (= idx (cdr q)) #\@ #\·)) #\space))) "\n"))
 
 (current-thread-count 4)
 (displayln (solve queens #:finish-proc sol->string))
-(parameterize ([current-solver min-conflicts-solver])
-    (time (solve queens)))
+(parameterize (#;[current-solver min-conflicts-solver])
+  (time (solve queens)))