langify

2016/day05-input.rkt

@@ -0,0 +1,2 @@
+#lang aoc-racket/2016/day05
+ojvtpuvg

2016/day05.rkt

@@ -1,15 +1,25 @@
-#lang br
+#lang br/quicklang
 (require openssl/md5)
 
-(define key "ojvtpuvg")
+(define (read-syntax path port)
+  (strip-bindings
+   #`(module mod "day05.rkt"
+       (solve-part-a #,(string-trim (port->string port))))))
+(module+ reader (provide read-syntax))
 
-(let loop ([idx 0][password-cs empty])
-  (cond
-    [(= 8 (length password-cs))
-     (apply string-append (reverse password-cs))]
-    [else
-     (define this-key (format "~a~a" key idx))
-     (define next-hash (md5 (open-input-string this-key)))
-     (if (string-prefix? next-hash "00000")
-         (loop (add1 idx) (cons (substring next-hash 5 6) password-cs))
-         (loop (add1 idx) password-cs))]))
+(provide #%module-begin)
+
+(define (solve-part-a key)
+  (display "part a solution: ")
+  (for*/fold ([password-cs empty])
+            ([idx (in-naturals)]
+             [this-key (in-value (format "~a~a" key idx))]
+             #:break (= 8 (length password-cs)))
+    (define this-hash (md5 (open-input-string this-key)))
+    (if (string-prefix? this-hash "00000")
+        (let ([next-str (substring this-hash 5 6)])
+          (display next-str)
+          (cons next-str password-cs))
+        password-cs))
+  (displayln ""))
+(provide solve-part-a)