1 files changed, 43 insertions, 0 deletions
diff --git a/aoc2018/day-04/day-04.rkt b/aoc2018/day-04/day-04.rkt
new file mode 100644
index 0000000..3660099
--- /dev/null
+++ b/aoc2018/day-04/day-04.rkt
@@ -0,0 +1,43 @@
+#lang racket
+
+(require advent-of-code
+         data/applicative
+         data/monad
+         megaparsack
+         megaparsack/text
+         threading)
+
+(struct entry (month day hour minute message) #:transparent)
+
+(define (parse-message chrs)
+  (define str (apply string chrs))
+  (match str
+    ["wakes up" 'awake]
+    ["falls asleep" 'asleep]
+    [shift (~> shift (string-trim "Guard #") (string-trim " begins shift") string->number)]))
+
+(define entry/p
+  (do (string/p "[1518-")
+      [month <- integer/p]
+      (char/p #\-)
+      [day <- integer/p]
+      space/p
+      [hour <- integer/p]
+      (char/p #\:)
+      [minute <- integer/p]
+      (string/p "] ")
+      [message <- (many/p any-char/p)]
+      (pure (entry month day hour minute (parse-message message)))))
+
+(define (parse-entry str)
+  (parse-result! (parse-string entry/p str)))
+
+(define entries
+  (~> (port->lines (open-aoc-input (find-session) 2018 4 #:cache #true)) (map parse-entry _)))
+
+(define sorted-entries
+  (~> entries
+      (sort < #:key entry-minute)
+      (sort < #:key entry-hour)
+      (sort < #:key entry-day)
+      (sort < #:key entry-month)))