useless stuff: add watch script

.gitignore

@@ -2,3 +2,5 @@
 /inputs/*
 !/inputs/.gitkeep
 /.status.rktd
+*.zo
+*.dep

scripts/countdown

@@ -12,6 +12,7 @@ function init_day {
         scripts/get-challenge $day &
         sleep 1
         scripts/make-day $day
+        tmux split-pane -v -- "bash -li <<< 'watch $day; exec</dev/tty'"
         fg
         return 1
     fi

scripts/template.rktrkt

@@ -24,6 +24,6 @@
 
 (module+ main
   (define input (parse "inputs/@day"))
-  (answer @day 1 (part1 input))
-  (answer @day 2 (part2 input))
+  (answer @day 1 (time (part1 input)))
+  (answer @day 2 (time (part2 input)))
   (displayln "meow"))

scripts/watch

@@ -0,0 +1,42 @@
+#!/usr/bin/env racket
+#lang racket
+
+(require racket/rerequire racket/runtime-path)
+
+(define (reinvoke file)
+  (displayln "invoking module")
+  (define p (build-path file))
+  (dynamic-rerequire p)
+  (dynamic-require (list 'submod p 'main) #f)
+  (displayln "invocation complete"))
+
+(define (watch-forever file)
+  (sleep 0.2)
+  (define chg-evt (filesystem-change-evt file (lambda ()
+                                                (displayln "error watching file...")
+                                                (sleep 1) (watch-forever file))))
+  (define runner (thread (lambda () (reinvoke file))))
+
+  (define (handle-break _)
+    (cond
+      [(sync/timeout 0 runner)
+       (displayln "exiting")
+       (exit)]
+      [else
+       (displayln "killing module")
+       (kill-thread runner)
+       (filesystem-change-evt-cancel chg-evt)]))
+
+  (with-handlers ([exn:break? handle-break])
+    (sync chg-evt)
+    (kill-thread runner))
+  (watch-forever file))
+
+(define-runtime-path aoc "aoc.rkt")
+(command-line
+  #:program "watch"
+  #:args (day)
+  (displayln "warming up")
+  (dynamic-require aoc #f)
+  (displayln "ready to go!")
+  (watch-forever (format "~a.rkt" day)))