Fix: "Cache-busting" for static files

src/static-data.rkt

@@ -0,0 +1,18 @@
+#lang typed/racket/base
+(require racket/path
+         racket/runtime-path)
+
+(provide
+ get-static-url)
+
+(define-runtime-path path-static "../static")
+
+(define static-data
+  (for/hash ([f (directory-list path-static)]) : (Immutable-HashTable Path Nonnegative-Integer)
+    (define built (simple-form-path (build-path path-static f)))
+    (values built (file-or-directory-modify-seconds built))))
+
+(: get-static-url ((U String Path) -> String))
+(define (get-static-url path-or-filename)
+  (define the-path (simple-form-path (if (path? path-or-filename) path-or-filename (build-path path-static path-or-filename))))
+  (format "/static/~a?t=~a" (file-name-from-path the-path) (hash-ref static-data the-path)))