ja

README.md

@@ -1,3 +1,16 @@
 # racket-mimetypes
 
-Gives a mimetype for an extension
+Returns the MIME type for a file extension, file name, or path.
+
+The package uses a bundled fallback table and silently checks Apache's
+`mime.types` in a background thread. A successful update is checked again
+after seven days. A failed update is retried after one day. The validated
+table is cached below Racket's user cache directory.
+
+```racket
+(require racket-mimetypes)
+
+(mimetype-for-ext "music.opus")
+(mimetype-for-ext 'png)
+(mimetype-for-ext "unknown" #:default "application/octet-stream")
+```