diff --git a/racket/typed/examples/roles/file-system.rkt b/racket/typed/examples/roles/file-system.rkt
new file mode 100644
index 0000000..7113c3c
--- /dev/null
+++ b/racket/typed/examples/roles/file-system.rkt
@@ -0,0 +1,34 @@
+#lang typed/syndicate/roles
+
+(define-constructor (file name content)
+  #:type-constructor FileT
+  #:with File (FileT String String))
+
+(define-type-alias FileDemand
+  (Observe (FileT String ★/t)))
+
+(define-constructor (save name content)
+  #:type-constructor SaveT
+  #:with Save (SaveT String String))
+
+(define-constructor (delete name)
+  #:type-constructor DeleteT
+  #:with Delete (DeleteT String))
+
+;; unique role
+(define-type-alias Server
+  (Role (server)
+        (Reacts (Know FileDemand)
+                (Role (_)
+                      (Shares File)))
+        (Reacts (Message Save))
+        (Reacts (Message Delete))))
+
+(define-type-alias Reader
+  (Role (reader)
+        (Shares FileDemand)))
+
+(define-type-alias Writer
+  (Role (writer)
+        (Sends Save)
+        (Sends Delete)))
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