Add a UDP example

examples/udp_server.scm

@@ -0,0 +1,18 @@
+(load "../bindings/libc.scm")
+
+(define (check-err ret msg)
+  (cond
+    ((< ret 0)
+     (perror msg)
+     (raise msg))
+    (#t ret)))
+
+(define (udp-sock fx)
+  (fx 
+    (check-err 
+      (socket 'AF_INET 'SOCK_DGRAM 'IPPROTO_NONE)
+      "Unable to init UDP socket")))
+
+(udp-sock 
+  (lambda (s)
+    (printf "~a~%" s)))