···11+#lang typed/racket
22+33+;; looks terrible, i know, but i whanna show more syntax and simple hello, world is too ;; easy
44+55+;; Using higher-order occurrence typing
66+(define-type SrN (U String Number))
77+(: tog ((Listof SrN) -> String))
88+(define (tog l)
99+ (apply string-append
1010+ (filter string? l)))
1111+(tog (list 5 "hello "
1212+ 1/2 "from Racket" (sqrt -1)))