GNU Artanis provides Python3-like template strings:
(make-string-template tpl . vals)
For example:
(define st (make-string-template "hello ${name}"))
(st #:name "nala")
;; ==> "hello nala"
;; or you may specify a default value for ${name}
(define st (make-string-template "hello ${name}" #:name "unknown"))
(st)
;; ==> "hello unknown"
(st #:name "john")
;; ==> "hello john"