Functional printf

printf.rkt

#lang racket

(define (to-function format acc)
  (match format
    [(list #\% #\d rest ...) (lambda (i) (to-function rest (string-append acc (number->string i))))]
    [(list #\% #\s rest ...) (lambda (s) (to-function rest (string-append acc s)))]
    [(cons c rest) (to-function rest (string-append acc (string c)))]
    [null acc]))    

(define (printf format)
  (to-function (string->list format) ""))

(((printf "%d hello %s") 1) "some string")