#lang racket/base (provide item-callback) (define (item-callback str) (surround-char str #\; ";;") ) (define (surround-char str char [prefix ""] [suffix prefix]) (let ([line (string-append prefix (build-string (+ 4 (string-length str)) (λ(i) char)) suffix "\n")]) (string-append line prefix (string char) " " str " " (string char) suffix "\n" line))) ;;