codelibs_iteration_3.rkt

codelibs_iteration_3.rkt

#lang at-exp racket

(require (for-syntax racket/match))
(require (for-syntax racket/syntax))

(define-namespace-anchor anc)
(define ns (namespace-anchor->namespace anc))

; with adjusted macros from text madlibs

(define (ask prompt)
  (display prompt)
  (read-line))  

(define prompt-responses
  (make-hash (list )))

; Given variable & prompt, checks if we've recorded a response and prompts as needed. Returns stored/new response.
(define (lookup-or-ask var prompt)
  (if (null? (hash-ref prompt-responses var null))
      (let ([response (ask prompt)])
                (hash-set! prompt-responses var response))
      null)
  (hash-ref prompt-responses var null))

(define (string->procedure str)
  (define operator-hash (hash "+" + "-" - "*" * "/" /))
  (hash-ref operator-hash str null))

; Given variable type, get the appropriate function to reformat response
(define (get-reformatter var-type)
  (define reformat-hash (hash "number" string->number "operator" string->procedure))
  (hash-ref reformat-hash var-type null))

(define-syntax-rule (blank var-type var prompt)
  (let ([reformat-function (get-reformatter var-type)])
    (reformat-function (lookup-or-ask var prompt))))

;; Code templates

(define-syntax (code-template stx)
  (match (syntax->datum stx)
    [(list _ template-name operation)
     (datum->syntax stx `(define (,(string->symbol template-name)) (eval ,operation ns)))]))

(code-template "add-story" (+ (blank "number" "n1" "A number: ") (blank "number" "n2" "Another number: ")))
(code-template "multiply-story" `(* (blank "number" "n1" "A number: ") (blank "number" "n2" "Another number: ")))
(code-template "change-operator" `((blank "operator" "op1" "Pick an operator (+, -, * or /)") 5 10))
(code-template "do-something-to-10" `((blank "operator" "op1" "Pick an operator (+, -, * or /)") 10 (blank "number" "n1" "A number: ")))