added a function for parsing contest files more easily

collects/2htdp/batch-io.rkt

@@ -35,6 +35,9 @@
  read-words/line ;; String -> [Listof [Listof String]]
  ;; read the specified file as a list of lines, each line as a list of words
  
+ read-words-and-numbers/line ;; String -> [Listof [Listof String]]
+ ;; read the specified file as a list of lines, each line as a list of words
+ 
  read-csv-file ;; String -> [Listof [Listof (U Any)]]
  ;; -- f must be formated as a a file with comma-separated values (Any)
  ;; read the specified file as a list of lists---one per line---of values (Any)
@@ -77,6 +80,12 @@
   ;; read the specified file as a list of lines, each line as a list of words
   (read-words/line/internal f cons))
 
+(def-reader (read-words-and-numbers/line f)
+  ;; String -> [Listof [Listof (U String Number)]]
+  ;; read the specified file as a list of lines, each line as a list of words and numbers
+  (read-words/line/internal f (lambda (line1 r)
+                                (cons (for/list ((t (in-list line1))) (or (string->number t) t)) r))))
+
 (define (read-words/line/internal f combine)
   (define lines (read-chunks f *read-line (lambda (x) x)))
   (foldl (lambda (f r)

collects/2htdp/tests/batch-io3.rkt

@@ -0,0 +1,107 @@
+#lang racket
+
+;; test for pr11445
+
+(require 2htdp/batch-io)
+
+(define batch-io3
+  #<<eos
+2      
+4 2    
+3 hamburger 3.00
+2 cheeseburger 1.50
+1 hamburger 1.00
+1 fries 0.75
+hamburger
+fries
+2 1    
+4 jackets 42.34
+2 jackets 21.17
+jackets
+eos
+  )
+
+(define batch-io3-expected
+  #<<eos
+You sold 4 hamburgers for a total of $4.00.
+You sold 1 fries for a total of $0.75.
+
+You sold 6 jackets for a total of $63.51.
+
+
+eos
+  )
+
+(define batch-io3.sexpr
+  '((2)
+    (4 2)
+    (3 "hamburger" 3.00)
+    (2 "cheeseburger" 1.50)
+    (1 "hamburger" 1.00)
+    (1 "fries" 0.75)
+    ("hamburger")
+    ("fries")
+    (2 1)
+    (4 "jackets" 42.34)
+    (2 "jackets" 21.17)
+    ("jackets")))
+
+(with-output-to-file "batch-io3.txt"
+  #:exists 'replace
+  (lambda ()
+    (printf batch-io3)))
+
+(define batch-io3.read 
+  (read-words-and-numbers/line "batch-io3.txt"))
+
+(with-handlers ((exn:fail:filesystem? void))
+  (delete-file "batch-io3.txt"))
+
+;; ---------------------------------------------------------------------------------------------------
+;; time to test results 
+
+(module+ test 
+  (require rackunit)
+  (check-equal? batch-io3.read batch-io3.sexpr))
+
+(module+ test
+  (define (split file n)
+    (values (drop file n) (take file n))))
+
+(module+ test
+  ;; String -> Void
+  ;; read input, process queries, write output 
+  (define (solution file-name)
+    ;; S-expression [Dataset -> String] -> String
+    (define (input->output i)
+      (let loop ((ds# (first (first i))) (file (rest i)))
+        (cond
+          [(zero? ds#) ""]
+          [else
+           (let*-values ([(file sales-records# queries#) (apply values (rest file) (first file))]
+                         [(file sales-records)           (split file sales-records#)]
+                         [(file queries)                 (split file queries#)])
+             (string-append (process-dataset sales-records queries) "\n" (loop (sub1 ds#) file)))])))
+    ;; Dataset -> String 
+    ;; process one dataset 
+    (define (process-dataset sales-records queries)
+      (foldr (λ (query r) (string-append (total-message sales-records (first query)) r)) "" queries))
+
+    ;; [Listof [List Number String Number]] String -> String 
+    ;; compute query result and turn into string 
+    (define (total-message sales-records query)
+      (define good* (filter (λ (sales-record) (string=? (second sales-record) query)) sales-records))
+      (define count (apply + (map first good*)))
+      (define value (apply + (map third good*)))
+      (format "You sold ~a ~a for a total of $~a.\n" 
+              count (add-s query (length good*)) (real->decimal-string value 2)))
+    ;; String Natural -> String 
+    ;; add s to string if plurality calls for it
+    (define (add-s str n)
+      (if (and (> n 1) (not (string=? (substring str (- (string-length str) 1)) "s")))
+          (string-append str "s")
+          str))
+    ;; -- in -- ;; should be write-file from batch io
+    (with-output-to-string (λ () (printf (input->output batch-io3.sexpr)))))
+  
+  (check-equal? (solution "don't care") batch-io3-expected))

collects/2htdp/xtest

@@ -15,6 +15,8 @@ run bad-draw.rkt
 run error-in-tick.rkt
 run error-in-draw.rkt
 run -t batch-io.rkt
+run -t batch-io2.rkt
+run -t batch-io3.rkt
 run clause-once.rkt
 run full-scene-visible.rkt
 run image-too-large.rkt

collects/teachpack/2htdp/scribblings/batch-io.scrbl

@@ -89,7 +89,7 @@ This time, however, the extra leading space of the second line of
 a part of the separator that surrounds the word @racket["good"].
 }
 
-@item{@reading[read-words/line (listof string?)]{a list of lists, one per line; each line is represented as a list of white-space separated tokens}
+@item{@reading[read-words/line (listof string?)]{a list of lists, one per line; each line is represented as a list of strings}
 
 @examples[#:eval (examples-batch-io)
 (read-words/line "data.txt")
@@ -99,6 +99,14 @@ except that the organization of the file into lines is preserved.
 In particular, the empty third line is represented as an empty list of words. 
 }
 
+@item{@reading[read-words-and-numbers/line (listof (or number? string?))]{a list of lists, one per line; each line is represented as a list of strings and numbers}
+
+@examples[#:eval (examples-batch-io)
+(read-words-and-numbers/line "data.txt")
+]
+The results is like the one that @racket[read-words/line] produces,
+except strings that can be parsed as numbers are represented as numbers.}
+
 @item{@reading[read-csv-file (listof (listof any/c))]{a list of lists of comma-separated values}
 
 @examples[#:eval (examples-batch-io)