bug eliminated from _words_ reading

collects/2htdp/batch-io.ss

@@ -61,13 +61,19 @@
   (read-chunks f read-line reverse))
 
 (def-reader (read-as-words f)
-  (define lines (read-chunks f read-line reverse))
-  (foldr (lambda (f r) (append (split f) r)) '() lines))
+  (read-as-words/line/internal f append))
 
 (def-reader (read-as-words/line f)
   ;; String -> [Listof [Listof String]]
   ;; read the specified file as a list of lines, each line as a list of words
-  (map split (read-chunks f read-line reverse)))
+  (read-as-words/line/internal f cons))
+
+(define (read-as-words/line/internal f combine)
+  (define lines (read-chunks f read-line (lambda (x) x)))
+  (foldl (lambda (f r)
+           (define fst (filter (compose not (curry string=? "")) (split f)))
+           (if (empty? fst) r (combine fst r)))
+         '() lines))
 
 (def-reader (read-as-csv f)
   (read-as-csv/func f))

collects/2htdp/tests/batch-io.ss

@@ -45,6 +45,19 @@ eos
 (write-file file test2)
 (check-equal? (read-as-1strings file) as-1strings2 "as-lines 2")
 
+(define test2-a-as-list '("test1" "" "test2"))
+
+(define test2-a
+  (apply string-append 
+         (list (first test2-as-list)
+               (string #\newline)
+               (string #\newline)
+               (second test2-as-list))))
+
+(write-file file test2-a)
+(check-equal? (read-as-lines file) test2-a-as-list "as-lines 2-a")
+(check-equal? (read-as-words file) '("test1" "test2") "as-words 2-a")
+
 (define test3 #<< eos
  word1, word2 
  word3, word4
@@ -59,7 +72,7 @@ eos
 (check-equal? (read-as-csv file) '(("word1" "word2") ("word3" "word4"))
               "as-cvs 1")
 (check-equal? (read-as-csv/rows file length) '(2 2) 
-  "as-words/rows")
+              "as-csv/rows")
 
 
 (check-exn exn:fail:contract? (lambda () (write-file 0 1)))