Fixing an error in quoting found by a student this year

collects/plai/mutator.rkt

@@ -234,7 +234,7 @@
     [(_ (a . d))
      (mutator-app collector:cons (mutator-quote a) (mutator-quote d))]
     [(_ s) 
-     (mutator-app collector:alloc-flat 's)]))
+     (mutator-datum . s)]))
 (define-syntax (mutator-datum stx)
   (syntax-case stx ()
     [(_ . e) 

collects/tests/plai/gc/good-mutators/student20111116.rkt

@@ -0,0 +1,98 @@
+#lang plai/mutator
+(allocator-setup "../good-collectors/good-collector.rkt" 84)
+(halt-on-errors)
+
+;(check-temps1 temps) -> boolean?
+; temps : (listof number?)
+;Consumes a list of temperature measures and checks whether all measurements are between 5 and 95 degrees celsius (inclusively.)
+
+(define (check-temps1 temps)
+  (if (empty? temps) #t ;divide end of the list / empty list from not-the-end
+    (and ; ? this temp is between 5 & 95
+     (>= (first temps) 5)
+     (<= (first temps) 95)
+     (check-temps1 (rest temps)) ; ? and so are all the rest
+    )
+  )
+)
+
+(check-temps1 '(7 10 32 87))
+(check-temps1 '(7 4 32 87))
+(check-temps1 '(7 98 32 87))
+
+;(check-temps temps low high) -> boolean?
+;  temps : (listof number?)
+;  low : number?
+;  high : number?
+;Consumes a list of temperature measures and checks whether all measurements are between low and high degrees celsius (inclusively.)
+
+(define (check-temps temps low high)
+  (if (empty? temps) #t ;divide end of the list / empty list from not-the-end
+    (and ; ? this temp is between low & high
+     (>= (first temps) low)
+     (<= (first temps) high)
+     (check-temps (rest temps) low high) ; ? and so are all the rest
+    )
+  )
+)
+
+(check-temps '(7 10 32 87) 5 90)
+(check-temps '(7 10 32 87) 8 90)
+(check-temps '(7 10 32 87) 5 80)
+
+;(convert digits) -> number?
+;  digits : (listof number?)
+;Consumes a list of digits (numbers between 0 and 9) and produces the corresponding number. The first digit is the least significant, and so on.
+
+(define (convert digits)
+  (if (empty? digits) 0 ;at the end, don't add anything!
+    (+ (first digits) (* 10 (convert (rest digits))))
+  )
+)
+
+(convert '(1 2 3))
+
+;(average-price prices) -> number?
+;  prices : (listof number?)
+;Consumes a list of toy prices and computes the average price of a toy. The average is total of all prices divided by the number of toys.
+
+(define (count-prices prices sum count) ;need to introduce some extra parameters to hold the count & sum for averaging
+  (if (empty? prices) (/ sum count) ;end of the list- calculate the average
+    (count-prices (rest prices) (+ sum (first prices)) (+ count 1)) ;increment the count & update the total sum
+  )
+)
+(define (average-price prices)
+  (if (empty? prices) 0 ;divide special case empty list from everything else
+    (count-prices prices 0 0)
+  )
+)
+
+(average-price '())
+(average-price '(5 15 32 6))
+
+;(convertFC fahrenheit) -> (listof number?)
+;  fahrenheit : (listof number?)
+;Converts a list of of Fahrenheit measurements to a list of Celsius measurements.
+
+(define (convertFC fahrenheit)
+  (if (empty? fahrenheit) empty
+    (cons (* (- (first fahrenheit) 32) 5/9) (convertFC (rest fahrenheit)))
+  )
+)
+
+(convertFC '(-40 15 32 50 60 85))
+
+;(eliminate-exp ua lotp) -> (listof number?)
+;  ua : number?
+;  lotp : (listof number?)
+;Eliminates from lotp all toys whose price is greater than ua.
+
+(define (eliminate-exp ua lotp)
+  (cond
+    [(empty? lotp) empty] ; end of the list
+    [(> (first lotp) ua) (eliminate-exp ua (rest lotp))] ;skip this element
+    [else (cons (first lotp) (eliminate-exp ua (rest lotp)))] ;keep this element
+  )
+)
+
+(eliminate-exp 15 '(1 16 3 5 22 8))