Question

我在CPN ML工作，这与SML大致相同。我确信以下部分代码可以正常工作：

color Product = string; 
color Number = int;
color StockItem = record prod:Product * number:Number; 
color Stock = list StockItem; 
var x:StockItem; var s:Stock;

fun incrs(x:StockItem,s:Stock) = 
  if s=[] then [x] 
  else (if (#prod(hd(s)))=(#prod(x))
  then {prod=(#prod(hd(s))),number=((#number(hd(s)))+(#number(x)))}::tl(s)   
  else hd(s):: incrs(x,tl(s)));


fun decrs(x:StockItem,s:Stock)= incrs({prod=(#prod(x)),
    number=(~(#number(x)))},s)

现在我的问题是我需要为每个商店（学生任务）保留商店。所以我做了以下改编：

color Store = string;
color StockItem = record prod:Product * number:Number * store:Store;

fun incrs(x:StockItem,s:Stock) = 
  if s=[] 
  then [x] 
  else (if {(#prod(hd(s)))=(#prod(x)), (#STORE(hd(s)))=(#STORE(x))}  
        then {prod=(#prod(hd(s))),
              STORE = (#STORE(hd(s))), 
              number=((#number(hd(s)))+(#number(x)))}::tl(s)   
        else hd(s):: incrs(x,tl(s)));

最后一行代码似乎不起作用。有人可以帮我吗？非常感谢!!

ML小编码错误

0 个答案: