ML small coding error

Question

I'm working in CPN ML, which is more or less the same as SML. I know for sure that the following part of code works:

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)

Now my problem is that I need to keep the store for each shop (a student task). So I made following adaptions:

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)));

The last line of code doesn't seem to work though. Can anyone help me please? Thanks a lot !!

In what way does the code not work? What is it supposed to do? — ben rudgers, Oct 27 '14 at 22:02
Are you meaning to test both conditions? Use `andalso`. Two booleans in a record does not make a boolean. — molbdnilo, Nov 06 '14 at 15:43

ML small coding error

0 Answers0