[Nady990]

i wrote this code :

datatype 'a Multilist = t1 of 'a list 
                       |t2 of 'a Multilist list ;
fun h num [] = []
	|h num (x::xs) = (x,num)::h num xs ; 

fun f(n,(t1 l)) = h(n,l) 
   |f(n,(t2 l)) = f(n+1,hd l) @ f(n,tl l); 

and i get this error :
operator and operand don't agree in the expression f(n,(t1 l)) and in f(n+1,hd l) @ f(n,tl l)
but i dont understand why i get this errors ?

[sepp2k]

First of all; You define h to take two arguments: an element and a list. However you try to call it with a single argument: the tuple (n,l). You should call it as h n l instead (or define it to take a tuple like you did with f).

Secondly the argument to f should be a tuple whose second element is of type MultiList. When you call it as f(n+1,hd l) that's fine because hd l is a MultiList. However f(n, tl l] is wrong because tl l is a list of MultiLists, not a single MultiList.

[Nady990]

now i wrote it this way :

fun f(n,(type1 l)) = h n l 
   |f(n,(type2 ls)) = f(n+1,hd ls) @ g(n,tl ls) 

 and g n [] = [] 
    |g n (type2 l)::ls) = f(n,l) @ g(n+1,ls) ; 

and i got this error : deleting RPAREN EQUALLOP , what does it mean ?

[sepp2k]

If the compiler says "deleting SOMETOKEN" that means it encountered a SOMETOKEN where it did not expect one. In this case it's complaining about a closing parentheses (RPAREN == Right PARENthesis == closing parenthesis). If you look at line 5, you'll see that there's two closing parentheses, but only one opening parenthesis, so it's no wonder the compiler is confused.