Ensuring variables match nothing else before, so is it CLP? Not possible in Tau Prolog?

Help!
1

I’m using: Tau Prolog

Is there another way than to create a giant list of \= between a large list of values when there can only be one of each in the result? Doing it with recursion on the list would effectively be doing the same, as I understand, with the likelihood that it’ll be slower.

    C1=a,
	C2=b,
	C3=c,
	C4=d,
	C5=e,	
	
	alldif([S1,S2,S3,S4,S5,S6,S7,S8]),
	prefers(S1,C1,P1),
	prefers(S2,C1,P2),
	prefers(S3,C1,P3),
	prefers(S4,C2,P4),
	prefers(S5,C2,P5),
	prefers(S6,C3,P6),
	prefers(S7,C4,P4),
    prefers(S8,C5,P4),

Doing something like the above, setting S1\=S2 between everything and everything else, before calling the prefers/3 predicates would be better, but I’m also struggling with this in tau since maplist/2 can’t use dif/1, as I understand it doesn’t exist.

Really, I’d like something that automatically states that cantbeausedasanyother/1.