XSB Prolog: write my own setof function

Question

I need to get, from a keyboard input (list), a list without duplicates but without using the inbuild setof (or any other inbuild functions) in XSB prolog.

How do i write my own setof function?

Input and output should look like this:

|?-list([a,b,c,d,a,b,c,d,e,f],L).  

L=[a,b,c,d,e,f];

Thanks in advance.

i updated the post, we can't use any inbuild functions which puts sort out of the equasion — user3033489, Nov 26 '13 at 14:30
i know how to use member/2, but I think it's also inbuild, or am I wrong? this should be all written by myself.. — user3033489, Nov 26 '13 at 14:35
Write a `list/2` based upon the existence of a `member/2` predicate (call it `mem` or `has_element` or something not built in), then write the `mem/2` or `has_element/2` predicate, which is very simple. — lurker, Nov 26 '13 at 15:04

score 1 · Accepted Answer · answered Nov 26 '13 at 14:39

Using member/2 it's so easy: just make a copy of each element, with a recursive list/2, checking the head of input list it's not already in the target list. Checking could be performed by member/2, you will need to write your own... The entire program should be 4 lines of code.

XSB Prolog: write my own setof function

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