How to get rid of duplicates in a list, but keep the order

Question

I am using Intermediate Student with Lambda in DrRacket, I was wondering how one would remove the duplicates in a list, while keeping the order. For example (remo

Answer 1

hmm i just had a racket exam recently, :/

the 'standard' remove-duplicates works fine but i was using pretty-big in drRacket so it had to be loaded using (require racket/list)

here is an alternative way :)

using mutation (not really in the spirit of racket but.. it works.)

    (define (set l)
        (define the-set '())
            (begin (for-each
                       (lambda (x)
                            (if (member x the-set)
                                #t
                            (set! the-set (cons x the-set))))
                       l)
                   (reverse the-set)))

hope this helps... cheers!