> anyone else has interesting solutions

Yes! go to mine tartaglia triangle repository, download the program, run it, choose the combinations experiment and feed 10 4 and you'll see coulored solutions in the triangle and the following output:

*** Combinations of 4 items in a group of 10

There are  210  (red tile position 10 - 4) different combinations (whe
+n the order does not matter) of 4 items in a group of 10.
There are  715  (green tile) different combinations with repetitions o
+f 4 items in group of 10.
[download]

More informations are provided upon request:

This is called combination (or k-combination) in mathematic, id est no
+ matter of the order of the elements and no repetition of elements.
The formula is the binomial coefiicent one.

               n!
 C(n,k) =  ----------
            k!(n-k)!
[download]

PS The following ugly oneliner to print all 5040 permutations

perl -E "say @$_ for grep{$$_[0]!=$$_[1] and $$_[0]!=$$_[2] and $$_[0]
+!=$$_[3] and $$_[1]!=$$_[2]
 and $$_[1]!=$$_[3] and $$_[2]!=$$_[3]} map { [split '',sprintf '%04s'
+,$_]} 0..9999;"
[download]

PPS cannabalizing the below elegant solution by johngg I got a better solution:

perl -e "print qq($_ ) for grep { ! m{(.).*\1} }map{sprintf '%04s',$_}0..9999"

L*