I think simple "map" does what you want: map(append,[[1,2],[3,4]],[[a,b],[c,d]]); => [[1,2,a,b],[3,4,c,d]] On 9/12/06, Nicolas Neuss <neuss at mathematik.uni-karlsruhe.de> wrote: > outermap(append,[[1,2],[3,4]],[[a,b],[c,d]]); > I want to obtain [[1,2,a,b], ...