How to transpose a matrix in prolog

Question

How can I transpose a list like [[1,2,3][4,5,6][6,7,8]] to [[1,4,6],[2,7,8],[3,6,9]]?

To depict it: I\'d like to flip the matrix 90 degree

Answer 1

Another approach:

delete_one_list([], []).
delete_one_list([[_|L]|LLs], [L|Ls]) :-
  delete_one_list(LLs, Ls).

transpose_helper([], []).
transpose_helper([[X|_]|Xs], [X|Ys]) :-
  transpose_helper(Xs, Ys).

transpose([[]|_], []).
transpose(List, [L|Ls]) :-
  transpose_helper(List, L),
  delete_one_list(List, NewList),
  transpose(NewList, Ls).