How would you SPLIT a List in pieces of specified length ? …. Here is how :
:- initialization(main).
say(L) :- write(L), write('\n').
%%this illustrates how to pick part of a List
firstN(Lst,N,FirstN) :- length(FirstN,N), append(FirstN,_Rest,Lst).
split([],_,[]) :- !.
split(Lst, N, [FirstN|Res]) :-
length(FirstN, N), append(FirstN, Rest, Lst), !, split(Rest, N, Res).
%%when the last piece is smaller than the requested size
split(Lst, N, [Lst]) :- length(Lst, Len), Len < N.
main :-
L = [1,2,3,4,5,6], say(L),
firstN(L,5,F), say(F),
split(L,2,L2), say(L2),
split(L,3,L3), say(L3),
split(L,4,L4), say(L4).
----
[1,2,3,4,5,6]
[1,2,3,4,5]
[[1,2],[3,4],[5,6]]
[[1,2,3],[4,5,6]]
[[1,2,3,4],[5,6]]
