%first element of a list
%first(F,L).
%first(F,[F|L]).

%?-first(0,[1,2,3]).
%-----------------------

%is an element a member of a list
%member(X,[X|L]).
%member(X,[F|L]):-member(X,L).

%?-member(3,[1,2,3]).
%-----------------------

%is the given argument is a list
%list([]).
%list([X|L]):-list(L).

%?-list([]).
%-----------------------

%is N the length of L
%length(0,[]).
%length(N,[_|L]):-length(M,L),N is M+1.

%?-length(4,[1,2,3,4]).
%-----------------------

%is the given element the last of the list
%last(F,[F|[]]).
%last(F,[X|T]):-last(F,T).

%?-last(1,[3,2,1]).
%-----------------------

%is the given element before the last one in the list
%beforelast(F,[F,A|[]]).
%beforelast(F,[_|T]):- beforelast(F,T).

%?-beforelast(1,[3,2,1,0]).
%-----------------------

%is the given element X, the N-th in the list L
%nelement(X,N,L).
%nelement(X,0,[X|_]).
%nelement(X,M,[_|L]):- M>0, N is M-1,nelement(X,N,L).

%?-nelement(3,0,[3,2,1,0]).
%-----------------------

%minimal element in list
min(X,[X]).
min(X,[H|T]):-min(X,T),X<H.

%?-min(0,[5,3,2,1,0]).
%-----------------------

%remove the given element H of L and the result is L1
%remove(H,L,L1).
remove(H, [H|T] , T).
remove(H,[X|T],[X,T1]):-remove(H,T,T1).

%?-remove(1,[1,2,3,4],[2,3,4]).
%-----------------------

%append the given B after A == AB.
%append(A,B,AB).
append([],B,B).
append([H|T],B,[H|C]):- append(T,B,C).

?-append([1,2],[3,4],[1,2,3,4]).