dividing a list up to a point in prolog

Question

my_list([this,is,a,dog,.,are,tigers,wild,animals,?,the,boy,eats,mango,.]).

suppose this is a list in prolog which i want to divide in three parts that is up to three full stops and store them in variables.

how can i do that...

counthowmany(_, [], 0) :- !.
counthowmany(X, [X|Q], N) :- !, counthowmany(X, Q, N1), N is N1+1.
counthowmany(X, [_|Q], N) :- counthowmany(X, Q, N).
number_of_sentence(N) :- my_list(L),counthowmany(.,L,N).

i already counted the number of full stops in the list(my_list) now i want to divide the list up to first full stop and store it in a variable and then divide up to second full stop and store in a variable and so on.........

Answer 1

Your problem statement did not specify what a sequence without a dot should correspond to. I assume that this would be an invalid sentence - thus failure.

:- use_module(library(lambda)).

list_splitted(Xs, Xss) :-
   phrase(sentences(Xss), Xs).

sentences([]) --> [].
sentences([Xs|Xss]) -->
   sentence(Xs),
   sentences(Xss).

sentence(Xs) -->
   % {Xs = [_|_]},  % add this, should empty sentences not be allowed
   allseq(dif('.'),Xs),
   ['.'].

% sentence(Xs) -->
%    allseq(\X^maplist(dif(X),['.',?]), Xs),
%    (['.']|[?]).

allseq(_P_1, []) --> [].
allseq( P_1, [C|Cs]) -->
   [C],
   {call(P_1,C)},
   allseq(P_1, Cs).