phone.pl

/*  File: phone.pl  Author: Mihaela Malita
    Title: Transforms phone numbers written with digits in words.
*/
/*  a -97  e-101  i- 105 o-111 u-117 y-121  ?- two_vowels(soap).
    vowel(V) :- member(V,[97,101,105,111,117,121]).
    two_vowels(Word) :- atom_codes(Word,Lw), append(_,[V1,V2|_],Lw), vowel(V1), vowel(V2).
*/

:- encoding(utf8).
:- use_module(library(lists)).

key(1,[1]).
key(2,[a,b,c]).
key(3,[d,e,f]).
key(4,[g,h,i]).
key(5,[j,k,l]).
key(6,[m,n,o]).
key(7,[p,r,s]).
key(8,[t,u,v]).
key(9,[w,x,y]).
key(0,[0]).

phone([],[]).
phone([N|T],[X|R]) :-
	key(N,Letters),
	member(X,Letters),
	phone(T,R).
/* same as
possible(D,Let) :- key(D,L),member(Let,L).
?- possible(2,F).
F = a ;
F = b ;
F = c.
?- maplist(possible,[1,2,3],R).
R = [1, a, d] ; R = [1, a, e] ; R = [1, a, f] ; R = [1, b, d] ;
R = [1, b, e] ; R = [1, b, f] ; R = [1, c, d] ; R = [1, c, e] ;
R = [1, c, f].
phone2(P,R) :- findall(S,maplist(possible,[1,2,3],S),R).
***************************************************************/
/*
start :- write('your phone as a list(ex:[4,3,6,6]? '),read(Phone),
	(phone(Phone,L),write(L),nl,false).
*/
vowel(a).  vowel(e).  vowel(i).  vowel(o).  vowel(u).  vowel(y).

/* has_vowels([m,a,r,y]),2).  */
has_vowels([],0).
has_vowels([H|T],N) :-
	vowel(H),
	has_vowels(T,K),
	N is K+1, !.
has_vowels([_|T],N) :- has_vowels(T,N).

start :-
	write('Your phone as a list (ex: [4,3,6,6] = '),
	read(Phone),
	(phone(Phone,L),
	 (has_vowels(L,2),
	  write(L), nl ;
	  true),
	 false).

/*  Discussion. How many possiblities there are?
    Improve program using name/2.
*/