/*
   Turbo Prolog 2.0 Chapter 18, Example Program 6
   
   Copyright (c) 1986, 88 by Borland International, Inc
*/   

domains
    letter = char
    word = letter*

predicates
    divide(word, word, word, word)
    vocal(letter)
    consonant(letter)
    string_word(string, word)
    append(word, word, word)
    repeat

goal
    clearwindow,
    repeat,
    write("Write a multi-syllable word: "),
    readln(S),
    string_word(S, Word),
    divide([], Word, Part1, Part2),
    string_word(Syllable1, Part1),
    string_word(Syllable2, Part2),
    write("Division: ",Syllable1,"-",Syllable2),nl,
    fail.

clauses
    divide(Start, [T1, T2, T3|Rest], D1, [T2, T3|Rest]):-
        vocal(T1), consonant(T2), vocal(T3),
        append(Start, [T1], D1).
    divide(Start, [T1, T2, T3, T4|Rest], D1,[T3, T4|Rest]):-
        vocal(T1), consonant(T2), consonant(T3), vocal(T4),
        append(Start, [T1, T2], D1).
    divide(Start, [T1|Rest], D1, D2):-
        append(Start, [T1], S),
        divide(S, Rest, D1, D2).

    vocal('a').vocal('e').vocal('i').
    vocal('o').vocal('u').vocal('y').

    consonant(B):-
        not(vocal(B)), B <= 'z', 'a' <= B.

    string_word("", []):-!.
    string_word(Str, [H|T]):-
        bound(Str), frontchar(Str, H, S), string_word(S, T).
    string_word(Str, [H|T]):-
        free(Str), bound(H), string_word(S, T),
        frontchar(Str,H,S).

    append([], L, L):-!.
    append([X|L1], L2, [X|L3]) :-
        append(L1, L2, L3).

    repeat.
    repeat :- repeat.