tarea por punto extra, Prolog

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objeto :- write('{'), read(X),(X='atributo'->atributo;
                               write('')),a1,
                               write('}').
a1:- read(X),(X='atributo'->write(','),atributo,a1;
              X='fin'->write('')).
atributo:-cadena, write(':'), valor.
valor:- read(X), (X='numero'->numero;
                  X='cadena'->cadena; 
                  X='objeto'->objeto;
                  X='metodo'->metodo).
cadena:-write('"'),read(X),write(X),write('"').
numero:- read(X),write(X).
metodo:- write('"function() {'),instruccion,write('}"').
instruccion:- read(X), (X='asignacion'->asignacion,instruccion;
                        X='condicion'->condicion,instruccion;
                        X='fin'-> write(' return '), read(Y), write(Y), write(';')).
asignacion:- numero,write('='), numero, write(';').
condicion:- read(X), (X='verdadero'->verdadero,condicion;
                      X='falso'->falso,condicion;
                      X='contenido'->contenido,condicion;
                      X='fincon'->write('}'),condicion;
                      X='fin'->write('')).
verdadero:- write('if('), read(X),write(X),write('){ ').
falso:- write('if('), read(X),write(X),write('){ ').
contenido:- read(X), write(X), write('; ').
:- objeto.

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