Seminario_TP3_EJ03

(defun listar_alumn_todas_mat (l)

    (defun existe (a l)
        (if (null l) nil
            (if (string= a (car l)) t
                (existe a (cdr l))
            )
        )
    )

    (defun guardoMat (l l2)
        (if (null (cdr l)) l2
            (if (existe (cadr l) l2) (guardoMat (cdr l) l2)
                (guardoMat (cdr l) (append l2 (list (cadr l))))
            )
        )
    )
    (defun listaMat (l &optional (salida nil))
        (if (null l) salida
            (listaMat (cdr l) (guardoMat (car l) salida))
        )
    )

    (defun alumnMat (l materia)
        (if (null l) nil
            (if (existe materia (car l))
                (append (list (caar l)) (alumnMat (cdr l) materia))
                (alumnMat (cdr l) materia)
            )
        )
    )
    (defun alumnTodasMat (l mats)
        (if (null mats) nil
            (append (list (cons (car mats) (list (alumnMat l (car mats)))))
                (alumnTodasMat l (cdr mats)))
        )
    )

    (alumnTodasMat l (listaMat l))
)