Issue to implement custom loss in Keras

Question

I'm trying to use in a CNN model some custom losses function like the Bce dice loss or the Tversky loss

def dsc(y_true, y_pred):
    smooth = 1.
    y_true_f = K.flatten(y_true)
    y_pred_f = K.flatten(y_pred)
    intersection = K.sum(y_true_f * y_pred_f)
    score = (2. * intersection + smooth) / (K.sum(y_true_f) + K.sum(y_pred_f) + smooth)
    return score

or

def tversky(y_true, y_pred):
    '''y_pred = ops.convert_to_tensor(y_pred)
    y_true = math_ops.cast(y_true, y_pred.dtype)'''
    y_true_pos = K.flatten(y_true)
    y_pred_pos = K.flatten(y_pred)
    true_pos = K.sum(y_true_pos * y_pred_pos)
    false_neg = K.sum(y_true_pos * (1-y_pred_pos))
    false_pos = K.sum((1-y_true_pos)*y_pred_pos)
    alpha = 0.7
    return (true_pos + smooth)/(true_pos + alpha*false_neg + (1-alpha)*false_pos + smooth)

but I'm getting this error:

true_pos = K.sum(y_true_pos * y_pred_pos)

TypeError: Value passed to parameter 'x' has DataType bool not in list of allowed values: bfloat16, float16, float32, float64, uint8, int8, uint16, int16, int32, uint32, uint64, int64, complex64, complex128

Any advice on how to fix that ?