name-me.php

$form->add('field', 'choice', array(
    'choices' => array(
        'Yes' => true,
        'No' => false,
        'Maybe' => null,
    ),
));

// $list->getValues(): ['0', '1', '2']
// $list->getChoices(): [0 => true, 1 => false 2 => null]
// $list->getThings(): [0 => 'Yes', 1 => 'No', 2 => 'Maybe']


$form->add('field', 'choice', array(
    'choices' => array(
        'Yes' => true,
        'No' => false,
        'Maybe' => null,
    ),
    'choice_value' => function ($choice, $label) {
        return strtolower($label);
    },
));

// $list->getValues(): ['yes', 'no', 'maybe']
// $list->getChoices(): ['yes' => true, 'no' => false, 'maybe' => null]
// $list->getThings(): ['yes' => 'Yes', 'no' => 'No', 'maybe' => 'Maybe']


$form->add('field', 'choice', array(
    'choices' => array($yesObj, $noObj, $maybeObj),
    'choice_value' => function ($obj) {
        return strtolower($obj->getText());
    },
    'choice_label' => function ($obj) {
        return $obj->getText();
    }
));

// $list->getValues(): ['yes', 'no', 'maybe']
// $list->getChoices(): ['yes' => $yesObj, 'no' => $noObj, 'maybe' => $maybeObj]
// $list->getThings(): ['yes' => 0, 'no' => 1, 'maybe' => 2]


$form->add('field', 'choice', array(
    'choices' => array(
        'Decided' => array($yesObj, $noObj)
        'Undecided' => array($maybeObj),
    ),
    'choice_value' => function ($obj) {
        return strtolower($obj->getText());
    },
    'choice_label' => function ($obj) {
        return $obj->getText();
    }
));

// $list->getValues(): ['yes', 'no', 'maybe']
// $list->getChoices(): ['yes' => $yesObj, 'no' => $noObj, 'maybe' => $maybeObj]
// $list->getThings(): ['yes' => 0, 'no' => 1, 'maybe' => 0]