Used in this article: https://medium.com/@bgoetzmann/modèle-de-conception-commande-en-langage-groovy-9bea26b47d6

UseReceiverInHighOrderFunctionsForCommands.groovy

def _makeAddItemCommand(Item item) {
    { Cart cart -> cart.addItem(item) }
}

def _makeRemoveItemCommand(Item item) {
    { Cart cart -> cart.removeItem(item) }
}

def actions = [
    _makeAddItemCommand(new Item(name: 'Item1', price: 1)),
    _makeAddItemCommand(new Item(name: 'Item2', price: 1)),
    _makeRemoveItemCommand(new Item(name: 'Item1', price: 1))
]

def _fpCart = new Cart()
actions*.call(_fpCart)

assert _fpCart.items.keySet() == ['Item2'] as Set