Magician in training

10 Points

array

Instructions

As a magician-to-be, Elyse needs to practice some basics. She has a deck of cards that she wants to manipulate.

To make things a bit easier she only uses the cards 1 to 10.

1. Retrieve a card from a deck

Implement the getCard function that returns the card at position index from the given deck. If the index is not in the deck, return Nothing.

getCard 2 ( Array.fromList [ 1, 2, 4, 1 ] )
    --> Just 4
getCard 6 ( Array.fromList [ 1, 2, 4, 1 ] )
    --> Nothing

2. Change a card in the deck

Implement the setCard function that returns a deck with the card at position index changed to the new card provided. If the index is not in the deck, return the original deck.

setCard 2 6 ( Array.fromList [ 1, 2, 4, 1 ] )
    --> Array.fromList [ 1, 2, 6, 1 ]
setCard 6 6 ( Array.fromList [ 1, 2, 4, 1 ] )
    --> Array.fromList [ 1, 2, 4, 1 ]

3. Add a card to the deck

Implement the addCard function that returns a deck with the new card added.

addCard 8 ( Array.fromList [ 5, 9, 7, 1 ] )
    --> Array.fromList [ 5, 9, 7, 1, 8 ]

4. Remove a card from the deck

Implement the removeCard function that returns a deck with the card at position index removed. If the given index is not a valid index in the deck, return the original deck.

removeCard 2 ( Array.fromList [ 3, 2, 6, 4, 8 ] )
    --> Array.fromList [ 3, 2, 4, 8 ]
removeCard 2 ( Array.fromList [ 3, 2 ] )
    --> Array.fromList [ 3, 2 ]

5. Count the number of even cards in the deck

Implement the evenCardCount function that counts the number of even cards in the deck.

evenCardCount (Array.fromList [ 3, 8, 4, 5, 1, 6, 10 ] )
    --> 4

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