Magician in training

import Array exposing (Array)

empty : Array Char
empty = Array.empty

singleValue = Array.fromList [ 5 ] --> Array Int

repeatSingleValue = Array.repeat 2 5 --> Array.fromList [ 5, 5 ]

initialiseFromIndex = Array.initialise 3 (\index -> index * 2) --> Array.fromList [ 0, 2, 4 ]

initialisefromList = Array.fromList [ "a", "b", "c" ] --> Array.fromList [ "a", "b", "c" ]

twoToFour = Array.fromList [ 2, 3, 4 ]
oneToFour = Array.push 1 twoToFour --> Array.fromList [ 1, 2, 3, 4 ]

sixSeven = Array.fromList [ 6, 7 ]
Array.get 0 sixSeven --> Just 6

sixSeven = Array.fromList [ 6, 7 ]
Array.set 1 8 sixSeven --> Array.fromList [ 6, 8 ]

oneTwo = Array.fromList [ 1, 2 ]
Array.length oneTwo --> 2

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