even-odd

Even and odd

Write a function with the following type:

val is_even : int -> bool

such that is_even x is true iff x is even. Bonus: do not use the if-then-else construct.

Now, consider a simple game between two players, say A and B, with the following rules:

• A and B choose a number between 1 and 5 (any other number is considered incorrect);
• the winner is A if she played a correct number, and the sum of the two numbers is even;
• the winner is B if he played a correct number, and the sum of the two numbers is odd;
• if one player has chosen a correct number and the other has not, then the first one wins;
• if both players have chosen an incorrect number, then no one wins.

Write a function to determine the winner of the game, with type:

val win : int -> int -> int

such that win a b evaluates to:

• 1, if the first player wins (i.e., the one who played the number a);
• -1, if the second player wins;
• 0, if no one wins.