Time to put on our detective caps: using deductive reasoning, we can make our lambda expression even shorter. Here’s what we have to start:

bool hasEvenNumbers = Array.Exists(numbers, (int num) => num % 2 == 0 );

The type of num is int. It’s great to be explicit like this to avoid errors, but some developers wouldn’t include int. To them, it’s obvious! Here’s their reasoning:

• The modulo operator (%) is only used with numbers, so num must be a number
• The result of the operation num % 2 is compared to the integer 0. We can only compare similar types, so num must also be an integer!

Therefore, we can remove int without causing any errors:

bool hasEvenNumbers = Array.Exists(numbers, (num) => num % 2 == 0 );

When there is just one parameter in a lambda expression, we don’t need the parentheses around the parameter either:

bool hasEvenNumbers = Array.Exists(numbers, num => num % 2 == 0 );

We just learned two new shortcuts “within” the lambda expression shortcut. Though we don’t need to use them all the time, we do need to recognize them in other developers’ code:

1. We can remove the parameter type if it can be inferred
2. We can remove the parentheses if there is one parameter