Lambda or Proc.new in Ruby? Choosing the Right One for Your Code

When it comes to defining anonymous functions in Ruby, there are two popular options: lambda and Proc.new. While they may seem similar at first glance, there are some important differences that can impact which one you choose for your code.

What is a lambda?
A lambda is a type of anonymous function that is created using the lambda keyword. One key characteristic of a lambda is that it enforces strict arity, or the number of arguments that can be passed to it. This means that if you try to pass too many or too few arguments to a lambda, it will raise an error.

What is a Proc.new?
A Proc.new, also known as a Proc, is another type of anonymous function in Ruby. Unlike a lambda, a Proc does not enforce strict arity. This means that you can pass any number of arguments to a Proc without raising an error.

Which one should you choose?
The decision between using a lambda or Proc.new ultimately depends on your specific use case. If you need to enforce strict arity and ensure that a specific number of arguments are always passed to your function, then a lambda is likely the better choice. On the other hand, if you need more flexibility in the number of arguments that can be passed, a Proc.new may be the way to go.

It's worth noting that lambdas also have a slightly different syntax for defining arguments, using the -> arrow instead of the . dot notation used with Proc.new. Additionally, lambdas are considered to be more "pure" functions, as they have a more strict return behavior.

In summary, both lambdas and Proc.new have their own unique characteristics and use cases. By understanding the differences between the two, you can choose the right one for your specific coding needs.