What is lazy evaluation in Haskell and how does it work?

What is lazy evaluation in Haskell and how does it work?

Lazy evaluation is a programming technique where expressions are not evaluated until their values are needed. In Haskell, this allows for efficient memory usage and the ability to work with infinite data structures.

Can you give me an example of lazy evaluation in action?

Sure! Consider the following code: let xs = [1..] creates an infinite list of integers. If you use take 5 xs, Haskell only evaluates the first five elements, demonstrating lazy evaluation.

What are the benefits of using lazy evaluation?

The benefits include improved performance by avoiding unnecessary calculations, the ability to define potentially infinite data structures, and better modularity in code.

Are there any downsides to lazy evaluation?

Yes, it can lead to increased memory usage if not managed properly, as unevaluated expressions accumulate. It may also introduce complexity in reasoning about performance.