Lazy Evaluation

Lazy evaluation is a programming evaluation strategy that delays the computation of an expression until its value is actually needed. This contrasts with eager evaluation, where expressions are computed as soon as they are bound to variables. It is commonly used in functional programming languages and can improve performance by avoiding unnecessary calculations and enabling infinite data structures.

Also known as: Lazy Loading, Call-by-need, Deferred Evaluation, Non-strict Evaluation, Delayed Execution

Why learn Lazy Evaluation?

Developers should learn lazy evaluation when working with functional programming languages like Haskell or Scala, or when optimizing performance in data processing pipelines, such as with large datasets in Python using generators. It is particularly useful for scenarios involving potentially infinite sequences, deferred computations in UI rendering (e.g., React's lazy loading), or resource-intensive operations where on-demand evaluation saves memory and processing time.

Learning Resources

• docs: Haskell Wiki: Lazy Evaluation
• docs: MDN Web Docs: Lazy Loading
• tutorial: Real Python: Python Generators and Lazy Evaluation
• course: Coursera: Functional Programming in Scala
• video: YouTube: Lazy Evaluation Explained