Lazy Evaluation in Haskell Programming Language

Lazy Evaluation of Haskell Programming Language

Haskell is a functional programming language, designed for lazy evaluation. Lazy evaluation is the process of evaluating an expression only when its value is actually needed. In contrast to other languages, the order in which expressions are evaluated in Haskell is not always immediately obvious.

To explain lazy evaluation, let's first look at how a program would normally be written in a language like C. When writing C programs, you have to explicitly tell the compiler where to start execution by giving it the name of the main function. From there, the program can execute line-by-line in order, from top to bottom. This is known as eager evaluation.

In Haskell, on the other hand, the order of evaluation is determined by a set of rules defined by the language itself. These rules determine when and how certain expressions should be evaluated. For example, the language defines that if two expressions are dependent on each other, then the expression with the higher priority should be evaluated first. This prevents infinite loops and allows the programmer to express their intentions more clearly.

The lazy evaluation of Haskell has several big advantages. Firstly, it allows programs to run faster since fewer operations need to be performed. Secondly, it simplifies the programming process and makes programs easier to read and maintain. Finally, lazy evaluation can help improve the reliability of programs as it avoids the possibility of errors due to unexpected behavior.

In summary, lazy evaluation is an important concept in functional programming and is used extensively in Haskell. It helps make programs run faster, simplifies programming and improves reliability by avoiding unexpected behavior.