Call By Name
Call by name is a parameter-passing mechanism in programming languages where the argument expression is not evaluated before the function call, but instead is substituted directly into the function body and evaluated each time it is referenced. This contrasts with call by value, where arguments are evaluated once before the call. It is primarily used in functional and lazy-evaluation contexts, such as in the Scala programming language or in theoretical lambda calculus.
Developers should learn call by name when working with languages that support lazy evaluation or need to delay computation until necessary, such as in Scala for implementing custom control structures or avoiding unnecessary evaluations. It is useful in scenarios where arguments might be expensive to compute or have side effects that should only occur if the parameter is actually used, improving performance and enabling more expressive programming patterns like short-circuiting in logical operators.