Evaluation strategy

A programming language uses an evaluation strategy to determine when to evaluate the argument(s) of a function call (for function, also read: operation, method, or relation) and what kind of value to pass to the function. For example, call-by-value/call-by-reference specifies that a function application evaluates the argument before it proceeds to the evaluation of the function's body and that it passes two capabilities to the function, namely, the ability to look up the current value of the argument and to modify it via an assignment statement. The notion of reduction strategy in lambda calculus is similar but distinct.