RuleDelayed

lhs:>rhs or lhsrhs

represents a rule that transforms lhs to rhs, evaluating rhs only after the rule is used.

Details

Examples

open allclose all

Basic Examples  (1)

:> holds its right-hand side unevaluated:

The right-hand side is evaluated separately each time it is used:

Applications  (3)

Increment n each time x is replaced:

Evaluate the StepMonitor expression separately each time it is to be used:

Generate a diagonal matrix with random elements:

Properties & Relations  (6)

-> evaluates when it is first entered; :> when it is used:

Module and With do not affect local variables of RuleDelayed:

Module effectively uses a renamed instance of y:

By evaluating the arguments to RuleDelayed, local scoping is avoided:

KeyValuePattern can be used to transform a list of rules:

KeyValuePattern distinguishes between Rule and RuleDelayed:

Wolfram Research (1988), RuleDelayed, Wolfram Language function, https://reference.wolfram.com/language/ref/RuleDelayed.html (updated 1996).

Text

Wolfram Research (1988), RuleDelayed, Wolfram Language function, https://reference.wolfram.com/language/ref/RuleDelayed.html (updated 1996).

CMS

Wolfram Language. 1988. "RuleDelayed." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 1996. https://reference.wolfram.com/language/ref/RuleDelayed.html.

APA

Wolfram Language. (1988). RuleDelayed. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/RuleDelayed.html

BibTeX

@misc{reference.wolfram_2021_ruledelayed, author="Wolfram Research", title="{RuleDelayed}", year="1996", howpublished="\url{https://reference.wolfram.com/language/ref/RuleDelayed.html}", note=[Accessed: 09-December-2021 ]}

BibLaTeX

@online{reference.wolfram_2021_ruledelayed, organization={Wolfram Research}, title={RuleDelayed}, year={1996}, url={https://reference.wolfram.com/language/ref/RuleDelayed.html}, note=[Accessed: 09-December-2021 ]}