p... or RepeatedNull[p]
is a pattern object that represents a sequence of zero or more expressions, each matching p.
RepeatedNull[p,max]
represents from 0 to max expressions matching p.
RepeatedNull[p,{min,max}]
represents between min and max expressions matching p.
RepeatedNull[p,{n}]
represents exactly n expressions matching p.


RepeatedNull 
p... or RepeatedNull[p]
is a pattern object that represents a sequence of zero or more expressions, each matching p.
RepeatedNull[p,max]
represents from 0 to max expressions matching p.
RepeatedNull[p,{min,max}]
represents between min and max expressions matching p.
RepeatedNull[p,{n}]
represents exactly n expressions matching p.
Examples
open all close allBasic Examples (2)
Scope (6)
a... represents a sequence of a's inside any head:
Replace any list of a's with lengths between 0 and 3:
Replace any list of a's with lengths between 2 and 3:
Replace lists with lengths between 0 and 2 elements:
Replace lists with 0 to 3 identical elements:
Require only part of the pattern to be the same throughout the sequence:
Properties & Relations (4)
RepeatedNull[p] or p... is equivalent to RepeatedNull[p,{0,Infinity}]:
RepeatedNull[p,max] is equivalent to RepeatedNull[p,{0,max}]:
RepeatedNull[p] and RepeatedNull[p,max] allow zero repeats:
Repeated[p] and Repeated[p,max] require at least one repeat:
The forms RepeatedNull[p,{min,max}] and Repeated[p,{min,max}] are equivalent:
So are the forms RepeatedNull[p,{n}] and Repeated[p,{n}]:
Tech Notes
Related Guides
History
Introduced in 1988 (1.0) | Updated in 2007 (6.0)
Text
Wolfram Research (1988), RepeatedNull, Wolfram Language function, https://reference.wolfram.com/language/ref/RepeatedNull.html (updated 2007).
CMS
Wolfram Language. 1988. "RepeatedNull." Wolfram Language & System Documentation Center. Wolfram Research. Last Modified 2007. https://reference.wolfram.com/language/ref/RepeatedNull.html.
APA
Wolfram Language. (1988). RepeatedNull. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/RepeatedNull.html
BibTeX
@misc{reference.wolfram_2025_repeatednull, author="Wolfram Research", title="{RepeatedNull}", year="2007", howpublished="\url{https://reference.wolfram.com/language/ref/RepeatedNull.html}", note=[Accessed: 08-August-2025]}
BibLaTeX
@online{reference.wolfram_2025_repeatednull, organization={Wolfram Research}, title={RepeatedNull}, year={2007}, url={https://reference.wolfram.com/language/ref/RepeatedNull.html}, note=[Accessed: 08-August-2025]}