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PatternSequence[p1,p2,…]

is a pattern object that represents a sequence of arguments matching p1, p2, ….

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PatternSequence

PatternSequence[p1,p2,…]

is a pattern object that represents a sequence of arguments matching p1, p2, ….

Details

  • PatternSequence[] represents a sequence of zero length.
  • PatternSequence can appear anywhere inside a pattern but cannot be the only element of a pattern.

Examples

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Basic Examples  (2)

Replace a subsequence in a list:

Wolfram Language code: {a, b, c, d, c, d, a, b} /. {x__, PatternSequence[c, d, c], y__} -> {x, 0, y}

Match a periodic pattern:

Wolfram Language code: {a, b, a, b, a, b, a, b, a, b} /. {PatternSequence[x_, y_]..} -> x + y

Scope  (2)

A pattern with both a and an empty PatternSequence as Alternatives:

Wolfram Language code: f[a | PatternSequence[]] := x

The presence of a causes the result to be x:

Wolfram Language code: f[a]

Likewise, the empty PatternSequence matches and results in x:

Wolfram Language code: f[]

A list with just the element a or an empty list will be replaced with x:

Wolfram Language code: {{a}, {}, {a, b}} /. {a | PatternSequence[]} -> x
Wolfram Research (2007), PatternSequence, Wolfram Language function, https://reference.wolfram.com/language/ref/PatternSequence.html.

Text

Wolfram Research (2007), PatternSequence, Wolfram Language function, https://reference.wolfram.com/language/ref/PatternSequence.html.

CMS

Wolfram Language. 2007. "PatternSequence." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/PatternSequence.html.

APA

Wolfram Language. (2007). PatternSequence. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/PatternSequence.html

BibTeX

@misc{reference.wolfram_2026_patternsequence, author="Wolfram Research", title="{PatternSequence}", year="2007", howpublished="\url{https://reference.wolfram.com/language/ref/PatternSequence.html}", note=[Accessed: 12-June-2026]}

BibLaTeX

@online{reference.wolfram_2026_patternsequence, organization={Wolfram Research}, title={PatternSequence}, year={2007}, url={https://reference.wolfram.com/language/ref/PatternSequence.html}, note=[Accessed: 12-June-2026]}