MatchQ

Whether expr matches pattern, at the top level.

✓ checked against that system · ! checked, with disagreements (hover a chip)Wolfram LanguageMatchQ!↗

MatchQ(expr, pattern)True if expr matches pattern, False otherwise

Typed signatures

Type	Package	Applies
(any, any) -> boolean	combinatorics	always

Domain: Collections

Details

• Built directly on compute-engine's own wildcard grammar (BoxedExpression.match): _/_name matches one element, __/__name one-or-more, ___/___name zero-or-more — Wolfram's Blank/BlankSequence/BlankNullSequence, unnamed or named.
• There is no head-restricted blank (Wolfram's _Integer): a wildcard binds to whatever it lands on, with no type filter. Pattern/Optional (x_:default) and condition patterns (_?test) aren't implemented either.

Examples

Basic #

live ↗

In$\mathrm{MatchQ}(x+1, \operatorname{\_a}+\operatorname{\_b})$Out$\mathrm{True}$

Matching is structural: $1 + 1/\varphi - \varphi = 0$, yet it doesn't match $0$

live ↗

In$\mathrm{MatchQ}(1+\frac{1}{\varphi}-\varphi, 0)$Out$\mathrm{False}$

Scope #

live ↗

In$\mathrm{MatchQ}(xy, \operatorname{\_a}+\operatorname{\_b})$Out$\mathrm{False}$

__rest (a sequence wildcard) absorbs one or more trailing elements

live ↗

In$\mathrm{MatchQ}(\bigl\lbrack1, 2, 3\bigr\rbrack, \bigl\lbrack\operatorname{\_a}, \operatorname{\_\_rest}\bigr\rbrack)$Out$\mathrm{True}$

About

Examples	5
Checked against	Wolfram Language 1 agree1 differ
Crosswalk	Wolfram Language

See also: FreeQ, Replace