KeyValuePattern lets you match any element in an association:

It also works on lists of rules:

KeyValuePattern matches elements that appear anywhere in an association:

Match any association with two entries:

KeyValuePattern distinguishes Rule and RuleDelayed:

Extract the key from an Association that matches a rule:

Extract a rule based on a condition:

Every rule in Association is matched at most once:

A single pattern in KeyValuePattern does not need to be in a List:

An empty KeyValuePattern matches any association or list of rules:

Apply a filter to a list of associations:

This works similarly to the following:

KeyValuePattern matches in any order:

A pattern containing an Association matches rules in exact order:

An expression matched by KeyValuePattern may contain other rules besides those specified:

A pattern containing an Association will attempt to match against all rules:

BlankNullSequence in KeyValuePattern matches only a single rule:

In a pattern containing an Association, BlankNullSequence may match more than one rule:

Every pattern in KeyValuePattern may match only one rule:

Empty list or Association can be matched by BlankNullSequence or RepeatedNull patterns:

KeyValuePattern matches only an Association or a list of rules, even if no patterns are specified:

KeyValuePattern will not match RuleDelayed if Rule is specified: