Add API for Collections (separate package?)

[danon]

I would see it like this:

$collection = Collection::of($array);

Interface filtering

$collection->filter($pattern);
$collection->filterAny($patternList);
$collection->filterAll($patternList);

$collection->filterKeys($pattern);
$collection->filterKeysAny($patternList);
$collection->filterKeysAll($patternList);

$collection->filterAttribute($pattern, $attribute);
$collection->filterAttributeAny($patternList, $attribute);
$collection->filterAttributeAll($patternList, $attribute);

$collection->filterAssociative($pattern);
$collection->filterAssociativeAny($patternList);
$collection->filterAssociativeAll($patternList);

and same for reject.

Interface predicate

$collection->testAllSubjects($pattern);
$collection->testAnySubject($pattern);

$collection->testAllSubjectsAnyPattern($patternList);
$collection->testAnySubjectAnyPattern($patternList);

$collection->testAllSubjectsAllPatterns($patternList);
$collection->testAnySubjectAllPatterns($patternList);

and same for fail