Changelog

1.0.1

sort() without a comparator and sortBy() sort natively, comparing like <=>. Enums used directly as the sort key (or as the values for sort()), which <=> can't order, are now grouped by case, in an unspecified order, and placed after the other values (before them in descending order). Enums nested inside arrays are unaffected.

sortBy() and sort() are several times faster: they use PHP's native sort instead of usort() with a userland comparator.
compile() of a closure of a curried function ($curried(...)), alone or in a pipeline, keeps currying instead of throwing ArgumentCountError.
filter() on arrays with a callback taking its value by reference (fn (&$value) => ...) no longer emits "must be passed by reference" warnings.

compile() and Compilable: partials, curried and fixed functions, pipes and predicates flatten into plain closures once, so hot loops don't go through their __invoke(). Compiled internal functions drop extra arguments.
Collections in Kadet\Functional\Collections: transforms (map, filter and friends), queries, and collectors with grouping. The transforms also come lazy, returning generators, in Kadet\Functional\Collections\Lazy; queries and collectors accept lazy input and end a lazy chain.
Collection callbacks get ($value, $key), except internal functions and callables declaring one parameter, which get only the value. Wrappers (partial(), memoize(), predicates, pipe()) are seen through to the function they call.
php-ds is suggested for the collections. DsUnavailableException is thrown when it is needed but not installed.
EmptyCollectionException is thrown by queries that need an element when the collection has none (or none matching).
Docblock types and generics, so static analysis understands collection contents.

not() and Predicate::not() predicates return the negated predicate from getDecorated() instead of null.
closure() and ref() accept static method callables like [Foo::class, 'method'].