A priority queue giving the highest priority to largest Ints given by your (a -> Int) function.

MaxPriorityQueue.fromList .age
    [ { name = "Martin", age = 31 }
    , { name = "Xavier", age = 13 }
    , { name = "Joanne", age = 54 }
    ]
    |> MaxPriorityQueue.largest
    --> { name = "Joanne", age = 54 }

Note that MaxPriorityQueue is not (==)-safe.

Create an empty MaxPriorityQueue.

Create a MaxPriorityQueue with a single element.

singleton identity 5
    |> toList
    --> [ 5 ]

Create a MaxPriorityQueue from a list of elements.

fromList identity [ 3, 1, 4, 1, 5, 9 ]
    |> toSortedList
    --> [ 1, 1, 3, 4, 5, 9 ]

Convert a MaxPriorityQueue to a list.

The order of items in the resulting list is unspecified. If you need a sorted list, use toSortedList.

toList (fromList identity [ 100, 3, 1, 4, 1, 5, 9, 200 ])
    --> [ 200, 100, 4, 1, 1, 9, 5, 3]

Convert a MaxPriorityQueue to a sorted list.

The order of items in the resulting list is lowest-priority-first, thus may seem reversed from what you want. See note at the top.

toSortedList (fromList identity [ 100, 3, 1, 4, 1, 5, 9, 200 ])
    --> [ 1, 1, 3, 4, 5, 9, 100, 200 ]

Fold over the elements in the MaxPriorityQueue, highest priority first.

fromList identity [ 3, 1, 4 ]
    |> fold (\x acc -> x :: acc) []
    --> [ 1, 3, 4 ]


fromList identity [ 3, 1, 4 ]
    |> fold (+) 0
    --> 8


fromList Tuple.first [ (10, "World"), (1, "Hello"), (5, "Elm") ]
    |> fold (\(_, word) acc -> acc ++ " " ++ word) ""
    --> " World Elm Hello"

Insert an element into a MaxPriorityQueue. O(log n).

empty
    |> insert identity 3
    |> insert identity 4
    |> insert identity 1
    |> largest
    --> Just 4

Insert an element into a MaxPriorityQueue. O(log n).

This is an alias for insert.

empty
    |> enqueue identity 3
    |> enqueue identity 4
    |> enqueue identity 1
    |> largest
    --> Just 4

Keep only the elements that satisfy the predicate.

fromList identity [ 1, 2, 3, 4, 5 ]
    |> filter (\x -> modBy 2 x == 0)
    |> toSortedList
    --> [ 2, 4 ]

Remove and return the element with the highest priority from the MaxPriorityQueue, along with the updated queue. Returns Nothing if the queue is empty. O(log n).

dequeue (fromList identity [ 3, 4, 1 ])
    --> Just ( 4, fromList identity [ 3, 1 ] )


dequeue empty
    --> Nothing

Retrieve the N items with highest priority, alongside the queue without them.

The order of items in the resulting list is lowest-priority-first, thus may seem reversed from what you want. See note at the top.

fromList identity [ 3, 1, 5, 2, 4 ]
    |> dequeueMany 3
    --> ( [ 3, 4, 5 ], fromList identity [ 1, 2 ] )

If you take more items than are in the queue, you will get all the items in the queue.

fromList identity [ 3, 1, 2 ]
    |> dequeueMany 5
    --> ( [ 1, 2, 3 ], empty )

Get the item with the highest priority without removing it from the queue. Returns Nothing if the queue is empty. O(1).

This is an alias for head.

largest (fromList identity [ 3, 4, 1 ])
    --> Just 4


largest empty
    --> Nothing

Get the item with the highest priority without removing it from the queue. Returns Nothing if the queue is empty. O(1).

head (fromList identity [ 3, 4, 1 ])
    --> Just 4


head empty
    --> Nothing

Get a new queue with the highest priority item removed. Returns Nothing if the queue is empty. O(log n).

tail (fromList identity [ 3, 4, 1 ])
    |> Maybe.map toSortedList
    --> Just [ 1, 3 ]


tail empty
    --> Nothing

Retrieve the N items with highest priority. O(log n).

The order of items in the resulting list is lowest-priority-first, thus may seem reversed from what you want. See note at the top.

fromList identity [ 3, 1, 5, 2, 4 ]
    |> take 3
    --> [ 3, 4, 5 ]

If you take more items than are in the queue, you will get all the items in the queue.

take 1000 (singleton identity 1)
    --> [ 1 ]

Drop the N items with highest priority from the queue. O(log n).

fromList identity [ 3, 1, 5, 2, 4 ]
    |> drop 3
    |> toSortedList
    --> [ 1, 2 ]

If you drop more items than are in the queue, you will get an empty queue.

drop 1000 (singleton identity 1)
    --> empty

Determine if all elements satisfy the predicate.

fromList identity [ 1, 2, 3 ]
    |> all (\x -> x > 10)
    == False


fromList identity [ 9, 11 ]
    |> all (\x -> x > 10)
    == False


fromList identity [ 15, 16, 17 ]
    |> all (\x -> x > 10)
    == True


all (\_ -> True) empty --> True


all (\_ -> True) (singleton identity 1) --> True


all (\_ -> False) empty --> True


all (\_ -> False) (singleton identity 1) --> False

Determine if any elements satisfy the predicate.

fromList identity [ 1, 2, 3 ]
    |> any (\x -> x > 10)
    == False


fromList identity [ 9, 11 ]
    |> any (\x -> x > 10)
    == True


fromList identity [ 15, 16, 17 ]
    |> any (\x -> x > 10)
    == True


any (\_ -> True) empty --> False


any (\_ -> True) (singleton identity 1) --> True


any (\_ -> False) empty --> False


any (\_ -> False) (singleton identity 1) --> False

Check if a MaxPriorityQueue is empty.

isEmpty empty
    --> True


isEmpty (singleton identity 1)
    --> False

Get the number of elements in the queue. O(1).

length (fromList identity [ 1, 2, 3 ])
    --> 3


length empty
    --> 0