queues: Queue data structures.
Queue data structures, as described in
Okasaki, Chris. "Simple and efficient purely functional queues and deques." Journal of functional programming 5.4 (1995): 583-592.
Okasaki, Chris. Purely Functional Data Structures. Diss. Princeton University, 1996.
A queue has a "back" where new elements are enqueued, and a "front" where elements are dequeued in the order that they were enqueued (last in, first out).
The queues provided in this library also support an "enqueue at front" operation, because the underlying representations happen to support it, so you might technically refer to these data structures as output-restricted deques.
In this library, it is helpful to think of the "front" being on the left, because (though the direction is arbitrary) we are consistent throughout, where it matters:
List conversion functions associate the head of a list with the front of a queue.
The append operator
xs <> ys
creates a queue withxs
in front ofys
.The
Show
instances draw the front of the queue on the left.
Under "ephemeral" (or "single-threaded", or "linear") usage, wherein one does not need to refer to an old version of a data structure after mutating it:
EphemeralQueue
is 2.5x faster than and allocates 0.50x as much memory asQueue
.Queue
is 2.6x faster than and allocates 0.40x as much memory asSeq
(fromcontainers
).
(These numbers vary from benchmark to benchmark and machine to machine. Always perform your own experiments!)
While it is certainly common to use a queue ephemerally, it is unusual for a Haskell data structure to require
ephemeral usage to achieve its stated bounds. A refactoring or change in requirements might cause surprising changes
in performance. That is why EphemeralQueue
has a longer name and module name. When in doubt, use Queue
.
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Versions [RSS] | 1.0.0 |
---|---|
Change log | CHANGELOG.md |
Dependencies | base (>=4.15 && <4.21) [details] |
Tested with | ghc ==9.6.5, ghc ==9.8.2, ghc ==9.10.1 |
License | BSD-3-Clause |
Copyright | Copyright (C) 2023-2024 Mitchell Dalvi Rosen, Travis Staton |
Author | Mitchell Dalvi Rosen, Travis Staton |
Maintainer | Mitchell Dalvi Rosen <mitchellwrosen@gmail.com>, Travis Staton <hello@travisstaton.com> |
Revised | Revision 3 made by mitchellwrosen at 2024-07-10T15:22:23Z |
Category | Data |
Home page | https://github.com/awkward-squad/queues |
Bug tracker | https://github.com/awkward-squad/queues/issues |
Source repo | head: git clone https://github.com/awkward-squad/queues.git |
Uploaded | by mitchellwrosen at 2024-03-03T21:04:05Z |
Distributions | NixOS:1.0.0, Stackage:1.0.0 |
Downloads | 74 total (6 in the last 30 days) |
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Status | Docs available [build log] Last success reported on 2024-03-03 [all 1 reports] |