wiki143 - User contributions [en]

Type erasure

2024-01-15T19:16:38Z

85.64.76.29: /* See also */Added wiki link to monomorphization.

{{Short description|Process by which explicit type annotations are removed from a program}}
In [[programming languages]], '''type erasure''' is the [[Loader (computing)|load-time]] process by which explicit [[Type_signature|type annotations]] are removed from a program, before it is executed at [[Run time (program lifecycle phase)|run-time]]. [[Operational semantics]] not requiring programs to be accompanied by types are named ''type-erasure semantics'', in contrast with ''type-passing semantics''. Type-erasure semantics is an [[Abstraction principle (computer programming)|abstraction principle]], ensuring that the run-time execution of a program doesn't depend on type information. In the context of [[generic programming]], the opposite of type erasure is named [[Reification (computer science)|reification]].<ref>{{cite web|last1=Langer|first1=Angelika|title=What is reification?|url=http://www.angelikalanger.com/GenericsFAQ/FAQSections/TechnicalDetails.html#FAQ101A}}</ref>

== Type inference ==
{{Main|Type inference}}
The reverse operation is named [[type inference]]. Though type erasure can be an easy way to define typing over implicitly typed languages (an implicitly typed term is well-typed [[if and only if]] it is the erasure of a well-typed explicitly typed [[lambda term]]), it doesn't provide [[rules of inference|Rule of inference]] for this definition.

==See also==
* [[Template (C++)]]
* [[Generics in Java#Problems with type erasure|Problems with type erasure]] (in [[Generics in Java]])
* [[Monomorphization]]
* [[Type polymorphism]]

==References==
{{Reflist}}
* {{cite journal
| first1 = Karl | last1 = Crary
| first2 = Stephanie | last2 = Weirich | author2-link= Stephanie Weirich
| first3 = Greg | last3 = Morrisett
| title = Intensional Polymorphism in Type-Erasure Semantics
| journal = Journal of Functional Programming
| volume = 12
| issue = 6
| pages = 567–600
|doi = 10.1017/S0956796801004282
| year = 2002
| citeseerx = 10.1.1.5.4507
}}

[[Category:Type theory]]

{{comp-sci-stub}}

Dar (disk archiver)

2023-09-14T16:45:59Z

85.64.76.29: /* See also */ Added FSArchiver — like dar, it works with files instead of filesystem blocks, and allows restoration to smaller targets.

{{Multiple issues|{{notability|Products|date=January 2019}}
{{Citation style|date=June 2018}}}}

{{Infobox software
| name = dar
| logo =
| screenshot =
| caption =
| developer =
| released = {{Start date and age|2002|02|02|df=yes}}<ref>{{cite web|url=http://dar.linux.free.fr/dar_ten.html|title=DAR - Disk ARchive has 10 Years!|website=dar.linux.free.fr}}</ref>
| latest release version = {{wikidata|property|preferred|references|edit|Q3011110|P348|P548=Q2804309}}
| latest release date = {{wikidata|qualifier|preferred|single|Q3011110|P348|P548=Q2804309|P577}}
| latest preview version = {{wikidata|property|preferred|references|edit|Q3011110|P348|P548=Q51930650}}
| latest preview date = {{wikidata|qualifier|preferred|single|Q3011110|P348|P548=Q51930650|P577}}
| genre = Data compression
| license = [[GNU General Public License|GPL-2.0-or-later]]
| website = {{URL|dar.linux.free.fr}}
| repo = {{URL|https://sourceforge.net/projects/dar/|DAR Repository}}
| operating_system = {{plainlist|
* [[Linux]]
* [[Microsoft Windows|Windows]]
* [[Solaris (operating system)|Solaris]]
* [[FreeBSD]]
* [[NetBSD]]
* [[macOS]]<ref>{{cite web|accessdate=2019-01-05|title=DAR - Disk ARchive|url=http://dar.linux.free.fr/|website=dar.linux.free.fr}}</ref>
}}
}}
'''dar''' ('''d'''isk '''ar'''chive) is a [[computer program]], a command-line archiving tool<ref>{{cite web|url=http://dar.linux.free.fr/doc/|title=Dar's Documentation|website=dar.linux.free.fr}}</ref> intended as a replacement for [[tar (file format)|tar]] in [[Unix-like]] [[operating system]]s.{{Citation needed|date=June 2018}}

== Features ==
{{prose|section|date=January 2019}}
* Support for slices, archives split over multiple files of a particular size
* Option of deleting files from the system which are removed in the archive
* [[Backup|Full backup]]
* [[Differential backup]]
* [[Incremental backup]],
* Decremental backup
* Takes care of any type of [[inode]] (directory, plain files, [[Symbolic link|symlinks]], [[Device file|special devices]], [[named pipe]]s, [[Unix domain socket|sockets]], [[Doors (computing)|doors]], ...)
* Takes care of [[Hard link|hard-linked]] inodes (hard-linked plain files, [[Character device|char devices]], [[block device]]s, hard-linked symlinks)
* Takes care of [[sparse file]]s
* Takes care of Linux file [[Extended file attributes|Extended Attributes]],
* Takes care of Linux file [[Access-control list|ACL]]
* Takes care of Mac OS X [[Resource fork|file forks]]
* Takes care of some filesystem specific attributes like Birthdate of [[HFS Plus|HFS+ filesystem]] and immutable, [[Journaling file system|data-journaling]], [[Data erasure|secure-deletion]], [[Block suballocation|no-tail-merging]], undeletable, noatime attributes of ext2/3/4 filesystem.
* Per-file compression with [[gzip]], [[bzip2]], [[lzo]], [[XZ Utils|xz]] or [[lzma]] (as opposed to compressing the whole archive). An individual can choose not to compress already compressed files based on their filename suffix.
* Fast-extracting of files from anywhere in the archive
* Fast listing of archive contents through saving the catalogue of files in the archive
* Optional [[Blowfish (cipher)|Blowfish]], [[Twofish]], [[Advanced Encryption Standard|AES]], [[Serpent (cipher)|Serpent]], [[Camellia (cipher)|Camellia]] encryption
* Optional public key encryption and signature ([[OpenPGP]])
* Live filesystem backup: detects when a file has been modified while it was read for backup and can retry saving it up to a given maximum number of retries
* [[Hash function|Hash]] file ([[MD5]], [[SHA-1|SHA1]] or [[SHA-512]]) generated on-fly for each slice, the resulting file is compatible with <code>md5sum</code> or <code>sha1sum</code>, to be able to quickly check each slice's integrity
* Filesystem independent: it may be used to restore a system to a partition of a different size and/or to a partition with a different filesystem<ref>{{cite web|url=http://dar.linux.free.fr/doc/Tutorial.html|title=DAR - Tutorial|website=dar.linux.free.fr}}</ref>

== Frontends ==
There are GUI frontends for dar called:
* Kdar for Linux, specifically [[KDE Plasma Workspaces|KDE]],
* DarGUI for Linux and Windows,
* gdar for Linux.
A text-mode browser/extractor: plugin for dar files in mc ([[Midnight Commander]]).

A scheduler / command-line frontend known as SaraB allows the [[Backup rotation scheme#Tower of Hanoi|Towers of Hanoi]], [[Grandfather-Father-Son Backup|Grandfather-Father-Son]], or any custom [[Backup rotation scheme|backup rotation]] strategy, and modifications are available for [[Parchive|PAR]] file support. Extended versions known as bzSaraB and baras are also available.

== See also ==
{{Portal|Free and open-source software}}
* [[FSArchiver]]
* [[List of file archivers]]
* [[List of archive formats]]
* [[Comparison of archive formats]]

==References==
{{Reflist}}

== External links ==
* [http://dar.linux.free.fr/ Homepage of dar]

{{Archive formats}}

[[Category:2002 software]]
[[Category:Free data compression software]]
[[Category:Free backup software]]

Cache Array Routing Protocol

2022-05-29T13:47:46Z

85.64.76.29: Simplify hatnote.

{{HTTP}}
{{Distinguish|Common Address Redundancy Protocol}}
The '''Cache Array Routing Protocol''' (CARP) is used in load-balancing [[HTTP]] requests across multiple proxy cache servers. It works by generating a hash for each URL requested. A different hash is generated for each URL and by splitting the hash namespace into equal parts (or unequal parts if uneven load is intended) the overall number of requests can be distributed to multiple servers.

Implementations include [[Apache Traffic Server]], [[Squid (software)]] and the [[Microsoft Internet Security and Acceleration Server]] as well as [[F5 Networks|F5 Networks BIG-IP devices]].

== External links ==
*[https://tools.ietf.org/html/draft-vinod-carp-v1-03 Cache Array Routing Protocol v1.0 draft]

{{web-stub}}
[[Category:Hypertext Transfer Protocol]]