{"id":55281,"date":"2020-01-17T00:00:00","date_gmt":"2020-01-16T21:00:00","guid":{"rendered":"https:\/\/prohoster.info\/blog\/blog_prohoster\/chto-sdelalo-lisp-osobennym"},"modified":"2020-02-18T14:03:23","modified_gmt":"2020-02-18T11:03:23","slug":"chto-sdelalo-lisp-osobennym","status":"publish","type":"post","link":"https:\/\/prohoster.info\/da\/blog\/news\/chto-sdelalo-lisp-osobennym","title":{"rendered":"Hvad der gjorde Lisp specielt","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\u00abDet st\u00f8rste programmeringssprog, der nogensinde er skabt<\/i>\u00ab
\n \u2014 Alan Kay, \u00abon Lisp\u00bb<\/p><\/blockquote>\n

\n\"Hvad
\n
\nDa McCarthy udviklede Lisp i slutningen af 1950'erne, adskilte det sig radikalt fra de eksisterende sprog, hvoraf det vigtigste var Fortran<\/a><\/noindex>.
\n<\/a><\/noindex>
\nLisp inkorporerede ni nye id\u00e9er:<\/p>\n

1. Betingede udsagn (Conditionals)<\/b>. Betingede udsagn er en if-then-else-konstruktion. I dag tager vi dem for givet. De blev opfundet<\/a><\/noindex> af McCarthy under udviklingen af Lisp. (Fortran havde p\u00e5 det tidspunkt kun goto-erkl\u00e6ringer, der var t\u00e6t knyttet til den underliggende hardware's betingede instruktioner.) McCarthy, der var i Algol-komit\u00e9en, introducerede betingede udsagn i Algol, hvorfra de spredte sig til andre sprog.<\/p>\n

2. Funktionstyper (A function type)<\/b>. I Lisp er funktioner objekter af f\u00f8rste klasse \u2014 de er datatyper ligesom tal, strenge osv. og har et bogstaveligt repr\u00e6sentation, kan gemmes i variable, kan overf\u00f8res som argumenter osv. <\/p>\n

3. Rekursion (Recursion)<\/b>. Rekursion eksisterede naturligvis som et matematisk koncept f\u00f8r Lisp, men Lisp var det f\u00f8rste programmeringssprog, der underst\u00f8ttede det. (Dette implikeres m\u00e5ske af oprettelsen af funktioner som objekter af f\u00f8rste klasse.)<\/p>\n

4. Ny koncept for variabler (A new concept of variables)<\/b>. I Lisp er alle variable effektive pegevariable. V\u00e6rdier er det, som findes hos typerne, og ikke hos de variable, og tildeling eller binding af variable betyder at kopiere pegevariable, ikke det, de peger p\u00e5.<\/p>\n

5. Affaldssamling (Garbage-collection)<\/b>.<\/p>\n

6. Programmer sammensat af udtryk (Programs composed of expressions)<\/b>. Programmer i Lisp er udtrykstr\u00e6er, hvor hvert udtryk returnerer en v\u00e6rdi. (Nogle Lisp-udtryk kan returnere flere v\u00e6rdier.) Dette st\u00e5r i kontrast til Fortran og mange andre succesfulde sprog, der adskiller \"udtryk\" og \"udsagn.\"<\/p>\n

Det var naturligt at have en s\u00e5dan adskillelse i Fortran, fordi sproget var linj\u00e6rt orienteret (ikke overraskende for et sprog, hvor inputformatet var kortb\u00e5nd). Du kunne ikke have indlejrede udsagn. Og mens du havde brug for matematiske udtryk til at arbejde med, var der ikke nogen mening i at f\u00e5 noget andet til at returnere en v\u00e6rdi, da der m\u00e5ske ikke var noget, der forventede et return.<\/p>\n

Begr\u00e6nsningerne blev fjernet med fremkomsten af block-strukturerede sprog, men p\u00e5 det tidspunkt var det allerede for sent. Forskellen mellem udtryk og udsagn var allerede etableret. Det gik fra Fortran til Algol og videre til deres efterkommere.<\/p>\n

N\u00e5r et sprog er helt sammensat af udtryk, kan du danne udtryk som du \u00f8nsker. Du kan skrive enten (ved at bruge syntaks\u00a0Arc<\/a><\/noindex>)<\/p>\n

(if foo (= x 1) (= x 2))<\/code><\/pre>\n
\neller<\/p>\n
(= x (if foo 1 2))<\/code><\/pre>\n
\n7. Symboltype<\/b>. Symboler adskiller sig fra strenge, i dette tilf\u00e6lde kan du tjekke for lighed ved at sammenligne pegere.<\/p>\n
8. Notation for kode<\/b> ved at bruge tr\u00e6er af symboler.<\/p>\n
9. Hele sproget er altid tilg\u00e6ngeligt.<\/b>. Der er ingen \u00e5benlys forskel mellem l\u00e6setid, kompileringstid og k\u00f8retid. Du kan kompilere eller k\u00f8re kode under l\u00e6sning, eller l\u00e6se eller k\u00f8re kode mens du kompilere, eller l\u00e6se eller kompilere kode under k\u00f8rslen.<\/p>\n
K\u00f8rsel af kode under l\u00e6sning tillader brugere at omprogrammere syntaksen i Lisp; k\u00f8rsel af kode under kompilering er grundlaget for makroer; kompilering under udf\u00f8relse er grundlaget for at bruge Lisp som udvidelsessprog i programmer som Emacs; og endelig tillader l\u00e6sning under udf\u00f8relse programmer at interagere ved hj\u00e6lp af s-udtryk, en id\u00e9, der for nyligt er genopfundet i XML.<\/p>\n
Konklusion<\/h4>\n
\nDa Lisp blev opfundet, var alle disse ideer langt fra almindelig programmeringspraksis, som blev dikteret af det hardware, der var tilg\u00e6ngeligt i slutningen af 1950'erne.<\/p>\n
Over time, the default language, embodied in the success of popular languages, has gradually evolved towards Lisp. Points 1-5 are now widely common. Point 6 is starting to emerge in the mainstream. In Python, there is some form of point 7, although there is no suitable syntax. Point 8, which (along with point 9) makes macros in Lisp possible, still only exists in Lisp, possibly because (a) it requires those parentheses or something equally unappealing, and (b) if you add this last increase in power, you can no longer claim to have invented a new language, but rather developed a new dialect of Lisp; -)<\/p>\n
Although it is helpful for modern programmers, it is strange to describe Lisp in terms of its differences from random techniques adopted in other languages. Perhaps this is not what McCarthy had in mind. Lisp was not designed to fix Fortran's errors; it emerged more as a byproduct of an attempt at axiomatiskg\u00f8re beregninger<\/a><\/noindex>.
\n
Kilde: habr.com<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"
«\u0412\u0435\u043b\u0438\u0447\u0430\u0439\u0448\u0438\u0439 \u0438\u0437 \u043a\u043e\u0433\u0434\u0430-\u043b\u0438\u0431\u043e \u0441\u043e\u0437\u0434\u0430\u043d\u043d\u044b\u0445 \u044f\u0437\u044b\u043a\u043e\u0432 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f« \u2014 Alan Kay, \u00abon Lisp\u00bb \u041a\u043e\u0433\u0434\u0430 \u041c\u0430\u043a\u043a\u0430\u0440\u0442\u0438 \u0440\u0430\u0437\u0440\u0430\u0431\u043e\u0442\u0430\u043b Lisp \u0432 \u043a\u043e\u043d\u0446\u0435 1950-\u0445, \u043e\u043d \u0440\u0430\u0434\u0438\u043a\u0430\u043b\u044c\u043d\u043e \u043e\u0442\u043b\u0438\u0447\u0430\u043b\u0441\u044f \u043e\u0442 \u0441\u0443\u0449\u0435\u0441\u0442\u0432\u0443\u044e\u0449\u0438\u0445 \u044f\u0437\u044b\u043a\u043e\u0432, \u0441\u0430\u043c\u044b\u043c \u0433\u043b\u0430\u0432\u043d\u044b\u043c \u0438\u0437 \u043a\u043e\u0442\u043e\u0440\u044b\u0445 \u0431\u044b\u043b Fortran. Lisp \u0432\u043e\u043f\u043b\u043e\u0442\u0438\u043b \u0434\u0435\u0432\u044f\u0442\u044c \u043d\u043e\u0432\u044b\u0445 \u0438\u0434\u0435\u0439: 1. \u0423\u0441\u043b\u043e\u0432\u043d\u044b\u0435 \u0432\u044b\u0441\u043a\u0430\u0437\u044b\u0432\u0430\u043d\u0438\u044f (Conditionals).\u00a0\u0423\u0441\u043b\u043e\u0432\u043d\u044b\u0435 \u0432\u044b\u0441\u043a\u0430\u0437\u044b\u0432\u0430\u043d\u0438\u044f \u044d\u0442\u043e if-then-else \u043a\u043e\u043d\u0441\u0442\u0440\u0443\u043a\u0446\u0438\u044f. \u0421\u0435\u0439\u0447\u0430\u0441 \u043c\u044b \u0432\u043e\u0441\u043f\u0440\u0438\u043d\u0438\u043c\u0430\u0435\u043c \u0438\u0445 \u043a\u0430\u043a \u0434\u043e\u043b\u0436\u043d\u043e\u0435. \u041e\u043d\u0438 \u0431\u044b\u043b\u0438 \u0438\u0437\u043e\u0431\u0440\u0435\u0442\u0435\u043d\u044b \u041c\u0430\u043a\u043a\u0430\u0440\u0442\u0438 \u0432\u043e \u0432\u0440\u0435\u043c\u044f […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":55282,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-55281","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47Hvad der gjorde Lisp s\u00e6rligt | ProHoster","description":"\"Den st\u00f8rste af alle programmeringssprog, der nogensinde er lavet\" \u2014 Alan Kay, \u00abon Lisp\u00bb","canonical_url":"https:\/\/prohoster.info\/da\/blog\/news\/chto-sdelalo-lisp-osobennym","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"da_DK","og:site_name":"ProHoster | \u041a\u0443\u043f\u0438\u0442\u044c \u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0439 \u0445\u043e\u0441\u0442\u0438\u043d\u0433 \u0434\u043b\u044f \u0441\u0430\u0439\u0442\u043e\u0432 \u0441 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 \u043e\u0442 DDoS, VPS VDS \u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47\u0427\u0442\u043e \u0441\u0434\u0435\u043b\u0430\u043b\u043e Lisp \u043e\u0441\u043e\u0431\u0435\u043d\u043d\u044b\u043c | ProHoster","og:description":""\u0412\u0435\u043b\u0438\u0447\u0430\u0439\u0448\u0438\u0439 \u0438\u0437 \u043a\u043e\u0433\u0434\u0430-\u043b\u0438\u0431\u043e \u0441\u043e\u0437\u0434\u0430\u043d\u043d\u044b\u0445 \u044f\u0437\u044b\u043a\u043e\u0432 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u044f" \u2014 Alan Kay, \u00abon Lisp\u00bb","og:url":"https:\/\/prohoster.info\/da\/blog\/news\/chto-sdelalo-lisp-osobennym","og:image":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:secure_url":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:width":350,"og:image:height":350,"article:published_time":"2020-01-16T21:00:00+00:00","article:modified_time":"2020-02-18T11:03:23+00:00","article:publisher":"https:\/\/www.facebook.com\/prohoster","article:author":"https:\/\/www.facebook.com\/prohoster"},"aioseo_meta_data":{"post_id":"55281","title":null,"description":null,"keywords":null,"keyphrases":null,"primary_term":null,"canonical_url":null,"og_title":null,"og_description":null,"og_object_type":"default","og_image_type":"default","og_image_url":null,"og_image_width":null,"og_image_height":null,"og_image_custom_url":null,"og_image_custom_fields":null,"og_video":null,"og_custom_url":null,"og_article_section":null,"og_article_tags":null,"twitter_use_og":false,"twitter_card":"default","twitter_image_type":"default","twitter_image_url":null,"twitter_image_custom_url":null,"twitter_image_custom_fields":null,"twitter_title":null,"twitter_description":null,"schema":{"blockGraphs":[],"customGraphs":[],"default":{"data":{"Article":[],"Course":[],"Dataset":[],"FAQPage":[],"Movie":[],"Person":[],"Product":[],"ProductReview":[],"Car":[],"Recipe":[],"Service":[],"SoftwareApplication":[],"WebPage":[]},"graphName":"","isEnabled":true},"graphs":[]},"schema_type":null,"schema_type_options":null,"pillar_content":false,"robots_default":true,"robots_noindex":false,"robots_noarchive":false,"robots_nosnippet":false,"robots_nofollow":false,"robots_noimageindex":false,"robots_noodp":false,"robots_notranslate":false,"robots_max_snippet":null,"robots_max_videopreview":null,"robots_max_imagepreview":"large","priority":null,"frequency":null,"local_seo":null,"seo_analyzer_scan_date":null,"breadcrumb_settings":null,"limit_modified_date":false,"reviewed_by":null,"ai":null,"created":"2021-02-28 19:46:29","updated":"2022-10-01 02:03:35","focus_keyword":null,"additional_keywords":null,"truseo_locale":null},"gt_translate_keys":[{"key":"link","format":"url"}],"_links":{"self":[{"href":"https:\/\/prohoster.info\/da\/wp-json\/wp\/v2\/posts\/55281","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/prohoster.info\/da\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/prohoster.info\/da\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/prohoster.info\/da\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/prohoster.info\/da\/wp-json\/wp\/v2\/comments?post=55281"}],"version-history":[{"count":0,"href":"https:\/\/prohoster.info\/da\/wp-json\/wp\/v2\/posts\/55281\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/prohoster.info\/da\/wp-json\/wp\/v2\/media\/55282"}],"wp:attachment":[{"href":"https:\/\/prohoster.info\/da\/wp-json\/wp\/v2\/media?parent=55281"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/prohoster.info\/da\/wp-json\/wp\/v2\/categories?post=55281"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/prohoster.info\/da\/wp-json\/wp\/v2\/tags?post=55281"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}