First-class citizen
In programming language design, a first-class citizen (also type, object, entity, or value) in a given programming language is an entity which supports all the operations generally available to other entities. These operations typically include being passed as an argument, returned from a function, modified, and assigned to a variable.[1]
The simplest scalar data types, such as integer and floating-point numbers, are nearly always first-class.
In many older languages, arrays and strings are not first-class: they cannot be assigned as objects or passed as parameters to a subroutine. For example, neither Fortran IV nor C supports array assignment, and when they are passed as parameters, only the position of their first element is actually passed—their size is lost. C appears to support assignment of array pointers, but in fact these are simply pointers to the array's first element, and again do not carry the array's size.
In most languages, data types are not first-class objects, though in some object-oriented languages, classes are first-class objects and used for metaclasses.
Few languages support continuations and GOTO-labels as objects at all, let alone as first-class objects.
Concept | Description | Languages |
---|---|---|
first-class function | closures and anonymous functions | Scheme, ML, Haskell, F#, Scala, Swift, PHP, Perl 6, JavaScript |
first-class control | continuations | Scheme, ML, F# |
first-class type | Coq, Idris | |
first-class data type | Generic Haskell. C++11 | |
first-class polymorphism | impredicative polymorphism | |
first-class message | dynamic messages (method calls) | Smalltalk,[7] Objective-C[7] |
first-class class | metaclass | Smalltalk, Objective-C, Ruby, Python |
proof object[8] | Coq, Agda |
First-class citizen的更多相关文章
- WordPress Citizen Space插件跨站请求伪造漏洞
漏洞名称: WordPress Citizen Space插件跨站请求伪造漏洞 CNNVD编号: CNNVD-201307-463 发布时间: 2013-07-23 更新时间: 2013-07-23 ...
- 什么是First-class citizen?
[什么是First-class citizen?] In programming language design, a first-class citizen (also type, object, ...
- 【NLP】Python NLTK获取文本语料和词汇资源
Python NLTK 获取文本语料和词汇资源 作者:白宁超 2016年11月7日13:15:24 摘要:NLTK是由宾夕法尼亚大学计算机和信息科学使用python语言实现的一种自然语言工具包,其收集 ...
- 用Kotlin语言重新编写Plaid APP:经验教训(II)
原文标题:Converting Plaid to Kotlin: Lessons learned (Part 2) 原文链接:http://antonioleiva.com/plaid-kotlin- ...
- 【Codeforces163E】e-Government AC自动机fail树 + DFS序 + 树状数组
E. e-Government time limit per test:1 second memory limit per test:256 megabytes input:standard inpu ...
- windows安装rabbitmq
官网下载windows安装版本:http://www.rabbitmq.com/install-windows.html ,安装文件rabbitmq-server-3.6.5.exe 前提:安装erl ...
- 树莓派pppoe
连接的网络是移动(铁通)的宽带,不同的宽带的dns需要修改. 1.首先安装pppoe包 apt-get install pppoe 2.然后,复制conf文件/etc/ppp/pppoe.conf: ...
- Lesson 1 A private conversation
Text Last week I went to the theatre. I had a very good seat. The play was very intersting. I did no ...
- Functional Programming without Lambda - Part 1 Functional Composition
Functions in Java Prior to the introduction of Lambda Expressions feature in version 8, Java had lon ...
随机推荐
- php配置站点
第一步:需要打开三个文件 1.C:\wamp\bin\apache\apache2.4.9\conf\httpd.conf 2.C:\wamp\bin\apache\apache2.4.9\conf\ ...
- usaco 最少找零
Description 约翰在镇上买了 T 元钱的东西,正在研究如何付钱.假设有 N 种钞票,第 i 种钞票的面值为 Vi,约翰身上带着这样的钞票 Ci 张.商店老板罗伯是个土豪,所有种类的钞票都有无 ...
- 微信小程序引用阿里巴巴矢量图标iconfont
最近在写微信小程序,但是引用图片,导致项目文件太大,所以就想到引用阿里巴巴矢量图标的方法 第一步:下载阿里巴巴矢量图代码: 第二步:将下载下来的文件中iconfont.ttf转换即可.转换地址:htt ...
- javascript中缓存
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8&quo ...
- mock non-virtual methods
生产代码中有很多类方法是非虚的,而为了在Gtest中解除这些非必需的依赖,可以通过Gmock的mock non-virtual methods using templates方法来达到目的.在此之前, ...
- Prototype-based programming
Prototype-based programming is a style of object-oriented programming in which behaviour reuse (know ...
- Spark机器学习之MLlib整理分析
友情提示: 本文档根据林大贵的<Python+Spark 2.0 + Hadoop机器学习与大数据实战>整理得到,代码均为书中提供的源码(python 2.X版本). 本文的可以利用pan ...
- 异常值(outlier)
简介 在数据挖掘的过程中,我们可能会经常遇到一些偏离于预测趋势之外的数据,通常我们称之为异常值. 通常将这样的一些数据的出现归为误差.有很多情况会出现误差,具体的情况需要就对待: 传感器故障 -> ...
- 树形dp复习 树上依赖背包问题
选课 今天又看了一下这道题,竟然AC不了了 自己的学习效率有点低下 要明白本质,搞透彻 #include<bits/stdc++.h> #define REP(i, a, b) for(r ...
- invalid application of `sizeof' to incomplete type `char[] '
在写代码时,我想用extern来关联一个数组,然后利用sizeof计算数组的大小,代码如下: ... extern char a[]; #define b size=(sizeof(a)/sizeof ...