编程与软件工程archive.vector.org.uk
K 编程语言（2005）
K programming language (2005)
2014 — 2020，它一次次回到首页
黑点是上首页（≥ 50 分）的那次投稿，空心点是没冲上去的投稿，点越大分数越高。
导读
这篇 2005 年的 Vector 杂志文章介绍 K 编程语言（据评论主要讲 K2），用简洁示例展示这种极简数组语言的核心构造与思路。K 后来演进出 K4/K6，并影响了商业化的 kdb+/Q，在高性能金融数据处理中影响深远。
为什么经久不衰：它用很短篇幅呈现 APL 家族“少而密”的编程范式，是理解 K/Kdb+ 和数组语言设计哲学的经典入口，今天仍值得读。
HN 评论精选
文章虽老仍是 K2 的好入门；后续 K4/K6 已大幅演进，并推荐 ok 和《Q for Mortals》作为上手资源。
这篇简洁的文章描述的是 K2（K 语言的第 2 版）；就它覆盖的层面而言，之后几乎没变，所以 12 年后它仍是很好的 K 入门。但基础之外变化很大（当前商业版是 K4，当前开发版据我所知是 K6）：字典更好地融入语言，数据库层被并入语言，原先集成的极简 GUI 被移除，HTTP/Web（客户端和服务端）加入核心，64 位整数、纳秒时间戳、GUID 成为核心类型，可能还有些我忘了。若觉得有趣，可玩 JohnEarnest 的 ok（JS 实现、到处能跑的图形游乐场），并读《Q for Mortals》——Q 是 K4 的语法糖版本，底层仍是同一门语言。
beagle3查看英文原文
This concise article describes K2 (version 2 of the K language), and, at the level it describes, little has changed, so it is still a good introduction to the language 12 years later. However, beyond the basics, a lot has changed since (current commercial version is K4, current dev is K6 AFAIK): Dictionaries have become better integrated in the language, the database layer was rolled into the language, the integrated (bare bones and milspec-looking but ultra effective) electric GUI was dropped, http and web (as both client and server) were added to the core, 64-bit integers, nanosecond timestamps, GUIDs were added as core types, and probably a few more things I forgot. If you find this article interesting, you may want to experiment with JohnEarnest's ok [0], which provides graphical playground (implemented in JS and runs everywhere) and also read Q for mortals[1] - Q is a syntactic-sugar version of K4, though still the same language underneath. [0] https://github.com/JohnEarnest/ok [1] http://code.kx.com/q4m3/
给出两条试用路径：Kx 的 32 位 kdb+（K4）和开源 Kona（K3）。
想试 K，可以从 Kx 下载 32 位 kdb+；在提示符输入单独的 \ 会进入 K 模式，用的是 K4。另一个选择是免费开源的 Kona，它实现的是上一代 K3。
icen查看英文原文
If you want to try out K, you can either go to Kx and download the 32bit version of kdb+. \ at the prompt (on its own) will enter K mode. This uses K4. Alternatively, there's the free and open source Kona, which is an implementation of K3, the preceding version. https://kx.com/download https://github.com/kevinlawler/kona
实际使用体验：符号门槛后代码极密集、环境小巧且启发性强，主要痛点是互操作。
我大学时不得不写很多 K（这暴露了我的学校，也会让写过 K 的人困惑：你居然能写很多 K）。越过符号带来的困惑后，它其实很有启发性。我能体会用真正符号的 APL 会有多高效。你的代码会变得超级密集，非平凡的东西几屏就能放下，便于把握全局（用 K 构建的商业列式数据库 KDB 以功能多而体积小得惊人著称）。我记得真正的痛点是和其他系统对接，但整个环境非常小。它拓展了我的思维，让我希望世界有朝一日重新审视 APL 家族的思想。
fidotron查看英文原文
I had to write a lot of K at university (thus disclosing where I went to, and confusing people that have written any K with the idea you could possibly write a lot of it). Get by the symbolic confusion (Arthur himself used to respond to confused students on the mailing list about such things) and it's really quite inspired. I can appreciate how an APL with proper symbols would be properly productive. Your code ends up super dense, with non-trivial stuff easily fitting on just a few screens, so you can keep track of what's going on. (KDB itself, the commercial column based DB product built with K, was notoriously small for the functionality). The real pain I seem to recall was interfacing it with anything else, but the entire environment is tiny. This is one of those languages that really expanded my mind and made me hope the rest of the world would one day revisit the ideas of the APL family.
Q/kdb+ 在金融高性能场景久经考验，且 32 位试用包小得惊人（278KB）。
K 的后继 Q 在金融系统中大量使用，而且贵得离谱。尽管如今大数据很热，我认为 Q 早已在处理极大规模数据，性能惊人。kdb+ 的 32 位试用版可用于非商业用途，我下载了；Linux zip 只有 278KB。好吧！我本以为还会下更多东西（像 Chrome 安装那样），但没有，就这些。
karterk查看英文原文
K's successor Q is used heavily in financial systems and costs a bomb. Despite all the big data rage these days, I think Q has been handling very high volumes of data for a while now with some amazing performance. The 32-bit trial version of kdb+ is available for non-commercial use [1], so I went and downloaded it. The linux zip download is 278KB. Uh ok! I was expecting it to download more stuff (much like Chrome's installation), but nope, that's all there is to it! [1]: http://kx.com/software-download.php
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