发布于 2015-06-21 00:17:07 | 243 次阅读 | 评论: 0 | 来源: 网友投递
Racket 编程语言
Racket，既PLT Scheme，是一种可编程的计算机程序设计语言 ，同时也是一个程序设计环境。是Scheme众多实现中的一种。
Racket 6.2 发布了，在这个版本中我们对核心库进行了优化和减缩，并将代码迁移到 Github 上。
目前核心库的源码请看 https://github.com/plt/racket, 和扩展包的源码 https://github.com/racket/.
Racket源自著名的专家型语言PLT Scheme，同时又是Lisp语言的一个分支。它适用于从脚本Script到应用程序开发的任务执行工具，包括图形用户界面，Web服务器等。支持编译器的虚拟机，创建独立的可执行程序的工具，Racket Web服务器，具有丰富而全面的功能库，适用于初学者和专家编程。
Racket，既PLT Scheme，是一种可编程的计算机程序设计语言 ，同时也是一个程序设计环境。是Scheme众多实现中的一种。
其他改进内容包括：
core repo
* The package manager supports a direct references to Git repositories
via "git://[...]", "http://[...].git", and "https://[...].git" URLs.
(Previously, only references to GitHub were supported.)
* A `--clone` option for `raco pkg install` or `raco pkg update`
facilitates Git-based package development. If a package X has a Git
repository source, installing and updating the package pulls from the
repository in a read-only mode. Using `raco pkg update --clone X`
switches the local installation to a repository checkout that is
suitable for modifying the package implementation, issuing pull
requests, pushing changes, and so on.
Using `raco pkg update --lookup X` switches the package back to the
default installation mode.
drracket
* Its on-line check syntax works with graphical content.
* Increased availability of DrRacket's blueboxes, including method and
constructor information.
* The "Open Require Path" menu item supports ".." in relative pathnames.
data
* Added data/enumerate, a library that supports efficient enumeration of
data structures
redex
* Its redex-check facility uses data (in addition to random) enumeration
to try to find counter-examples.
* Its generate-term function accepts additional arguments to return the
"i"-th member of a pattern using data/enumerate (meaning it
efficiently supports very large values of "i").
* The examples collection includes Launchbury's 1993 big-step lazy
semantics.
htdp
* 2htdp/image's polygon may be built out of bezier curves instead of
just straight lines (see the docs for "pulled-point").
* 2htdp/abstraction is a teachpack for instructors and students who wish
to use for/* loops, match, define-type and type-cases in ISL and ISL+.
* 2htdp/universe programs can be exported using DrRacket's executable
creation mechanism and they behave properly when run independently.
typed-racket
* Typed Racket in DrRacket displays tooltips that show the types of
expressions. Tooltips are also displayed for type errors.
* Typed Racket loads generated contracts only when needed. This reduces
memory use and startup time for Typed Racket programs.
* Typed Racket has improved support for prefab structures, future
semaphores, and async channels.
* Typed Racket understands when two different variables refer to the
same thing, and updates types accordingly. This particularly improves
the type checking of macros such as `match`