Racket 6.2.1

Version 6.2.1 patches the recent v6.2 release in three small ways:

* For the How to Design Programs teaching languages, DrRacket offers
  an option to use the old style for printing the constants `true`,
  `false`, and `empty` instead of `#true`, `#false`, and `'()`.

* The teaching languages come with some additional functions to match
  the August 2015 stable release of HtDP 2nd edition.

* A repair to the compiler avoids an infinite loop at compile time for
  certain expressions that should loop forever at run time.

Merge git.racket-lang.org:plt

Racket v6.2

With this release we are taking a major step forward to get our user
community even more involved than in the past. Over the past six months,
we have re-organized the Racket code base into a small core code repo
and many other package repos, all found on github. If you have time and
if you wish to get involved, please take a look at the github repos and
find your favorite places to learn, fix, and enhance our world.

The core repo is at https://github.com/plt/racket, and the
package repos are listed at https://github.com/racket/.

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`.

Racket v6.1.1

* The MAC OS X YOSEMITE compatibility problems are fixed. We
  bundled a patched Pango text-drawing library with Racket.

* The WINDOWS [32-bit] releases fixes the window-update crashes.
  We bundled a patched Cairo drawing library with Racket.

* TYPED RACKET closes two safety holes in the exception system.
  The revised type system restricts `raise' to send only
  instances of the `exn' structure type and flat data to
  handlers. It also checks exception handlers properly.
  NOTE: Previously well-typed programs may fail to typecheck.

* TYPED RACKET'S typed regions support casts and predicates.

* 2HTDP/IMAGE'S notion of equality ignores an image's baseline.

* The PACKAGE MANAGER supports a binary library installation mode,
  which allows users to install packages without source or documentation.
  Use the `--binary-lib' option with `raco pkg install'.

* The new DRRACKET-TOOL-LIB package factors out parts of DrRacket's
  IDE so that they can be reused with other editors, such as Emacs.

* The COMPILER'S use-before-defined analysis has been repaired for
  certain forms of nested `letrec', some `let' forms, and some
  uses of `set!' or `with-continuation-mark'.

* The COMPILER performs additional bytecode optimizations.
  Thanks to Gustavo Massaccesi.

* The CML library comes with a new `replace-evt' event constructor.
  Thanks to Jan Dvořák.

* REDEX'S benchmark suite comes with a description of the benchmark
  programs.

* REDEX'S metafunctions can be typeset using the "large left brace"
  notation for conditionals.

* The CONTRACT library comes with an improved `contract-stronger?'.
  Its error messages note that the contract itself might be wrong.

* The GUI library is DPI-aware on Windows.

* The OPENSSL library supports Server Name Indication for servers.
  Thanks to Jay Kominek.

* The SYNTAX/PARSE library allows the definition of new pattern
  forms via pattern expanders, similar to match expanders.
  Thanks to Alex Knauth.

* OpenGL on Linux no longer depends on libgtkgl, and core profiles
  are supported (see `set-legacy?').

* The TEACHING LANGUAGES' unit test framework supports
  `check-satisfied', a construct for checking whether a result
  satisfies a predicate, e.g.: (check-satisfied (sort l) sorted?)