Racket

It supports the creation of new programming languages through a rich, expressive syntax system.

Racket, as its predecessor PLT Scheme is a variant of Scheme.

The language supports scripting.

What is new in this release:

• The package manager supports a direct references to Git repositories.
• A `--clone` option for `raco pkg install` or `raco pkg update` facilitates Git-based package development.

What is new in version 6.2.1:

• The package manager supports a direct references to Git repositories.
• A `--clone` option for `raco pkg install` or `raco pkg update` facilitates Git-based package development.

What is new in version 6.2:

• The package manager supports a direct references to Git repositories.
• A `--clone` option for `raco pkg install` or `raco pkg update` facilitates Git-based package development.

What is new in version 6.1.1:

• Racket's HTML documentation has a new and improved look.
• The documentation includes a style guide.
• Racket's JIT compiler supports the ARM architecture.
• Racket supports the Mac's Retina display mode.
• The performance of the Typed Racket compiler improved by 50% on some typed programs.
• The profiler provides a new mode that uses the errortrace library to produce fine-grained profiles.
• A new contract profiler reports how much time programs spend checking contracts, and which contracts are most expensive.
• The math/flonum library exports fast 105-bit precision operations.

What is new in version 5.3.4:

• Tally Maze: a new game based an enumeration of 2D mazes.
• The Optimization Coach, a DrRacket plugin, has been moved from the Racket distribution to the Racket package repository. Install it with: raco pkg install optimization-coach.
• Redex: `define-union-language' now merges productions when languages define the same nonterminals.
• The `srfi/19' library is now compatible with the date structure type exported by `racket/base'.

What is new in version 5.3.2:

• The new `file/untar', `file/untgz', and `file/unzip' libraries support unpacking widely used archive formats.
• The new `lazy-require' form allows programs to delay the loading and instantiation of helper modules until they are needed.
• The new `data/bit-vector' library provides an implementation of bit vectors (a mutable sequence of booleans) supporting popcount.
• The `racket/generic' library allows the specification of default method implementations for core datatypes.
• The `openssl' library can verify hostnames and use the operating system's certificate store to verify certificates.

What is new in version 5.2.1:

• DrRacket uses a set of composable ray-traced icons available from the new `images' library collection.
• Typed Racket's `typecheck-fail' form allows macro creators to customize the error messages that Typed Racket produces. This is especially useful when creating pattern matching macros.
• The performance of Redex's matcher has been substantially improved; depending on the model you should see improvements between 2x and 50x in the time it takes to reduce terms.
• Plots look nicer and are more correct at very small and very large scales. New features include customizable dual axis ticks and transforms (e.g., log axes, date and currency ticks, axis interval collapse and stretch), stacked histograms, and 3D vector fields. The legacy `fit' function and libfit have been removed.
• The `2htdp/universe' library's `big-bang' form supports an experimental game pad key handler.
• The `db' library now supports nested transactions and PostgreSQL arrays. Bugs involving MySQL authentication and memory corruption in the SQLite bindings have been fixed.