Racket version 5.1.1 is now available from http://racket-lang.org/
* The new `racket/stream' library provides `stream-first', `stream-rest', a lazy `stream-cons', and so on. Streams are a subtype of sequences, so they work in `for' forms. Some sequence generators, such as `in-range', now produce streams. A `racket/sequence' library replaces the old `racket/stream' library. * The new `racket/syntax' library contains facilities useful for writing macros. The new `syntax/srcloc' and `syntax/location' libraries provide support for manipulating source locations. * The `racket/gui' library now supports multi-column list boxes and scrolling panels. * The new `ffi/file' library is useful for writing foreign library bindings that cooperate with Racket's security guard mechanism. * Generators from the `racket/generator' library can now have formal arguments that are used when the generator is fired up. * Single-precision floating-point support is now enabled by default. Single-precision floats print differently from their default double-precision counterparts, new primitives convert between the two precisions, and new reader syntax supports single-precision literals. * JIT improvements include a small change to aid x86 branch prediction on function-call returns, which can speed up some programs significantly. * Typed Racket: - The numeric tower has been entirely overhauled. TR programs can now use more precise types than before, and check more numeric properties, such as sign or range properties. - Fixnum optimizations have been improved and should apply more broadly. - The performance of the typechecker has been improved. In particular, dispatch on large union types should typecheck much faster than before. * The Stepper can now step through Lazy Racket programs. * The `racket/future' library includes `fsemaphore' values, the `future' primitive no longer freezes futures (so a future can spawn new futures), and `future' log messages are more informative. * PLaneT development links are now version-specific. * The `2htdp/image' library now includes `overlay/align', `underlay/align', `overlay/align/offset' and `underlay/align/offset'. * The network protocol for universes in `2htdp/universe' has changed, so that v5.1.1 is incompatible with earlier versions. * The "DrScheme" application (which simply ran DrRacket in the last few releases) has been removed. The "MrEd" GUI executables for Windows and Mac OS X have also been removed, although the "mred" console executable remains for Unix and Mac OS X to support old scripts. [Note that mirror sites can take a while to catch up with the new downloads.] Feedback Welcome, -- ((lambda (x) (x x)) (lambda (x) (x x))) Eli Barzilay: http://barzilay.org/ Maze is Life! ______________________________________________________ Racket Announcements list announce@racket-lang.org http://lists.racket-lang.org/listinfo/announce