Free 4.3.0 software for mac

Gambit-C 4.1.2 is such a great program including a Scheme interpreter and a Scheme compiler which can be used to build standalone executables. Because the compiler generates portable C code it is fairly easy to port to any platform with a decent C compiler. The thread system is very efficient and can support millions of concurrent processes.

The Gambit-C system conforms to the R4RS, R5RS and IEEE Scheme standards. The full numeric tower is implemented, including: infinite precision integers (bignums), rationals, inexact reals (floating point numbers), and complex numbers.

Major Features:

1. Conformance. The Gambit-C system conforms to the R4RS, R5RS and IEEE Scheme standards and implements all optional features. Tail calls and first class continuations conform to the Scheme semantics. The full numeric tower is implemented, including: arbitrary precision integers (bignums), rationals, inexact reals (floating point numbers), and complex numbers. Several extensions to Scheme are provided, including: lightweight threads, a foreign-function interface (FFI), and extended I/O capabilities (Unicode, networking, subprocesses, ...).
2. Portability. Because the system is mostly written in Scheme and the compiler generates portable C code, it is easy to port the system as well as programs compiled with it to any platform with a decent C or C++ compiler. There is no reliance on a particular C compiler, although the system can take advantage of some gcc-specific constructs. The C code generated is oblivious to the endianness and word size of the target environment (32 and 64 bit architectures are currently supported).
3. Performance. The compiler includes several powerful program transformations such as user procedure inlining, partial-evaluation, and lambda-lifting. With appropriate declarations in the source code the executable programs generated by the compiler run roughly as fast as equivalent C programs. Programs containing no declarations are also optimized without compromising the Scheme semantics by speculatively inlining predefined procedures. Thanks to an efficient implementation of continuations, the thread system is very efficient and can support millions of concurrent threads. The bignum library uses sophisticated algorithms that are in some cases asymptotically faster than those of GMP (GNU Multiple Precision Arithmetic Library). [Note: With the release of GMP 4.3.0 in April 2009, this claim is no longer true; ]
   
4. Reliability. Stable releases typically have very few bugs. Bug tracking is done with bugzilla. Gambit-C has been used to develop large-scale real-world software in academic and commercial settings.

• Mac OS X 10.3 or later.

ATutor 1.6.3b1 is a rather praiseworthy Open Source Web-based Learning Content Management System (LCMS) which has accessibility and adaptability in mind.

Administrators can install or update ATutor in minutes, and develop custom templates to give ATutor a new look. Educators can quickly assemble, package, and redistribute Web-based instructional content, easily retrieve and import prepackaged content, and conduct their courses online. Students learn in an adaptive learning environment.

ATutor is the first fully inclusive LCMS, complying with the W3C WCAG 1.0 accessibility specifications at the AA+ level, allowing access to all potential learners, instructors, and administrators, including those with disabilities who may be accessing the system using assistive technologies. Conformance with W3C XHTML 1.0 specifications ensures that ATutor is presented consistently in any standards compliant technology.