Poly/ML is a Standard ML implementation originally written in an experimental language called Poly. It has been fully compatible with the ML97 standard since version 4.0. For a full history, see here.

Poly/ML takes a conservative approach to the Standard ML language and avoids incompatible extensions. It has added various library extensions particularly the thread library. Poly/ML's active development and unique features make it an exceptional implementation.

• Fast compiler
• Preferred implementation for large projects such as Isabelle and HOL.
• Foreign function interface - allows static and dynamic libraries to be loaded in Poly/ML and exposes their functions as Poly/ML functions. See here for an example of static linking.
• Symbolic debugger
• Windows programming interface
• Thread library - provides a simplified version of Posix threads modified for Standard ML and allows Poly/ML programs to make use of multiple cores. The garbage collector is also parallelised.

The documentation for the Poly/ML Basis library can be found here and includes information on global values and types as well as structures, signatures and functors. More in-depth documentation can be found at the SML Family website here.

Poly/ML has native support for i386 (32- and 64-bit) and ARM (64-bit only). It will also work on other architectures using a byte-code interpreter. For more information, see the download page.

There is a mailing list for Poly/ML for questions and support.