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ATS2 - ATS/Postiats

A Programming Language System to Unleash the Potentials of Types and Templates

Project Description

ATS/Postiats (or ATS2/Postiats) is the name for the current compiler of ATS2, the successor of ATS (or ATS1).

The actual implementation of ATS/Postiats started in the March of 2011, and it took about two and one-half years to reach the first release of ATS2 at the beginning of September, 2013. As of now, the code base for the compiler of ATS2 consists of 180,000+ lines of code (LOC), which are nearly all written in ATS1.

When compared to ATS1, the single most important new feature is the template system of ATS2. This is a feature that could potentially change the way a programmer writes his or her code. One can certainly feel that this is a very powerful feature (a bit like feeling that OOP is a very powerful feature). However, how this feature should be properly and effectively used in practice needs a lot more investigation.

Another thing about ATS2 is that it is a lot leaner than ATS. One can make good use of ATS2 without any need for compiled library (libatslib.a). Also, GC support in ATS1 is now removed; if needed, third-party GC (e.g., Bohem-GC) can be readily employed.

Build Status

  • Build Status Ubuntu
  • Build Status Cygwin

Installing ATS2

Please see for instructions.

Note that the code in this github directory is primarily meant for people who would like to help develop ATS2. For someone who just wants to program in ATS2, please install the current release of ATS2, which can be found at the following site: There are also pre-compiled debian packages for ATS2 available on-line.

Developing ATS2

The compiler of ATS2 is nearly all implemented in ATS1, which is available at

Documenting ATS2

ATS-users are encouraged to share what they have learned on the ATS2 wiki, which currently contains over 45 articles with content. A list of article stubs is maintained at TODO.

Licenses for ATS/Postiats

  • The Compiler (ATS/Postiats): GPLv3
  • The ATS source for the Libraries (ATSLIB/{prelude,libats}): LGPLv3.
  • As a special exception, any C code generated by the Compiler based on the Libraries source is not considered by default to be licensed under GPLv3/LGPLv3. If you use such C code together with other code to create an executable, then the C code by itself does not cause the executable to be covered by GPLv3/LGPLv3. However, there may be reasons unrelated to using ATS that can result in the executable being covered by GPLv3/LGPLv3.
  • The contributed portion (ATS/Postiats/contrib) is released under the MIT license.
  • There is also a release under the MIT license for the C header files of the Libraries, which one can, for instance, freely insert into C code generated from ATS source code.
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