The general goal of our research group is to design and implement programming languages based on solid theoretical foundations. Actually, however, not so many values are judged to be linear by traditional linear type systems, hence their applications have been rather limited. In order to overcome this limitation, we developed a new variant of linear type system, called a quasi-linear type system.
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The main difficulty was that the region-based memory management may create dangling pointers. On this topic, only a paper written in Japanese is available right now. Based on Linear Logic Basic computation models are important for good design and implementation of programming languages. A concurrent programming language HACL was designed and implemented based on the framework. It can be considered an ML extended with primitives for parallel execution, dynamic creation of first-class communication channels, and asynchronous communication over those channels.