Context: Trait composition has inspired new research in the area of code reuse for object oriented (OO) languages. One of the main advantages of this kind of composition is that it makes possible to separate subtyping from subclassing; which is good for code-reuse, design and reasoning. However, handling of state within traits is difficult, verbose or inelegant.
Inquiry: We identify the this-leaking problem as the fundamental limitation that prevents the separation of subtyping from subclassing in conventional OO languages. We explain that the concept of trait composition addresses this problem, by distinguishing code designed for use (as a type) from code designed for reuse (i.e. inherited). We are aware of at least 3 concrete independently designed research languages following this methodology: TraitRecordJ, Package Templates and DeepFJig.
Approach: In this paper, we design 42µ, a new language, where we improve use and reuse and support the This type and family polymorphism by distinguishing code designed for use from code designed for reuse. In this way 42µ synthesise the 3 approaches above, and improves them with abstract state operations: a new elegant way to handle state composition in trait based languages.
Knowledge and Grounding: Using case studies, we show that 42µ’s model of traits with abstract state operations is more usable and compact than prior work. We formalise our work and prove that type errors cannot arise from composing well typed code.
Importance: This work is the logical core of the programming language 42. This shows that the ideas presented in this paper can be applicable to a full general purpose language. This form of composition is very flexible and could be used in many new languages.
Wed 3 AprDisplayed time zone: Amsterdam, Berlin, Bern, Rome, Stockholm, Vienna change
11:00 - 12:30
|Separating Use and Reuse to Improve Both|
Hrshikesh Arora , Marco Servetto Victoria University Wellington, New Zealand, Bruno C. d. S. Oliveira The University of Hong Kong, Hong KongLink to publication DOI Pre-print
|Clafer: Lightweight Modeling of Structure, Behaviour, and Variability|
Paulius Juodisius IT University of Copenhagen, Denmark, Atrisha Sarkar University of Waterloo, Canada, Raghava Rao Mukkamala Department of Technology, Kristiania University College, Norway, Michal Antkiewicz University of Waterloo, Canada, Krzysztof Czarnecki University of Waterloo, Canada, Andrzej Wąsowski IT University of Copenhagen, DenmarkLink to publication DOI Pre-print
|Shallow EDSLs and Object-Oriented Programming: Beyond Simple Compositionality|
Weixin Zhang The University of Hong Kong, Hong Kong, Bruno C. d. S. Oliveira The University of Hong Kong, Hong KongLink to publication DOI Pre-print