Refined Criteria for Gradual Typing

Putting gradual types to work

“…Since its introduction, gradual typing [23] has been making its way into more mainstream languages [30,29] and more people have acknowledged the varied benefits of mixing static and dynamic typing in the same program. As identified by Siek and Taha [26], there has been considerable interest in integrating static and dynamic typing, both in academia and in industry. There has also been a plethora of proposed approaches, from adding a dynamic keyword [2], to using objects in object-oriented languages [16], to Seik and Taha's gradual typing itself [23].…”

“…There has also been a plethora of proposed approaches, from adding a dynamic keyword [2], to using objects in object-oriented languages [16], to Seik and Taha's gradual typing itself [23]. While there seems to be no one-sizefits-all approach to designing a system that mixes static and dynamic types, Siek and Taha standardize the guarantees [26] we can expect from such a system. For language designers, this provides a more methodical way to approach the integration.…”

“…Note that throughout this paper we use "gradual" to indicate an implementation that provides gradual guarantees as specified in [26]. While, we do not state this formally for BCL and leave that to future work, our implementation supports the smooth evolution of programs from static to dynamic typing as prescribed for gradually typed systems.…”

“…In this section we briefly survey the existing literature to better contextualize our design choices. The incorporation of static and dynamic typing has been extensively studied [28,15,23,26,8], though usually in the context of a core calculus instead of a full-featured language. There also seems to be a juxtaposition of the literature, which generally follows a static-first approach, and practical implementations, which generally follow a dynamic-first approach 3 [7].…”

“…Unification-based inference is a common implementation of the Hindley-Milner type system [17], and is the implementation that BCL already uses. This makes our integration work relatively easier and also lets us leverage all the benefits of the standard for gradual typing laid out by Siek and Taha [26]. Siek and Vachchrajani [25](S&V) propose an innovative solution for performing gradual type inference which combines gradual typing with type inference.…”