Typing the Wild in Erlang
Paper i proceeding, 2018

Developing a static type system suitable for Erlang has been of ongoing interest for almost two decades now. The challenge with retrofitting a static type system onto a dynamically typed language, such as Erlang, is the loss of flexibility in programming offered by the language. In light of this, many attempts to type Erlang trade sound type checking for the ability to retain flexibility. Hence, simple type errors which would be caught by the type checker of a statically typed language are easily missed in these developments. This has us wishing for a way to avoid such errors in Erlang programs. In this paper, we develop a static type system for Erlang which strives to remain sound without being too restrictive. Our type system is based on Hindley-Milner type inference, however it - -unlike contemporary implementations of Hindley-Milner - -is flexible enough to allow overloading of data constructors, branches of different types etc. Further, to allow Erlang's dynamic type behaviour, we employ a program specialization technique called partial evaluation. Partial evaluation simplifies programs prior to type checking, and hence enables the type system to type such behaviour under certain restricted circumstances.


Partial Evaluation

Type Inference


Nachiappan Valliappan

Chalmers, Data- och informationsteknik, Informationssäkerhet

John Hughes

Chalmers, Data- och informationsteknik, Funktionell programmering

Erlang 2018 - Proceedings of the 17th ACM SIGPLAN International Workshop on Erlang, co-located with ICFP 2018

978-145035824-8 (ISBN)

17th ACM SIGPLAN International Workshop on Erlang, Erlang 2018, co-located with the Annual International Conference on Functional Programming, ICFP 2018
St. Louis, USA,


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