Haskell session types with (almost) no class

Pucella, Riccardo; Tov, Jesse A.

doi:10.1145/1411286.1411290

Cited by 66 publications

(89 citation statements)

References 24 publications

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“…The protocol combinators are highly inspired from Pucella and Tov's encoding of duality [25]. To the author's knowledge, the addition of delegation and recursion to [25] is new. We believe the simplification of recursion adds more readability to programs using protocol-combinator based implementations.…”

Section: Discussionmentioning

confidence: 99%

“…The main difference from the one by Pucella and Tov [25] is that, to avoid notational overhead, we stick on flat tuple-based representation (S0,S1,..) rather than a nested cons-based list Cons<S0,Cons<S1,..>>. This also elides manual unfolding of a recursive type from µα.T to T [µα.T /α] encoded as enter in [25], resulting in a less notational overhead in recursive session types than [25]. This ad-hoc encoding comes at a cost; the number of cycles in a recursive session is limited because the size of the tuple is limited, we must overload methods since we do not have a structural way to manipulate tuple types -although the maximum size of tuples of 8-9 seems enough for a tractable communication program.…”

Section: Recursive Sessions Flatlymentioning

confidence: 99%

“…Figure 8 is a client to Bitcoin miner shown in § 3. Figure 10 is an implementation of parallel polygon clipping from [25], where Pipeline creates a series of threads connected by two session-typed channels of which session type is described in a protocol specification.…”

Section: B More On Recursion and Delegationmentioning

confidence: 99%

“…Also, there is a small hack: The use of Func in the payload of Send and Recv enables omitting the parenthesis () after Val<V> in protocol specifications (as in prot in § 1). Figure 10: Polygon Clipping Pipeline [25]…”

Section: A Protocol Combinatorsmentioning

confidence: 99%

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Fluent Session Programming in C#

Kimura

Imai

2020

Electron. Proc. Theor. Comput. Sci.

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We propose SessionC#, a lightweight session typed library for safe concurrent/distributed programming. The key features are (1) the improved fluent interface which enables writing communication in chained method calls, by exploiting C#'s out variables, and (2) amalgamation of session delegation with async/await, which materialises session cancellation in a limited form, which we call session intervention. We show the effectiveness of our proposal via a Bitcoin miner application. IntroductionSession types [8] are a theoretical framework for statically specifying and verifying communication protocols in concurrent and distributed programs. Session types guarantee that a well-typed program follows a safe communication protocol free from reception errors (unexpected messages) and deadlocks.The major gaps between session types and "mainstream" programming language type system are the absence of the two key features: (1) duality for checking the communication protocol realises reciprocal communication actions between two peers, and (2) linearity ensuring that each peer is exactly following the protocol, in the way that channel variables are exclusively used from one site for the exact number of times. Various challenges have been made for incorporating them into general-purpose languages including Java [12], Scala [28], Haskell [25,14,19,23], OCaml [24,13] and Rust [15,16].We observe that the above-mentioned gaps in session-based programming can be narrowed further by the recent advancement of programming languages, which is driven by various real-world programming issues. In particular, C# [1] is widely used in areas ranging from Windows and web application platforms to gaming (e.g. Unity), and known to be eagerly adopting various language features including async/await, reifiable generics, named parameters, out variables and extension methods.In this paper, we propose SessionC# -a library implementation of session types on top of the rich set of features in C#, and show its usefulness in concurrent/distributed programming, aiming for practicality. client server (int,int,int) «delegation» left right int choice (completed) (cancelled) cancel (asynchronously)Namely, (1) it has an improved fluent interface (i.e., method calls can be chained) via C#'s out variables, reducing the risk of linearity violation in an idiomatic way. Furthermore, (2) it enables session cancellation in a limited form -which we call session intervention -by utilising amalgamation of C#'s async/await and session delegation in thread-based concurrency. We illustrate the essential bits of SessionC# where a cancellable computation is guided by session types, by a use-case where a C# thread calculates a cancellable tak function which is designed to have a long running time [20]. The figure on the right depicts the overall communication protocol, which can be written in SessionC# as a protocol specification describing a client-server communication protocol from the client's viewpoint, as follows: var prot = Send(Val<(int,int,int)>, Deleg(chan:Recv(Unit,...

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Section: Discussionmentioning

confidence: 99%

Section: Recursive Sessions Flatlymentioning

confidence: 99%

Section: B More On Recursion and Delegationmentioning

confidence: 99%

Section: A Protocol Combinatorsmentioning

confidence: 99%

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Fluent Session Programming in C#

Kimura

Imai

2020

Electron. Proc. Theor. Comput. Sci.

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“…EDSL EDSLs have been realised for: Haskell [36,30,35]; Go [25]; and Rust [22]. These approaches follow our approach, however, the host language chosen is not as expressive in describing global session description and thus do not allow for reasoning on message descriptions.…”

Section: Related Workmentioning

confidence: 99%

Value-Dependent Session Design in a Dependently Typed Language

Muijnck-Hughes

Brady

Vanderbauwhede

2019

Electron. Proc. Theor. Comput. Sci.

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Session Types offer a typing discipline that allows protocol specifications to be used during typechecking, ensuring that implementations adhere to a given specification. When looking to realise global session types in a dependently typed language care must be taken that values introduced in the description are used by roles that know about the value.We present Sessions, a Resource Dependent Embedded Domain Specific Language (EDSL) for describing global session descriptions in the dependently typed language Idris. As we construct session descriptions the values parameterising the EDSLs' type keeps track of roles and messages they have encountered. We can use this knowledge to ensure that message values are only used by those who know the value. Sessions supports protocol descriptions that are computable, composable, higher-order, and value-dependent. We demonstrate Sessions expressiveness by describing the TCP Handshake, a multi-modal server providing echo and basic arithmetic operations, and a Higher-Order protocol that supports an authentication interaction step.

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Relating Functional and Imperative Session Types

Saffrich

Thiemann

2021

Lecture Notes in Computer Science

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Haskell session types with (almost) no class

Cited by 66 publications

References 24 publications

Fluent Session Programming in C#

Fluent Session Programming in C#

Value-Dependent Session Design in a Dependently Typed Language

Relating Functional and Imperative Session Types

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