294 papers · page 4 of 15
A classic example of the power of generalized algebraic datatypes (GADTs) to verify a delicate implementation is the type-indexed expression AST. This functional pearl refreshes this example, casting it in modern Haskell using many of GHC's bells and whistles. The Stitch interpre…
Programming time-dependent signals like animations involves expressing both continuous and discrete changes in signal values. The method of functional reactive programming (FRP) represents this simply and effectively as discrete modes of an otherwise continuous signal. In variant…
We present Mu, a domain specific language to describe and develop microservices in Haskell. At its core, Mu provides a type level representation of schemas, which we leverage in various ways. These schemas can be automatically imported from industry-standard interface definition …
We study a simple inductive data type for representing correct-by-construction matrices. Despite its simplicity, it can be used to implement matrix-manipulation algorithms efficiently and safely, performing in some cases faster than existing alternatives even though the algorithm…
Using dependent types in production code is a practical way to eliminate errors. While there are many examples of using dependent Haskell to prove invariants about code, few of these are applied to large scale production systems. Critics claim that dependent types are only useful…
Generic programming libraries have historically traded efficiency in return for convenience, and the generics-sop library is no exception. It offers a simple, uniform, representation of all datatypes precisely as a sum of products, making it easy to write generic functions. We sh…
Algebraic effect handlers offer an alternative to monads to incorporate effects in Haskell. In recent work Xie _et al._ show how to give semantics to effect handlers in terms of plain polymorphic lambda calculus through _evidence translation_. Besides giving precise semantics, th…
Data science applications tend to be built by composing tasks: discrete manipulations of data. These tasks are arranged in directed acyclic graphs, and many frameworks exist within the data science community supporting such a structure, which is called a workflow. In realistic ap…
We present a new type-oriented framework for writing shared memory multithreaded programs that the Haskell type system guarantees are deadlock-free. The implementation wraps all concurrent computation inside a graded monad and assumes a total order is defined between locks. The g…
We explicitly motivate the subtle intricacies of Hinze and Paterson's Finger Tree datastructure, by step-wise refining a naive implementation. The result is a new explanation of how Finger Trees work and why they have the particular structure they have, and also a small simplific…
IoT applications are often developed in programming languages with low-level abstractions, where a seemingly innocent mistake might lead to severe security vulnerabilities. Current IoT development tools make it hard to identify these vulnerabilities as they do not provide end-to-…
This document gives the outline of a system demonstration for the QuickSpec theory exploration tool.
We present a library in Haskell for programming Field Programmable Gate Arrays (FPGAs), including hardware software co-design. Code for software (in C) and hardware (in VHDL) is generated from a single program, along with the code to support communication between hardware and sof…
We present a novel but remarkably simple formulation of formal language grammars in Haskell as functions mapping a record of pro- duction parsers to itself. Thus formulated grammars are first-class objects, composable and reusable. We also provide a simple parser implementation f…
Quantified class constraints have been proposed many years ago to raise the expressive power of type classes from Horn clauses to the universal fragment of Hereditiary Harrop logic. Yet, while it has been much asked for over the years, the feature was never implemented or studied…
This paper presents Speculate, a tool that automatically conjectures laws involving conditional equations and inequalities about Haskell functions. Speculate enumerates expressions involving a given collection of Haskell functions, testing to separate those expressions into appar…
A key part of implementing high-level languages is providing built- in and default data structures. Yet selecting good defaults is hard. A mutable data structure’s workload is not known in advance, and it may shift over its lifetime—e.g., between read-heavy and write- heavy, or f…
Previous work has demonstrated that it is possible to generate efficient and highly parallel code for multicore CPUs and GPUs from combinator-based array languages for a range of applications. That work, however, has been limited to operating on flat, rectangular structures witho…
Monads and applicative functors are two ways that Haskell programmers bundle effectful primitives into effectful program fragments. In this paper, we investigate using monads and applicative functors to bundle remote effectful primitives, specifically aiming to amortize the cost …
We present a domain-specific language for constructing and configuring web applications distributed across any number of networked, heterogeneous systems. Our language is embedded in Haskell, provides a common framework for integrating components written in third-party EDSLs, and…