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Purerl-Cookbook Documentation
purerl-cookbook Documentation Rob Ashton Jun 17, 2021 Contents 1 The build process 3 1.1 Purerl (Server) Build...........................................3 1.2 Erlang (Server) Build..........................................3 1.3 Purescript (Client) Build.........................................4 2 Editors 9 2.1 Other editors...............................................9 3 Skeleton 13 3.1 Erlang.................................................. 13 3.2 Purerl................................................... 15 3.3 Purescript................................................. 17 4 Basic OTP 19 4.1 OTP Entry Point............................................. 19 4.2 OTP Supervisor............................................. 20 4.3 OTP Gen server............................................. 22 4.4 Dynamic Supervision Trees....................................... 23 5 Web Server 25 5.1 Stetson.................................................. 25 5.2 Stetson Routing............................................. 26 5.3 Stetson Handlers............................................. 28 5.4 Stetson Websockets........................................... 29 5.5 Stetson Streaming............................................ 30 6 Logging 33 6.1 Lager................................................... 33 6.2 Logger.................................................. 34 7 Messaging 37 7.1 Subscribing to Incoming messages (pseudo-example).......................... 37 7.2 Sending Outgoing Messages (pseudo example)............................. 38 8 Interop 47 8.1 -
Marcelo Camargo (Haskell Camargo) – Résumé Projects
Marcelo Camargo (Haskell Camargo) – Résumé https://github.com/haskellcamargo [email protected] http://coderbits.com/haskellcamargo Based in Joinville / SC – Brazil Knowledge • Programming languages domain: ◦ Ada, AdvPL, BASIC, C, C++, C#, Clipper, Clojure, CoffeeScript, Common LISP, Elixir, Erlang, F#, FORTRAN, Go, Harbour, Haskell, Haxe, Hy, Java, JavaScript, Ink, LiveScript, Lua, MATLAB, Nimrod, OCaml, Pascal, PHP, PogoScript, Processing, PureScript, Python, Ruby, Rust, Self, Shell, Swift, TypeScript, VisualBasic [.NET], Whip, ZPL. • Markup, style and serialization languages: ◦ Markdown, reStructuredText, [X] HTML, XML, CSS, LESS, SASS, Stylus, Yaml, JSON, DSON. • Database management systems: ◦ Oracle, MySQL, SQL Server, IBM DB2, PostgreSQL. • Development for operating systems: ◦ Unix based, Windows (CE mobile included), Android, Firefox OS. • Parsers and compilers: ◦ Macros: ▪ Sweet.js, preprocessor directives. ◦ Parser and scanner generators: ▪ ANTLR, PEG.js, Jison, Flex, re2c, Lime. • Languages: ◦ Portuguese (native) ◦ English (native) ◦ Spanish (fluent) ◦ French (fluent) ◦ Turkish (intermediate) ◦ Chinese (mandarin) (intermediate) ◦ Esperanto (intermediate) Projects • Prelude AdvPL – a library that implements functional programming in AdvPL and extends its syntax to a more expressive one; it's a port of Haskell's Prelude; • Frida – a LISP dialect that runs on top of Node.js; • PHPP – A complete PHP preprocessor with a grammar able to identify and replace tokens and extend/modify the language syntax, meant to be implemented -
Bisimulations for Delimited-Control Operators
Logical Methods in Computer Science Volume 15, Issue 2, 2019, pp. 18:1–18:57 Submitted Apr. 24, 2018 https://lmcs.episciences.org/ Published May 24, 2019 BISIMULATIONS FOR DELIMITED-CONTROL OPERATORS DARIUSZ BIERNACKI a, SERGUE¨I LENGLET b, AND PIOTR POLESIUK a a University of Wroclaw e-mail address: fdabi,[email protected] b Universit´ede Lorraine e-mail address: [email protected] Abstract. We present a comprehensive study of the behavioral theory of an untyped λ-calculus extended with the delimited-control operators shift and reset. To that end, we define a contextual equivalence for this calculus, that we then aim to characterize with coinductively defined relations, called bisimilarities. We consider different styles of bisimilarities (namely applicative, normal-form, and environmental) within a unifying framework, and we give several examples to illustrate their respective strengths and weaknesses. We also discuss how to extend this work to other delimited-control operators. 1. Introduction Delimited-control operators. Control operators for delimited continuations enrich a pro- gramming language with the ability to delimit the current continuation, to capture such a delimited continuation, and to compose delimited continuations. Such operators have been originally proposed independently by Felleisen [26] and by Danvy and Filinski [21], with nu- merous variants designed subsequently [34, 66, 32, 25]. The applications of delimited-control operators range from non-deterministic programming [21, 45], partial evaluation [58, 19], and normalization by evaluation [24] to concurrency [34], mobile code [89], linguistics [84], oper- ating systems [43], and probabilistic programming [44]. Several variants of delimited-control operators are nowadays available in mainstream functional languages such as Haskell [25], OCaml [42], Racket [29], and Scala [76]. -
An Operational Foundation for Delimited Continuations in the Cps Hierarchy
Logical Methods in Computer Science Vol. 1 (2:5) 2005, pp. 1–39 Submitted Apr. 1, 2005 www.lmcs-online.org Published Nov. 8, 2005 AN OPERATIONAL FOUNDATION FOR DELIMITED CONTINUATIONS IN THE CPS HIERARCHY MALGORZATA BIERNACKA, DARIUSZ BIERNACKI, AND OLIVIER DANVY BRICS, Department of Computer Science, University of Aarhus IT-parken, Aabogade 34, DK-8200 Aarhus N, Denmark e-mail address: {mbiernac,dabi,danvy}@brics.dk Abstract. We present an abstract machine and a reduction semantics for the lambda- calculus extended with control operators that give access to delimited continuations in the CPS hierarchy. The abstract machine is derived from an evaluator in continuation- passing style (CPS); the reduction semantics (i.e., a small-step operational semantics with an explicit representation of evaluation contexts) is constructed from the abstract machine; and the control operators are the shift and reset family. We also present new applications of delimited continuations in the CPS hierarchy: finding list prefixes and normalization by evaluation for a hierarchical language of units and products. 1. Introduction The studies of delimited continuations can be classified in two groups: those that use continuation-passing style (CPS) and those that rely on operational intuitions about con- trol instead. Of the latter, there is a large number proposing a variety of control opera- tors [5,37,40,41,49,52,53,65,70,74,80] which have found applications in models of control, concurrency, and type-directed partial evaluation [8,52,75]. Of the former, there is the work revolving around the family of control operators shift and reset [27–29,32,42,43,55,56,66,80] which have found applications in non-deterministic programming, code generation, par- tial evaluation, normalization by evaluation, computational monads, and mobile comput- ing [6,7,9,17,22,23,33,34,44,46,48,51,57,59,61,72,77–79]. -
Education Social
Jens Krause Hamburg Area - Germany | http://jkrause.io | [email protected] Independent Software Developer with ~20 years of experiences in the industry. Today focused on building software in the crypto and blockchain space by using Functional Programming (Haskell, PureScript, Rust etc). Contract work (Detailed portfolio: http://jkrause.io/arbeiten/) 2016 - 2019 Blockchain development LNX Senior Blockchain Architect Seoul / South Korea - Prepare DAG part to work with Substrate May 2019 – August 2019 - p2p handling of DAG nodes independently of Substrate (libp2p, Rust) (contract + remote work) - e2e / unit tests (Rust) - Basic architecture of LNX wallet (Vue.js, Vuex, polkadot.js, TypeScript) FOAM Senior Blockchain Developer New York / USA - Front- and backend development of a TCR (Ethereum) based world map April 2018 – April 2019 http://map.foam.space (PureScript, Haskell) (contract + remote work) - PoC of Plasma MVP implementation with Cosmos (Go, PureScript) - Misc. (e2e, unit tests, Solidity) IOHK Cardano SL Developer – Team Haskell Hong Kong - Front- and backend development of Cardano‘s blockchain explorer Dec. 2016 – April 2018 https://cardanoexplorer.com (PureScript, Haskell) (contract + remote work) - Re-write of Daedalus wallet API (Haskell) - Developing API layer to bridge Daedalus wallet (PureScript) - Testing and re-factoring of Cardano-SL (Haskell) - Misc. PoC‘s (e.g. type generator Haskell to PureScript) 2012 - 2016 Web-, Mobile development Misc. projects / clients Senior Developer Cellular, SinnerSchrader, - Web / Mobile applications (Angular, Backbone, Ionic, Knockout, React, misc. startups, Volkswagen, React Native, RxJS, TypeScript, CoffeeScript, ES 6/7, RubyMotion) ZDF, TUI, etc. - Backend development (NodeJS, PHP, Zend, RabbitMQ, Ruby) - TDD / BDD / E2E (Karma, Istanbul, Mocha, Sinon, Enzyme, Webdriver, CucumberJS) 1999 - 2012 Web-, Desktop-, Mobile development Misc. -
Curriculum Vitae
Diogo Castro Curriculum Vitae Summary I’m a Software Engineer based in Belfast, United Kingdom. My professional journey began as a C# developer, but Functional Programming (FP) soon piqued my interest and led me to learn Scala, Haskell, PureScript and even a bit of Idris. I love building robust, reliable and maintainable applications. I also like teaching and I’m a big believer in "paying it forward". I’ve learned so much from many inspiring people, so I make it a point to share what I’ve learned with others. To that end, I’m currently in charge of training new team members in Scala and FP, do occasional presentations at work and aim to do more public speaking. I blog about FP and Haskell at https://diogocastro.com/blog. Experience Nov 2017-Present Principal Software Engineer, SpotX, Belfast, UK. Senior Software Engineer, SpotX, Belfast, UK. Developed RESTful web services in Scala, using the cats/cats-effect framework and Akka HTTP. Used Apache Kafka for publishing of events, and Prometheus/Grafana for monitor- ing. Worked on a service that aimed to augment Apache Druid, a timeseries database, with features such as access control, a safer and simpler query DSL, and automatic conversion of monetary metrics to multiple currencies. Authored a Scala library for calculating the delta of any two values of a given type using Shapeless, a library for generic programming. Taught a weekly internal Scala/FP course, with the goal of preparing our engineers to be productive in Scala whilst building an intuition of how to program with functions and equational reasoning. -
Continuation Passing Style for Effect Handlers
Continuation Passing Style for Effect Handlers Daniel Hillerström1, Sam Lindley2, Robert Atkey3, and KC Sivaramakrishnan4 1 The University of Edinburgh, United Kingdom [email protected] 2 The University of Edinburgh, United Kingdom [email protected] 3 University of Strathclyde, United Kingdom [email protected] 4 University of Cambridge, United Kingdom [email protected] Abstract We present Continuation Passing Style (CPS) translations for Plotkin and Pretnar’s effect han- dlers with Hillerström and Lindley’s row-typed fine-grain call-by-value calculus of effect handlers as the source language. CPS translations of handlers are interesting theoretically, to explain the semantics of handlers, and also offer a practical implementation technique that does not require special support in the target language’s runtime. We begin with a first-order CPS translation into untyped lambda calculus which manages a stack of continuations and handlers as a curried sequence of arguments. We then refine the initial CPS translation first by uncurrying it to yield a properly tail-recursive translation and second by making it higher-order in order to contract administrative redexes at translation time. We prove that the higher-order CPS translation simulates effect handler reduction. We have implemented the higher-order CPS translation as a JavaScript backend for the Links programming language. 1998 ACM Subject Classification D.3.3 Language Constructs and Features, F.3.2 Semantics of Programming Languages Keywords and phrases effect handlers, delimited control, continuation passing style Digital Object Identifier 10.4230/LIPIcs.FSCD.2017.18 1 Introduction Algebraic effects, introduced by Plotkin and Power [25], and their handlers, introduced by Plotkin and Pretnar [26], provide a modular foundation for effectful programming. -
Communication-Safe Web Programming in Typescript with Routed Multiparty Session Types
Communication-Safe Web Programming in TypeScript with Routed Multiparty Session Types Anson Miu Francisco Ferreira Imperial College London and Bloomberg Imperial College London United Kingdom United Kingdom Nobuko Yoshida Fangyi Zhou Imperial College London Imperial College London United Kingdom United Kingdom Abstract ACM Reference Format: Modern web programming involves coordinating interac- Anson Miu, Francisco Ferreira, Nobuko Yoshida, and Fangyi Zhou. tions between browser clients and a server. Typically, the 2021. Communication-Safe Web Programming in TypeScript with Routed Multiparty Session Types. In Proceedings of the 30th ACM interactions in web-based distributed systems are informally SIGPLAN International Conference on Compiler Construction (CC ’21), described, making it hard to ensure correctness, especially March 2–3, 2021, Virtual, USA. ACM, New York, NY, USA, 27 pages. communication safety, i.e. all endpoints progress without https://doi.org/10.1145/3446804.3446854 type errors or deadlocks, conforming to a specified protocol. We present STScript, a toolchain that generates TypeScript 1 Introduction APIs for communication-safe web development over Web- Web technology advancements have changed the way peo- Sockets, and RouST, a new session type theory that supports ple use computers. Many services that required standalone multiparty communications with routing mechanisms. applications, such as email, chat, video conferences, or even STScript provides developers with TypeScript APIs gen- games, are now provided in a browser. While the Hypertext erated from a communication protocol specification based Transfer Protocol (HTTP) is widely used for serving web on RouST. The generated APIs build upon TypeScript con- pages, its Request-Response model limits the communication currency practices, complement the event-driven style of patterns — the server may not send data to a client without programming in full-stack web development, and are com- the client first making a request. -
Delimited Continuations in Operating Systems
Delimited continuations in operating systems Oleg Kiselyov1 and Chung-chieh Shan2 1 FNMOC [email protected] 2 Rutgers University [email protected] Abstract. Delimited continuations are the meanings of delimited evalu- ation contexts in programming languages. We show they offer a uniform view of many scenarios that arise in systems programming, such as a re- quest for a system service, an event handler for input/output, a snapshot of a process, a file system being read and updated, and a Web page. Ex- plicitly recognizing these uses of delimited continuations helps us design a system of concurrent, isolated transactions where desirable features such as snapshots, undo, copy-on-write, reconciliation, and interposition fall out by default. It also lets us take advantage of efficient implemen- tation techniques from programming-language research. The Zipper File System prototypes these ideas. 1 Introduction One notion of context that pervades programming-language research is that of evaluation contexts. If one part of a program is currently running (that is, being evaluated), then the rest of the program is expecting the result from that part, typically waiting for it. This rest of the program is the evaluation context of the running part. For example, in the program “1 + 2 × 3”, the evaluation context of the multiplication “2 × 3” is the rest of the program “1 + ”. The meaning of an evaluation context is a function that maps a result value to an answer. For example, the meaning of the evaluation context “1 + ” is the increment function, so it maps the result value 6 to the answer 7. -
Delimited Control with Multiple Prompts in Theory and Practice
Delimited control with multiple prompts in theory and practice Paul Downen Zena M. Ariola University of Oregon fpdownen,[email protected] 1. Proposal hE[S V ]i 7! hV (λx.hE[x]i)i The versatile and expressive capabilities of delimited control and composable continuations have gained it attention in both the the- #(E[F V ]) 7! #(V (λx.E[x])) ory and practice of functional programming with effects. On the hE[S0 V ]i0 7! V (λx.hE[x]i0) more theoretical side, delimited control may be used as a basis for # (E[F V ]) 7! V (λx.E[x]) explaining and understanding a wide variety of other computational 0 0 effects, like mutable state and exceptions, based on Filinski’s [8, 9] observation that composable continuations can be used to repre- Figure 1. Four different pairs of delimiters and control operators. sent any monadic effect. On the more practical side, forms of de- limited control have been implemented in real-world programming languages [6, 10, 15], and used in the design of libraries like for represents a closed off sub-computation, where the F operator is creating web servers [10]. only capable of capturing the evaluation context 2 × ≤ 10. That However, the design space for adding composable continua- way, the delimiter protects the surrounding context from the control tions to a programming language is vast, and a number of dif- operator, so that even in the larger program ferent definitions of delimited control operators have been pro- if #(2 × (F (λk:M)) ≤ 10) then red else blue posed [3, 4, 7, 12, 21]. -
Backpropagation with Continuation Callbacks: Foundations for Efficient
Backpropagation with Continuation Callbacks: Foundations for Efficient and Expressive Differentiable Programming Fei Wang James Decker Purdue University Purdue University West Lafayette, IN 47906 West Lafayette, IN 47906 [email protected] [email protected] Xilun Wu Grégory Essertel Tiark Rompf Purdue University Purdue University Purdue University West Lafayette, IN 47906 West Lafayette, IN, 47906 West Lafayette, IN, 47906 [email protected] [email protected] [email protected] Abstract Training of deep learning models depends on gradient descent and end-to-end differentiation. Under the slogan of differentiable programming, there is an increas- ing demand for efficient automatic gradient computation for emerging network architectures that incorporate dynamic control flow, especially in NLP. In this paper we propose an implementation of backpropagation using functions with callbacks, where the forward pass is executed as a sequence of function calls, and the backward pass as a corresponding sequence of function returns. A key realization is that this technique of chaining callbacks is well known in the programming languages community as continuation-passing style (CPS). Any program can be converted to this form using standard techniques, and hence, any program can be mechanically converted to compute gradients. Our approach achieves the same flexibility as other reverse-mode automatic differ- entiation (AD) techniques, but it can be implemented without any auxiliary data structures besides the function call stack, and it can easily be combined with graph construction and native code generation techniques through forms of multi-stage programming, leading to a highly efficient implementation that combines the per- formance benefits of define-then-run software frameworks such as TensorFlow with the expressiveness of define-by-run frameworks such as PyTorch. -
A Rational Deconstruction of Landin's J Operator
BRICS RS-06-4 Danvy & Millikin: A Rational Deconstruction of Landin’s J Operator BRICS Basic Research in Computer Science A Rational Deconstruction of Landin’s J Operator Olivier Danvy Kevin Millikin BRICS Report Series RS-06-4 ISSN 0909-0878 February 2006 Copyright c 2006, Olivier Danvy & Kevin Millikin. BRICS, Department of Computer Science University of Aarhus. All rights reserved. Reproduction of all or part of this work is permitted for educational or research use on condition that this copyright notice is included in any copy. See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained by contacting: BRICS Department of Computer Science University of Aarhus IT-parken, Aabogade 34 DK–8200 Aarhus N Denmark Telephone: +45 8942 9300 Telefax: +45 8942 5601 Internet: [email protected] BRICS publications are in general accessible through the World Wide Web and anonymous FTP through these URLs: http://www.brics.dk ftp://ftp.brics.dk This document in subdirectory RS/06/4/ A Rational Deconstruction of Landin’s J Operator∗ Olivier Danvy and Kevin Millikin BRICS† Department of Computer Science University of Aarhus‡ February 28, 2006 Abstract Landin’s J operator was the first control operator for functional languages, and was specified with an extension of the SECD machine. Through a se- ries of meaning-preserving transformations (transformation into continu- ation-passing style (CPS) and defunctionalization) and their left inverses (transformation into direct style and refunctionalization), we present a compositional evaluation function corresponding to this extension of the SECD machine. We then characterize the J operator in terms of CPS and in terms of delimited-control operators in the CPS hierarchy.