Four Lectures on Standard ML
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Type-Safe Multi-Tier Programming with Standard ML Modules
Experience Report: Type-Safe Multi-Tier Programming with Standard ML Modules Martin Elsman Philip Munksgaard Ken Friis Larsen Department of Computer Science, iAlpha AG, Switzerland Department of Computer Science, University of Copenhagen, Denmark [email protected] University of Copenhagen, Denmark [email protected] kfl[email protected] Abstract shared module, it is now possible, on the server, to implement a We describe our experience with using Standard ML modules and module that for each function responds to a request by first deseri- Standard ML’s core language typing features for ensuring type- alising the argument into a value, calls the particular function and safety across physically separated tiers in an extensive web applica- replies to the client with a serialised version of the result value. tion built around a database-backed server platform and advanced Dually, on the client side, for each function, the client code can client code that accesses the server through asynchronous server serialise the argument and send the request asynchronously to the requests. server. When the server responds, the client will deserialise the re- sult value and apply the handler function to the value. Both for the server part and for the client part, the code can be implemented in 1. Introduction a type-safe fashion. In particular, if an interface type changes, the The iAlpha Platform is an advanced asset management system programmer will be notified about all type-inconsistencies at com- featuring a number of analytics modules for combining trading pile -
Understanding and Evolving the ML Module System
Understanding and Evolving the ML Module System Derek Dreyer May 2005 CMU-CS-05-131 School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213 Thesis Committee: Robert Harper (co-chair) Karl Crary (co-chair) Peter Lee David MacQueen (University of Chicago) Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy Copyright c 2005 Derek Dreyer This research was sponsored in part by the National Science Foundation under grant CCR-0121633 and EIA- 9706572, and the US Air Force under grant F19628-95-C-0050 and a generous fellowship. The views and conclusions contained in this document are those of the author and should not be interpreted as representing the official policies, either expressed or implied, of any sponsoring institution, the U.S. government or any other entity. Keywords: ML, module systems, type systems, functors, abstract data types, lambda calculus, recursive modules, singleton kinds Abstract The ML module system stands as a high-water mark of programming language support for data abstraction. Nevertheless, it is not in a fully evolved state. One prominent weakness is that module interdependencies in ML are restricted to be acyclic, which means that mutually recursive functions and data types must be written in the same module even if they belong conceptually in different modules. Existing efforts to remedy this limitation either involve drastic changes to the notion of what a module is, or fail to allow mutually recursive modules to hide type information from one another. Another issue is that there are several dialects of ML, and the module systems of these dialects differ in subtle yet semantically significant ways that have been difficult to account for in any rigorous way. -
A Separate Compilation Extension to Standard ML
A Separate Compilation Extension to Standard ML David Swasey Tom Murphy VII Karl Crary Robert Harper Carnegie Mellon {swasey,tom7,crary,rwh}@cs.cmu.edu Abstract The goal of this work is to consolidate and synthesize previ- We present an extension to Standard ML, called SMLSC, to support ous work on compilation management for ML into a formally de- separate compilation. The system gives meaning to individual pro- fined extension to the Standard ML language. The extension itself gram fragments, called units. Units may depend on one another in a is syntactically and conceptually very simple. A unit is a series of way specified by the programmer. A dependency may be mediated Standard ML top-level declarations, given a name. To the current by an interface (the type of a unit); if so, the units can be compiled top-level declarations such as structure and functor we add an separately. Otherwise, they must be compiled in sequence. We also import declaration that is to units what the open declaration is to propose a methodology for programming in SMLSC that reflects structures. An import declaration may optionally specify an inter- code development practice and avoids syntactic repetition of inter- face for the unit, in which case we are able to compile separately faces. The language is given a formal semantics, and we argue that against that dependency; with no interface we must compile incre- this semantics is implementable in a variety of compilers. mentally. Compatibility with existing compilers, including whole- program compilers, is assured by making no commitment to the Categories and Subject Descriptors D.3.3 [Programming Lan- precise meaning of “compile” and “link”—a compiler is free to guages]: Language Constructs and Features—Modules, pack- limit compilation to elaboration and type checking, and to perform ages; D.3.1 [Programming Languages]: Formal Definitions and code generation as part of linking. -
Functional Programming (ML)
Functional Programming CSE 215, Foundations of Computer Science Stony Brook University http://www.cs.stonybrook.edu/~cse215 Functional Programming Function evaluation is the basic concept for a programming paradigm that has been implemented in functional programming languages. The language ML (“Meta Language”) was originally introduced in the 1970’s as part of a theorem proving system, and was intended for describing and implementing proof strategies. Standard ML of New Jersey (SML) is an implementation of ML. The basic mode of computation in SML is the use of the definition and application of functions. 2 (c) Paul Fodor (CS Stony Brook) Install Standard ML Download from: http://www.smlnj.org Start Standard ML: Type ''sml'' from the shell (run command line in Windows) Exit Standard ML: Ctrl-Z under Windows Ctrl-D under Unix/Mac 3 (c) Paul Fodor (CS Stony Brook) Standard ML The basic cycle of SML activity has three parts: read input from the user, evaluate it, print the computed value (or an error message). 4 (c) Paul Fodor (CS Stony Brook) First SML example SML prompt: - Simple example: - 3; val it = 3 : int The first line contains the SML prompt, followed by an expression typed in by the user and ended by a semicolon. The second line is SML’s response, indicating the value of the input expression and its type. 5 (c) Paul Fodor (CS Stony Brook) Interacting with SML SML has a number of built-in operators and data types. it provides the standard arithmetic operators - 3+2; val it = 5 : int The Boolean values true and false are available, as are logical operators such as not (negation), andalso (conjunction), and orelse (disjunction). -
Robert Harper Carnegie Mellon University
The Future Of Standard ML Robert Harper Carnegie Mellon University Sunday, September 22, 13 Whither SML? SML has been hugely influential in both theory and practice. The world is slowly converging on ML as the language of choice. There remain big opportunities to be exploited in research and education. Sunday, September 22, 13 Convergence The world moves inexorably toward ML. Eager, not lazy evaluation. Static, not dynamic, typing. Value-, not object-, oriented. Modules, not classes. Every new language is more “ML-like”. Sunday, September 22, 13 Convergence Lots of ML’s and ML-like languages being developed. O’Caml, F#, Scala, Rust SML#, Manticore O’Caml is hugely successful in both research and industry. Sunday, September 22, 13 Convergence Rich typing supports verification. Polytyping >> Unityping Not all types are pointed. Useful cost model, especially for parallelism and space usage. Modules are far better than objects. Sunday, September 22, 13 Standard ML Standard ML remains important as a vehicle for teaching and research. Intro CS @ CMU is in SML. Lots of extensions proposed. We should consolidate advances and move forward. Sunday, September 22, 13 Standard ML SML is a language, not a compiler! It “exists” as a language. Stable, definitive criterion for compatibility. Having a semantics is a huge asset, provided that it can evolve. Sunday, September 22, 13 Standard ML At least five compatible compilers: SML/NJ, PolyML, MLKit, MosML, MLton, MLWorks (?). Several important extensions: CML, SML#, Manticore, SMLtoJS, ParallelSML (and probably more). Solid foundation on which to build and develop. Sunday, September 22, 13 The Way Forward Correct obvious shortcomings. -
Lecture Notes in Computer Science 2566 Edited by G
Lecture Notes in Computer Science 2566 Edited by G. Goos, J. Hartmanis, and J. van Leeuwen 3 Berlin Heidelberg New York Barcelona Hong Kong London Milan Paris Tokyo Torben Æ. Mogensen David A. Schmidt I. Hal Sudborough (Eds.) The Essence of Computation Complexity, Analysis, Transformation Essays Dedicated to Neil D. Jones 13 Series Editors Gerhard Goos, Karlsruhe University, Germany Juris Hartmanis, Cornell University, NY, USA Jan van Leeuwen, Utrecht University, The Netherlands Volume Editors Torben Æ. Mogensen University of Copenhagen, DIKU Universitetsparken 1, 2100 Copenhagen, Denmark E-mail: [email protected] David A. Schmidt Kansas State University, Department of Computing and Information Sciences 234 Nichols Hall, Manhattan, KS 66506 USA E-mail: [email protected] I. Hal Sudborough University of Texas at Dallas, Department of Computer Science P.O. Box 830688, Richardson, TX 75083 USA E-mail: [email protected] The illustration appearing on the cover of this book is the work of Daniel Rozenberg (DADARA). Cataloging-in-Publication Data applied for A catalog record for this book is available from the Library of Congress. Bibliographic information published by Die Deutsche Bibliothek. Die Deutsche Bibliothek lists this publication in the Deutsche Nationalbibliografie; detailed bibliographic data is available in the Internet at <http://dnb.ddb.de>. CR Subject Classification (1998): F.3, F.1, D.2 ISSN 0302-9743 ISBN 3-540-00326-6 Springer-Verlag Berlin Heidelberg New York This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, re-use of illustrations, recitation, broadcasting, reproduction on microfilms or in any other way, and storage in data banks. -
Standard ML Mini-Tutorial [1Mm] (In Particular SML/NJ)
Standard ML Mini-tutorial (in particular SML/NJ) Programming Languages CS442 David Toman School of Computer Science University of Waterloo David Toman (University of Waterloo) Standard ML 1 / 21 Introduction • SML (Standard Meta Language) ⇒ originally part of the LCF project (Gordon et al.) • Industrial strength PL (SML’90, SML’97) ⇒ based formal semantics (Milner et al.) • SML “Basis Library” (all you ever wanted) ⇒ based on advanced module system • Quality compilers: ⇒ SML/NJ (Bell Labs) ⇒ Moscow ML David Toman (University of Waterloo) Standard ML 2 / 21 Features • Everything is built from expressions ⇒ functions are first class citizens ⇒ pretty much extension of our simple functional PL • Support for structured values: lists, trees, . • Strong type system ⇒ let-polymorphic functions ⇒ type inference • Powerful module system ⇒ signatures, implementations, ADTs,. • Imperative features (e.g., I/O) David Toman (University of Waterloo) Standard ML 3 / 21 Tutorial Goals 1 Make link from our functional language to SML 2 Provide enough SML syntax and examples for A2 • How to use SML/NJ interactive environment • How to write simple functional programs • How to define new data types • How to understand compiler errors • Where to find more information 3 Show type inference in action (so we understand what’s coming) David Toman (University of Waterloo) Standard ML 4 / 21 Getting started • Starting it up: sml in UNIX (click somewhere in W/XP) Example Standard ML of New Jersey, Version 110.0.7 [CM&CMB] - ⇒ great support in Emacs • Notation and simple -
SML# JSON Support
A Calculus with Partially Dynamic Records for Typeful Manipulation of JSON Objects∗ Atsushi Ohori1,2, Katsuhiro Ueno1,2, Tomohiro Sasaki1,2, and Daisuke Kikuchi1,3 1 Research Institute of Electrical Communication, Tohoku University Sendai, Miyagi, 980-8577, Japan {ohori,katsu,tsasaki,kikuchi}@riec.tohoku.ac.jp 2 Graduate School of Information Sciences, Tohoku University Sendai, Miyagi, 980-8579, Japan 3 Hitachi Solutions East Japan, Ltd. Sendai, Miyagi, 980-0014, Japan [email protected] Abstract This paper investigates language constructs for high-level and type-safe manipulation of JSON objects in a typed functional language. A major obstacle in representing JSON in a static type system is their heterogeneous nature: in most practical JSON APIs, a JSON array is a heterogeneous list consisting of, for example, objects having common fields and possibly some optional fields. This paper presents a typed calculus that reconciles static typing constraints and heterogeneous JSON arrays based on the idea of partially dynamic records originally proposed and sketched by Buneman and Ohori for complex database object manipulation. Partially dynamic records are dynamically typed records, but some parts of their structures are statically known. This feature enables us to represent JSON objects as typed data structures. The proposed calculus smoothly extends with ML-style pattern matching and record polymorphism. These results yield a typed functional language where the programmer can directly import JSON data as terms having static types, and can manipulate them with the full benefits of static polymorphic type-checking. The proposed calculus has been embodied in SML#, an extension of Standard ML with record polymorphism and other practically useful features. -
Haskell-Like S-Expression-Based Language Designed for an IDE
Department of Computing Imperial College London MEng Individual Project Haskell-Like S-Expression-Based Language Designed for an IDE Author: Supervisor: Michal Srb Prof. Susan Eisenbach June 2015 Abstract The state of the programmers’ toolbox is abysmal. Although substantial effort is put into the development of powerful integrated development environments (IDEs), their features often lack capabilities desired by programmers and target primarily classical object oriented languages. This report documents the results of designing a modern programming language with its IDE in mind. We introduce a new statically typed functional language with strong metaprogramming capabilities, targeting JavaScript, the most popular runtime of today; and its accompanying browser-based IDE. We demonstrate the advantages resulting from designing both the language and its IDE at the same time and evaluate the resulting environment by employing it to solve a variety of nontrivial programming tasks. Our results demonstrate that programmers can greatly benefit from the combined application of modern approaches to programming tools. I would like to express my sincere gratitude to Susan, Sophia and Tristan for their invaluable feedback on this project, my family, my parents Michal and Jana and my grandmothers Hana and Jaroslava for supporting me throughout my studies, and to all my friends, especially to Harry whom I met at the interview day and seem to not be able to get rid of ever since. ii Contents Abstract i Contents iii 1 Introduction 1 1.1 Objectives ........................................ 2 1.2 Challenges ........................................ 3 1.3 Contributions ...................................... 4 2 State of the Art 6 2.1 Languages ........................................ 6 2.1.1 Haskell .................................... -
Using Domain Specific Language for Modeling and Simulation: Scalation As a Case Study
Proceedings of the 2010 Winter Simulation Conference B. Johansson, S. Jain, J. Montoya-Torres, J. Hugan, and E. Yucesan,¨ eds. USING DOMAIN SPECIFIC LANGUAGE FOR MODELING AND SIMULATION: SCALATION AS A CASE STUDY John A. Miller Jun Han Maria Hybinette Department of Computer Science University of Georgia Athens, GA, 30602, USA ABSTRACT Progress in programming paradigms and languages has over time influenced the way that simulation programs are written. Modern object-oriented, functional programming languages are expressive enough to define embedded Domain Specific Languages (DSLs). The Scala programming language is used to implement ScalaTion that supports several popular simulation modeling paradigms. As a case study, ScalaTion is used to consider how language features of object-oriented, functional programming languages and Scala in particular can be used to write simulation programs that are clear, concise and intuitive to simulation modelers. The dichotomy between “model specification” and “simulation program” is also considered both historically and in light of the potential narrowing of the gap afforded by embedded DSLs. 1 INTRODUCTION As one learns simulation the importance of the distinction between “model specification” and “simulation program” is made clear. In the initial period (Nance 1996), the distinction was indeed important as models were expressed in a combination of natural language (e.g., English) and mathematics, while the simulation programs implementing the models were written in Fortran. The gap was huge. Over time, the gap has narrowed through the use of more modern general-purpose programming languages (GPLs) with improved readability and conciseness. Besides advances in general-purpose languages, the developers of Simulation Programming Languages (SPLs) have made major contributions. -
A Simpli Ed Account of Polymorphic References 1 Introduction 2 a Language with Mutable Data Structures
A Simpli ed AccountofPolymorphic References Rob ert Harp er Scho ol of Computer Science Carnegie Mellon University Pittsburgh, PA 15213-3891 Abstract A pro of of the soundness of Tofte's imp erativetyp e discipli ne with resp ect to a structured op erational semantics is given. The presentation is based on a semantic formalism that combines the b ene ts of the approaches considered byWright and Felleisen, and byTofte, leading to a particularly simple pro of of soundness of Tofte's typ e disciplin e. Keywords: formal semantics, functional programming, programming languages, typ e theory, refer- ences and assignment. 1 Intro duction The extension of Damas and Milner's p olymorphic typ e system for pure functional programs [2] to accomo- date mutable cells has proved to b e problematic. The nave extension of the pure language with op erations to allo cate a cell, and to retrieve and mo dify its contents is unsound [11]. The problem has received consid- erable attention, notably by Damas [3], Tofte [10,11], and LeroyandWeiss [7]. Tofte's solution is based on a greatest xed p oint construction to de ne the semantic typing relation [11] (see also [8]). This metho d has b een subsequently used by Leroy and Weiss [7]andTalpin and Jouvelot [9]. It was subsequently noted by Wright and Felleisen [13] that the pro of of soundness can b e substantially simpli ed if the argument is made by induction on the length of an execution sequence, rather than on the structure of the typing derivation. Using this metho d they establish the soundness of a restriction of the language to require that let-b ound expressions b e values. -
The Definition of Standard ML, Revised
The Definition of Standard ML The Definition of Standard ML (Revised) Robin Milner, Mads Tofte, Robert Harper and David MacQueen The MIT Press Cambridge, Massachusetts London, England c 1997 Robin Milner All rights reserved. No part of this book may be reproduced in any form by any electronic or mechanical means (including photocopying, recording, or information storage and retrieval) without permission in writing from the publisher. Printed and bound in the United States of America. Library of Congress Cataloging-in-Publication Data The definition of standard ML: revised / Robin Milner ::: et al. p. cm. Includes bibliographical references and index. ISBN 0-262-63181-4 (alk. paper) 1. ML (Computer program language) I. Milner, R. (Robin), 1934- QA76.73.M6D44 1997 005:1303|dc21 97-59 CIP Contents 1 Introduction 1 2 Syntax of the Core 3 2.1 Reserved Words . 3 2.2 Special constants . 3 2.3 Comments . 4 2.4 Identifiers . 5 2.5 Lexical analysis . 6 2.6 Infixed operators . 6 2.7 Derived Forms . 7 2.8 Grammar . 7 2.9 Syntactic Restrictions . 9 3 Syntax of Modules 12 3.1 Reserved Words . 12 3.2 Identifiers . 12 3.3 Infixed operators . 12 3.4 Grammar for Modules . 13 3.5 Syntactic Restrictions . 13 4 Static Semantics for the Core 16 4.1 Simple Objects . 16 4.2 Compound Objects . 17 4.3 Projection, Injection and Modification . 17 4.4 Types and Type functions . 19 4.5 Type Schemes . 19 4.6 Scope of Explicit Type Variables . 20 4.7 Non-expansive Expressions . 21 4.8 Closure .