Product Description
Written by a well-known computerscience education and researcher. No previous knowledge of ML or functionalprogramming is assumed.This is the first book that offersBOTH a highly accessible, step-by-step introductory tutorial on ML programmingand a complete reference to, and explanation of, advanced features. The authoruses a wide variety of digestible program examples to bring the readeralong at a reasonable pace. More sophisticated programs and advanced concepttopics balance out a book that is usable in a number of courses and settingsfor either self-study or class discussion. ... Read more

Customer Reviews (6)

Treasure Map to Understanding ML
When tasked to quickly learn the basics of the ML programming language for class and be expected to program an Abstract Data Type, I was a little bit frantic. In the short time given to me to prep for said programing project, I raced around looking for sources that would improve my understanding of the language and one of the sources i found was this book that was also recommended by the professor.

This book, Elements of ML Programming, has its reader approach ML from the vantage point of either someone who has never programmed but has some understanding of Programming theory or someone who has programmed before but never touched a Functional Programming Language. In that respect it excels at explaining the unique features of the ML language and how best to use and write in it.

****************Good Book But Outdated ****************
This book covers the ML programming language. Unfortunately this language is rarely used these days as a functional programming language . This is a97 edition which is again more than a decade old. If you are a person looking to learn a functional programming language i recommend learning the newer language such as Haskell. I used Haskell for my course recently.

Great intro book.
Examples and exposition are overall great.Jokes are clever and the tone is light through the book.It reads much like the Perl book by Lary Wall.It hits topics a bit slower than SICP.The biggest problem with this book is it left me felling "Ok, I know the syntax/semantics, now what?"This is a common problem with intro to programming books, and I don't fault it too much for that.

The biggest weakness of this book in my opinion is it didn't strongly teach a "style" that I can adopt into my own programs (but then, no FP programming book I've ever read does).It did great teaching functional programming, but as with most intro-to-fp books forgot that real programs don't fit in one file and are several thousand lines of code.

Sean

Academic? Yes, but that's a good thing
I appreciate the consistency of exposition, especially when explaining recursion of execution and recursive datatypes using basis and induction cases.It's a book for those who are interested in the crossover between CS theory and mathematics, but only introductory calculus is necessary (and that's only in one section).If you come from a procedural programming background, as I did, this book is an excellent introduction to the techniques of functional programming. I would recommend reading this in conjunction with ML for the Working Programmer by Paulson.If you are looking for a gentler introduction to functional languages, like LISP and its sister Scheme, try The Little Schemer by Friedman and Felleisen.

A decent overview of ML
While I find functional programming, and ML/SML in particular to be most annoying, this particular book is helpful in illuminating some key concepts of the paradigm.However, there are certainly sections where complex concepts are either glossed over, or explained in a very confusing manner (take Section 5.3.1, for example, which attempts, in a somewhat confusing manner, the limitations of polymorphic functionality in ML and it's relationship to types.A dense topic to be sure, but also poorly explained.)Additionally, there are some technical errors to be found in the book (eg: things that 'dont work' which really do, incorrect error messages, etc), which I mostly attribute to SML having been updated since the author published the book (not really his fault).

Certain things, ARE however, the author's fault.In particular, he addresses the audience with needlessly confusing 'Basis'/'Induction' definitions for many many things.For example, a binary tree is defined in such a way.This can be incredibly confusing, espcially if one does not already understand the concept of a BT or a BST. While ML/SML is a mathematical language, the author assumes too much formalism in his definitions, enough that the reading feels like reading a thick algorithms book at times (not a pleasant experience).Suggestion to author:Explain things simply instead of trying to coerce definitions into formalisms in which they do not belong (in particular the induction formalism which is very often confusing, use induction only when TRULY needed).

On the whole, ok to learn from, but can be overly verbose in some areas (eg: the belabored explination of all the error messages) , yet unclear in others... (eg: the density of several sections).

Also, as a parting note, there is not too much assumed about the reader, however, it helps to have a broad general computer science knowledge (as well as basic math, eg: calculus) unless you pickup new side-concepts very quickly. For example, in one example, the author uses the trapezoidal approixmation as an illustration of higher order functions. This is well and good, assuming you know calculus.While he does 'explain' the ideas (eg: what a binary search tree IS) if you havent had it presented to you before, you're in too deep.

Important: This is a ACADEMIC book, this is not something to pick up and read, it is far too dry for that.If you're looking for a good learning book, look elsewhere. ... Read more

Product Description
Concurrent Programming ML (CML), included as part of the SML of New Jersey (SML/NJ) distribution, combines the best features of concurrent programming and functional programming. This practical, "how-to" book focuses on the use of concurrency to implement naturally concurrent applications. In addition to a tutorial introduction to programming in CML, the book presents three extended examples using CML for practical systems programming: a parallel software build system, a simple concurrent window manager, and an implementation of distributed tuple spaces. This book also illustrates advanced SML programming techniques, and includes a chapter on the implementation of concurrency using features provided by the SML/NJ system. It will be of interest to programmers, students, and professional researchers working in computer language development. ... Read more

Customer Reviews (2)

Very nice book
This book is really good. Everything is absolutely clear, and decisions related to the design of CML itself are explained, as well as how to use the language. Besides, Chapter 2 has the best short (<40 pages) introduction to basic concepts in concurrent programming that I have seen.

Buy this book!
This is a book on Concurrent ML by the man who invented it.With so little CML information available on the web, this book has been one of the best investments I've made in years.Reppy starts off with a review of concurrency theory and then illustrates programming in CML through big, real-world examples.Throughout the book, he explains the motivation behind his design decisions.You end up with a clear picture of concurrent programming in a functional language -- concurrent programming in a REAL language like ML ... ... Read more

Product Description
The new edition of this successful and established textbook retains its two original intentions of explaining how to program in the ML language, and teaching the fundamentals of functional programming. The major change is the early and prominent coverage of modules, which the author extensively uses throughout. In addition, Paulson has totally rewritten the first chapter to make the book more accessible to students who have no experience of programming languages. The author describes the main features of new Standard Library for the revised version of ML, and gives many new examples, e.g. polynomial arithmetic and new ways of treating priority queues. Finally he has completely updated the references. Dr. Paulson has extensive practical experience of ML, and has stressed its use as a tool for software engineering; the book contains many useful pieces of code, which are freely available (via Internet) from the author. He shows how to use lists, trees, higher-order functions and infinite data structures.He includes many illustrative and practical examples, covering sorting, matrix operations, and polynomial arithmetic. He describes efficient functional implementations of arrays, queues, and priority queues. Larger examples include a general top-down parser, a lambda-calculus reducer and a theorem prover. A chapter is devoted to formal reasoning about functional programs. The combination of careful explanation and practical advice will ensure that this textbook continues to be the preferred text for many courses on ML for students at all levels. ... Read more

Customer Reviews (6)

the best!!
A great book, by the creator of the theorem provers Cambridge LCF and Isabelle/HOL.

ML was a language created by Robin Milner who had the ingenious idea of building LCF in ML and using ML's type system to ensure that theorems proved in LCF will always be secure.

This book explains programming in ML with an emphasis on building theorem provers, covering topics like lambda calculus.

The last chapter explains the full implementation of a simple theorem prover similar to LCF.This is invaluable to those who'd like to understand LCF, HOL, Isabelle, HOL Light, etc.

The past into the future?
My interest in learning ML started with reading the writings of people like Paul Graham who extoll the virtues of functional programming.ML seemed like the most accessible language for someone coming from an imperative oop background (due to the absence of '(' ... ')' which permeate Lisp and Scheme).There is however a dearth of introductory material on the web and what is out there seems to offer a piece meal, fragmentary overview.So I picked up this book and was not disappointed.

Paulson does an excellent job of introducing ML concepts in a clear logical manner.This book is about a lot more than ML though.Paulson teaches functional programming in this book with ML as the vehicle.This is a great book for self study.So why not five stars?The typesetting is horrendous.This is not a pretty book.

I think pretty much everyone will admit that ML never gained a lot of traction (Ocaml a bit more than SML I believe).The main problem I see with using ML for a large project is the lack of library support.So why learn ML?It turns out that ML has had an influence on new languages that have come out in recent years; F# and Scala are two.So time spent with ML should pay off when exploring these newer languages and whose close association with the .Net and Java platforms (respectively) cures the library availability dilemma.

Very Worthwhile
If you are looking for a book that will help extend your professional qualifications this is not it. However if work through this book you will emerge with much stronger programming skills in any programming language and gain some important insights in to writing intelligent programs.

The book teaches Standard ML.Standard ML is a clean, modern, strongly typed, functional programming language.Some SML compilers generate code that ranks among the best for higher level languages.Standard ML comes out of a community that has been interested in developing logical theorem provers and tools for formal analysis of programs.Don't let this scare you away -- any reasonably bright programmer should be able to follow Paulson's explanations.

The book provides an accessible introduction to programming with recursive functions, higher order functions (functions that process functions) and working with a language with polymorphic types (a little like C++'s templates but the compiler figures out the types).This is as much a book on algorithms and data structures from a functional point of view as it is a book on Standard ML.

I especially like the book's development of more advanced examples in the last two chapters. These have to do with writing programs that implement some key ideas in logic and computability theory.These were easy to follow even for a non-expert.I have a strong interest in how programs can be made to reason and learn and so these were really interesting.

Completely mistitled
This book is not bad; the explanation of all that it does explain is very good. It's just somewhat impractical, especially given the name; the title is a terrible misnomer for a book whose major example projects involve a lambda calculus evaluator and a proof assistant for first-order logic (not exactly the sort of thing "working" programmers usually have to do!).It does have some pretty solid demonstrations of how to implement various useful data structures and algorithms in SML (e.g. trees), but no "real-world" projects.

The problem with this book is typical of the problem facing a lot of introductory material for many of the more academic languages-- they explain the theory behind the language very well and how the features work, but they don't really teach you how to organize programs in the language, stuff like what code to put in what file, when to use modules and functors, etc. If you cut your teeth in imperative OOP like I did, reading this book you might get to understand the features of this language, but without still being clear about how one would go about writing an actual program in it.

Still, this is a book worth owning.

a good book, but it wasn't compelling for me
I have no doubt this is a well-written book (I read it in its entirety).Unfortunately, the examples weren't compelling to me at all.While the lambda calculus interpreter was interesting, the time spent on the theorem prover was not very interesting (I wonder if it was added as an homage to ML's legacy??).

Overall, I suppose this book is a little dated. ... Read more

Product Description
Introduction to Programming using SML provides a thorough introduction to the principles of programming and program design using the Standard ML programming language. The emphasis throughout is to p of programming into practice. The examples and exercises teach the student how to apply basic theoretical concepts to produce succinct and elegant programs and program designs.Coverage includes an introduction to fundamental data structures and their applications. The notions of binding, environment, store, closure and evaluation are introduced in order to explain the meaning of programs in an informal but precise way. Thus, the authors provide the reader with a set of durable programming concepts which will exist well into the next generation of programming languages. Features of the book include:Attractive and reader-friendly presentationClear and careful explanationsA rich collection of programming problems and a wide variety of

examplesCoverage of modelling and abstraction using data structures and the SML module systemOverview and statement of objectives at the start of each chapterAn introduction to producing technical documentation based on the SML module systemExtensive material in the appendices covering the SML language and

module system and selected parts of the SML basis libraryAccompanying Web Site supporting the book, containing all the program code, further teaching material and links to SML systems and other useful resources ... Read more

Customer Reviews (4)

Good introduction to functional programming
The book gives very good introduction to sml and functional programming. It is very easy to read (actually the first programming book I ever read), and it is very thorough. Beside teaching you sml the book gives examples of how to design, implement and write technical documentation for different problems.

The examples is carefully choosen to illustrate the power of sml.

All around a good book. Maybe it lacks a little more thorough explanation about higher order functions. But surely the best introductionary book about sml, I have ever read.

Gives a good foundation of functional programming
This book gives you a good foundation of functional programming, with many threads into more advanced topics.
The book also contains four chapters on problem solving, they will give you many ideas for practical use of the methods described.
The exampels contain insight in algoritms and datastructurs, and the use of ML types is presented with full understanding of the problems.
The book has a very compact structur, but gives good explanations on topics like recursive- and higher-order functions, datatypes and records.

For the campus bookstore only
This book is not very good as a general introduction to programming. This book wants to give you a tool which you can use to solve purely technical tasks. Further, it wants to give you a programming style before introducing any basic concepts about the programming language. Finally, SML is a bad choise if you are a complete newbie, as the SML lives in a very small world. There are 100s of books on other languages, but so far we only have 3 (three) books on SML. Because SML is a technical book for the university. However, I doubt anyone would buy this book if he or she was not a student. Besides, there are many errors in this book ... If you want an introduction to genuine programming, i suggest you read Teach Yourself C by Herbert Schildt.

Introduction to Programming using SML
This book is the best one you can read it on the subjsct of software engineering. It is highly organized and very accurat, you can depend on it to find your way in the world of programming. Also the price is not soexpensive so that any student in this field can by it. ... Read more

Product Description
This new, expanded textbook describes all phases of a modern compiler: lexical analysis, parsing, abstract syntax, semantic actions, intermediate representations, instruction selection via tree matching, dataflow analysis, graph-coloring register allocation, and runtime systems. It includes good coverage of current techniques in code generation and register allocation, as well as functional and object-oriented languages, that are missing from most books. In addition, more advanced chapters are now included so that it can be used as the basis for two-semester or graduate course. The most accepted and successful techniques are described in a concise way, rather than as an exhaustive catalog of every possible variant. Detailed descriptions of the interfaces between modules of a compiler are illustrated with actual C header files. The first part of the book, Fundamentals of Compilation, is suitable for a one-semester first course in compiler design. The second part, Advanced Topics, which includes the advanced chapters, covers the compilation ofobject-oriented and functional languages, garbage collection, loop optimizations, SSA form, loop scheduling, and optimization for cache-memory hierarchies. ... Read more

Customer Reviews (11)

Good coverage, decent depth, doesn't fully go to the depth of "functionality"
This book merits four stars: it covers lots of relevent subjects and tackles them to a good depth.
The book is about writing the compiler in ML. That's where I feel the book fails to shine: the design stays shallow. Arguably, high abstraction would have been hard to write about.

excellent book for introduction to compiler implementation
The book is very clear, well written and the author guides the reader with simplicity through all the steps required to implement a compiler. The code in ML to implement the most important routines is given with complete explanations.

For the other side the writing style is not enlightening, I did not fall in love of this book, but it is an excellent book for learning and understand.

Extremely valuable, but not for the faint of heart
I love this book.Having experimented with compiler construction for some time (though never seriously), and being a long-time ML user, Modern Compiler Implementation in ML was the perfect companion to my compiler-construction project.I largely ignored the "Tiger" language described in the book - I had my own ideas about what I wanted to create.Relying on the book to give you code for a whole compiler is asking far too much.The general concepts are explained, and then reinforced with sample code.I suspect the people who have complained bitterly about this book are actually just looking for a source code print out.

All in all, very worthwhile.Read a chapter, try to implement the concepts, and then either re-read the same chapter, or move on.

One of the better compiler texts
This book covers a remarkably broad territory of compiler issues, with a good balance of clarity and depth. It spends long enough on each topic to work through examples of functioning code, but doesn't dwell on any for so long that the reader loses interest. A decent set of variations on language design, runtime organization, and machine architecture are also discussed and implemented.

An important caveat is that readers ought to know some dialect of ML. If not, this book does not teach it; there are alternative renditions of the same text in C and Java, but I have not read them. Apparently many reviewers find those confusing. The java rendition, for example, has many angry reviewers. Possibly disgruntled students who had a hard time with their coursework, possibly people with valid complaints about the text.

All I can say is that I quite enjoyed it, and return to it regularly for its clear presentation, when working with related algorithms.

Good Information Masked by Bad Editting
This book has a lot of valuable information with regard to the construction of a compiler, that fact is overshadowed by the amazingly poor editting.

This is supposedly the "first edition reprint with corrections", but it seems like the vast majority of errors are yet to be corrected. ... Read more

Product Description
Both functional and concurrent programming are relatively new paradigms with great promise. In this book, a survey is provided of extensions to Standard ML, one of the most widely used functional languages, with new primitives for concurrent programming. Computer scientists and graduate students will find this a valuable guide to this topic. ... Read more

Product Description
An introduction to a functional programming subset of Standard ML. The emphasis of this book is on informal derivation of examples that show both correct and incorrect approaches. It shows functional language as a practical tool for software design and contains real life examples to allow for large scale software engineering issues. ... Read more

Product Description
The functional programming language ML is becoming the main medium for teaching functional ideas in a university environment. This book is introductory and adopts an incremental approach, whilst the coverage is problem-oriented: at each stage a problem is introduced which can be solved by the techniques the book teaches. Beginning with a historical perspective and an introduction to simple functions, the book goes on to cover areas such as recursive functions, dynamic types and higher order functions. A real-life case study is included. ... Read more

Product Description
Standard ML is a general-purpose programming language designed for large projects. This book provides a formal definition of Standard ML for the benefit of all concerned with the language, including users and implementers. Because computer programs are increasingly required to withstand rigorous analysis, it is all the more important that the language in which they are written be defined with full rigor.One purpose of a language definition is to establish a theory of meanings upon which the understanding of particular programs may rest. To properly define a programming language, it is necessary to use some form of notation other than a programming language. Given a concern for rigor, mathematical notation is an obvious choice. The authors have defined their semantic objects in mathematical notation that is completely independent of Standard ML.In defining a language one must also define the rules of evaluation precisely--that is, define what meaning results from evaluating any phrase of the language. The definition thus constitutes a formal specification for an implementation. The authors have developed enough of their theory to give sense to their rules of evaluation.The Definition of Standard ML is the essential point of reference for Standard ML. Since its publication in 1990, the implementation technology of the language has advanced enormously and the number of users has grown. The revised edition includes a number of new features, omits little-used features, and corrects mistakes of definition. ... Read more

Customer Reviews (3)

How language definitions should be done
This book is a lesson to programming languages everywhere.The language definition is succinct, accurate, and to the point.Anyone who has attempted to penetrate such documents as the ANSI C or C++ standard is met with hundreds of pages of ambiguous, confusing language, about which formal reasoning is next to impossible.By contrast, this book describes the language syntax and semantics in a precise, mathematical style, making actual implementation of the language straightforward, as well as providing a usable definition for reasoning about the correctness of implementations.This is an example of how language definitions should be done.

Cryptic
This book was apparently written by Math PHDs for use by Math PHDs.I found it to be pretty impenetrable.With this sort of language report, and the shortage of "how to" books for beginners, SML is probably doomed to obscurity, which is unfortunate.

BECOME the language!
To explain it in the words of the authors: "The keystone of the method [used to define Standard ML in this book], then, is a certain kind of assertion that takes the form B |- P => M and may be pronounced: 'Against the background B, the phrase P evaluates to the meaning M.'Theformal purpose of this Definition is no more, and no less, than to decreeexactly which assertions of this form are true."

Standard ML is avery powerful language because of the abilities it grants and therestrictions it enforces.While reading this book will not teach you SML,it will help reinforce its subtle elegance.If you have developed aninfatuation with this language, you will not be able to resist the onlybook that truly contains it.

While not necessary to enjoy this volume, aprerequisite to have any understanding of its contents is some sort ofbackground in type theory and mathematical logic that a course like thisone taught by Harper... can only beginto provide.

And remember, ML loves you! ... Read more

Product Description
SML is an influential programming language that represents many state-of-the-art aspects of language design in a form usable for everyday programming.The language is in use worldwide, with applications ranging from network communication to theorem proving. The definition for SML's standard library, this work concisely describes the types and functions defined in the library and discusses in depth the library's design and use. This manual will be an indispensable reference for students, professional programmers, and language designers. ... Read more

Product Description
Dieses Lehrbuch gibt eine kompakte Einführung in die Konzepte, Methoden und Techniken der funktionalen oder applikativen Programmierung. Es setzt keine Programmierkenntnisse voraus und eignet sich damit insbesondere für Anfänger, aber auch für alle, die mit der imperativen Programmierung vertraut sind und sich in die Thematik einarbeiten möchten. Mathematisch fundiert werden die theoretischen Grundlagen der Programmierung und ihre praktische Umsetzung behandelt. Das Ziel dabei ist, auch große Systeme entwerfen und handhaben zu können. Am Beispiel der modernen Programmiersprachen Opal, ML, Haskell und Gofer werden sowohl elementare als auch weiterführende Aspekte vorgestellt. Im Vordergrund stehen dabei immer konzeptuelle Fragestellungen und nicht vollständige Sprachbeschreibungen. ... Read more

Product Description
Chapters: Ml, Standard Ml, Objective Caml, Mythryl, F Sharp, Nemerle, Alice, Standard Ml of New Jersey, Concurrent Ml, Rpal, Extended Ml, Extensible Ml, Lazy Ml, Mlton, Jocaml, Macroml, Dependent Ml, Moscow Ml. Source: Wikipedia. Pages: 99. Not illustrated. Free updates online. Purchase includes a free trial membership in the publisher's book club where you can select from more than a million books without charge. Excerpt: Standard ML (SML) is a general-purpose, modular, functional programming language with compile-time type checking and type inference. It is popular among compiler writers and programming language researchers, as well as in the development of theorem provers. SML is a modern descendant of the ML programming language used in the Logic for Computable Functions (LCF) theorem-proving project. It is distinctive among widely used languages in that it has a formal specification, given as typing rules and operational semantics in The Definition of Standard ML (1990, revised and simplified as The Definition of Standard ML (Revised) in 1997). Standard ML is a functional programming language with some impure features. Programs written in Standard ML consist of expressions to be evaluated, as opposed to statements or commands, although some expressions return a trivial "unit" value and are only evaluated for their side-effects. Like all functional programming languages, a key feature of Standard ML is the function, which is used for abstraction. For instance, the factorial function can be expressed as: fun factorial n = if n = 0 then 1 else n * factorial (n-1)A Standard ML compiler is required to infer the static type int - ... Read more

Product Description
The full mathematical description of the functional programming language ML was given in Milner, Tofte, and Harper's Definition of Standard ML. This companion volume explains in depth the meaning, or semantic theory, of ML. Together, the two volumes provide a complete understanding of the most prominent of a new group of functional programming languages that includes Haskell and Scheme.

In making the Definition easier to understand, the authors not only explain what ML is, they explain why it is. They present some of the rigorous analysis that supports the Definition including a selection of theorems that express important properties of the language. The Commentary is also a working document that shows the way in which the specialized theory of ML can contribute to broader research on language design and semantics.

Contents: Preface. Executing a Simple Program. Dynamic Semantics for the Core. Dynamic Semantics for the Modules. Static Semantics for the Core. Type Declarations and Principality. Static Semantics for the Modules. Signature Matching. Elaboration of Functors. Admissible Semantic Objects and Proofs. Elaboration of Signature Expressions. Principal Signatures. Appendixes: Proof of Principality. Identifier Status. Solutions to Exercises. Mistakes and Ambiguities. ... Read more

Product Description
Ryan Stansifer introduces the first concise, user-oriented introduction to the newly emerging programming language, Standard ML. The discussion is kept simple and augmented with copious example to help introduce users to this strongly typed, functional language. The text is ideal as a basic introduction to ML or as a supplement for a comparative languages course. ... Read more

Customer Reviews (1)

Excellent tutorial to the ML; great for beginners!

This primer is a fun and gentle read. An excellent tutorial for ML beginners. Highly recommended to people who are interested in learning more about the ML language and basic concepts in functional programming.

The author has a clear grasp and good understanding of his intended audience. His prose style is highly engaging.

I simply couldn't put the book down until I finished reading it. Yes, it's that fun! One of the best introductory programming language books around, on par with the "Little Lisper"!! It sure would make you want to learn more about functional programming in general.

This is a great textbook for undergrad computer science introductory programming courses. I know most students would appreciate it if there are more introductory books like this in computer science.

Lee ... Read more

Product Description
With the increasing capacities of today's computers, high order programming has gradually gained ground, not only in academic research but also in industrial applications as a specification and prototyping tool. On the other hand, the interest in functional programming has created new fields of academic research. Although this research is directly motivated by problems arising when implementing functional languages or designing functional programmes, its actual relation to "everyday programming" is often overlooked. The main aim of this book is to bring together theory and practice and to illustrate both the gains and the difficulties that a programmer may face. The book assumes that the reader has some programming practice, in particular with functional programming. Evolved from lecture notes for students, it also includes exercises. ... Read more

Product Description

This tutorial book presents seven carefully revised lectures given at the 6th International School on Functional Programming, AFP 2008, in Heijen, The Netherlands in May 2008.

The book presents the following seven, carefully cross-reviewed chapters, written by leading authorities in the field: Self-adjusting: Computation with Delta ML, spider spinning for dummies, from reduction-based to reduction-free normalization, libraries for generic programming in Haskell, dependently typed programming in agda, parallel and concurrent programming in Haskell and an iTask case study: a conference management system.

Product Description
High Quality Content by WIKIPEDIA articles! In computer science, a tagged union, also called a variant, variant record, discriminated union, or disjoint union, is a data structure used to hold a value that could take on several different, but fixed types. Only one of the types can be in use at any one time, and a tag field explicitly indicates which one is in use. It can be thought of as a type which has several "cases," each of which should be handled correctly when that type is manipulated. Like ordinary unions, tagged unions can save storage by overlapping storage areas for each type, since only one is in use at a time. Tagged unions are most important in functional languages such as ML and Haskell, where they are called datatypes (see algebraic data type) and the compiler is able to verify that all cases of a tagged union are always handled, avoiding many types of errors. They can, however, be constructed in nearly any language, and are much safer than untagged unions, often simply called unions, which are similar but do not explicitly keep track of which member of the union is currently in use. ... Read more