Books

Books covering many aspects of Haskell.

Language and library definition

Simon Peyton Jones: "Haskell 98 language and libraries: the Revised Report", Cambridge University Press, 2003, Hardback, 272 pages, ISBN 0521826144, £45.00

Book Description
Haskell is the world's leading lazy functional programming language, widely used for teaching, research, and applications. The language continues to develop rapidly, but in 1998 the community decided to capture a stable snapshot of the language: Haskell 98. All Haskell compilers support Haskell 98, so practitioners and educators alike have a stable base for their work. This book constitutes the agreed definition of the Haskell 98, both the language itself and its supporting libraries. It has been considerably revised and refined since the original definition, and appears in print for the first time. It should be a standard reference work for anyone involved in research, teaching, or application of Haskell. The entire language definition is also available online: Language and library specification.

Textbooks

Alejandro Serrano Mena: Beginning Haskell, Paperback / eBook: 498 pages, Apress (January 2014), English, ISBN: 978-1-43026-250-3

Book Description
Beginning Haskell provides a broad-based introduction to the Haskell language, its libraries and environment, and to the functional programming paradigm that is fast growing in importance in the software industry. The book takes a project-based approach to learning the language that is unified around the building of a web-based storefront. Excellent coverage is given to the Haskell ecosystem and supporting tools. These include the Cabal build tool for managing projects and modules, the HUnit and QuickCheck tools for software testing, the Scotty framework for developing web applications, Persistent and Esqueleto for database access, and also parallel and distributed programming libraries.

Miran Lipovača: Learn You a Haskell for Great Good!, Paperback: 360 pages, No Starch Press (April 2011), English, ISBN: 978-1-59327-283-8

Book Description
It's all in the name: Learn You a Haskell for Great Good! is a hilarious, illustrated guide to this complex functional language. Packed with the author's original artwork, pop culture references, and most importantly, useful example code, this book teaches functional fundamentals in a way you never thought possible.

Graham Hutton: Programming in Haskell, Paperback: 200 pages, Cambridge University Press (January 31, 2007), English, ISBN 0521692695

Book Description
Haskell is one of the leading languages for teaching functional programming, enabling students to write simpler and cleaner code, and to learn how to structure and reason about programs. This introduction is ideal for beginners: it requires no previous programming experience and all concepts are explained from first principles via carefully chosen examples. Each chapter includes exercises that range from the straightforward to extended projects, plus suggestions for further reading on more advanced topics. The author is a leading Haskell researcher and instructor, well-known for his teaching skills. The presentation is clear and simple, and benefits from having been refined and class-tested over several years. The result is a text that can be used with courses, or for self-learning. Features include: freely accessible Powerpoint slides for each chapter; solutions to exercises, and examination questions (with solutions) available to instructors; downloadable code that's fully compliant with the latest Haskell release.

Bryan O'Sullivan, Don Stewart, and John Goerzen: Real World Haskell, Paperback: 700 pages, O'Reilly, November 2008, English, ISBN-10: 0596514980, ISBN-13: 978-0596514983

See Real World Haskell.

Simon Marlow: Parallel and Concurrent Programming in Haskell, Paperback: 322 pages, O'Reilly, August 2013, English, ISBN-10: 1449335942, ISBN-13: 978-1449335946

Book Description
f you have a working knowledge of Haskell, this hands-on book shows you how to use the language’s many APIs and frameworks for writing both parallel and concurrent programs. You’ll learn how parallelism exploits multicore processors to speed up computation-heavy programs, and how concurrency enables you to write programs with threads for multiple interactions. Author Simon Marlow walks you through the process with lots of code examples that you can run, experiment with, and extend. Divided into separate sections on Parallel and Concurrent Haskell, this book also includes exercises to help you become familiar with the concepts presented:

• Express parallelism in Haskell with the Eval monad and Evaluation Strategies
• Parallelize ordinary Haskell code with the Par monad
• Build parallel array-based computations, using the Repa library
• Use the Accelerate library to run computations directly on the GPU
• Work with basic interfaces for writing concurrent code
• Build trees of threads for larger and more complex programs
• Learn how to build high-speed concurrent network servers
• Write distributed programs that run on multiple machines in a network

Nishant Shukla: Haskell Data Analysis Cookbook, Paperback: 334 pages, Packt, June 2014, English, ISBN-10: 1783286334, ISBN-13: 978-1783286331

Book Description
This book will take you on a voyage through all the steps involved in data analysis. It provides synergy between Haskell and data modeling, consisting of carefully chosen examples featuring some of the most popular machine learning techniques. You will begin with how to obtain and clean data from various sources. You will then learn how to use various data structures such as trees and graphs. The meat of data analysis occurs in the topics involving statistical techniques, parallelism, concurrency, and machine learning algorithms, along with various examples of visualizing and exporting results. By the end of the book, you will be empowered with techniques to maximize your potential when using Haskell for data analysis. The GitHub public repository contains over 130 practical recipes to accompany every chapter of the book. Use it as a Swiss Army Knife of algorithms and code snippets. Try a recipe a day, like a kata for your mind.

Paul Hudak: The Haskell School of Expression: Learning Functional Programming through Multimedia, Cambridge University Press, New York, 2000, 416pp, 15 line diagrams, 75 exercises, Paperback $29.95, ISBN 0521644089, Hardback $74.95, ISBN 0521643384

Book Description
This book teaches functional programming as a way of thinking and problem solving, using Haskell, the most popular purely functional language. Rather than using the conventional mathematical examples commonly found in other programming language textbooks, the author draws examples from multimedia applications, including graphics, animation, and computer music, thus rewarding the reader with working programs for inherently more interesting applications. Aimed at both beginning and advanced programmers, this tutorial begins with a gentle introduction to functional programming and moves rapidly on to more advanced topics. An underlying theme is the design and implementation of domain specific languages, using three examples: FAL (a Functional Animation Language), IRL (an Imperative Robot Language), and MDL (a Music Description Language). Details about programming in Haskell are presented in boxes throughout the text so they can be easily referred to and found quickly. The book's Web Site contains source files for all programs in the text, as well as the graphics libraries to run them under Windows and Linux platforms. It also contains PowerPoint slides useful for teaching a course using the textbook.

• There is a review of SOE on this wiki: The Monad.Reader/Issue3/SoE Review.

Simon Thompson: Haskell: The Craft of Functional Programming, Second Edition, Addison-Wesley, 507 pages, paperback, 1999. ISBN 0-201-34275-8.

Book Description
The second edition of Haskell: The Craft of Functional Programming is essential reading for beginners to functional programming and newcomers to the Haskell programming language. The emphasis is on the process of crafting programs and the text contains many examples and running case studies, as well as advice an program design, testing, problem solving and how to avoid common pitfalls. Building on the strengths of the first edition, the book includes many new and improved features:

• Complete coverage of Haskell 98, the standard version of Haskell which will be stable and supported by implementations for years to come.
• An emphasis on software engineering principles, encouraging a disciplined approach to building reusable libraries of software components.
• Detailed coverage of the Hugs interpreter with an appendix covering other implementations.
• A running case study of pictures emphasizes the built-in functions which appear in the standard prelude and libraries. It is also used to give an early preview of some of the more complex language features, such as high-order functions.
• List comprehensions and the standard functions over lists are covered before recursion.
• Early coverage of polymorphism supporting the "toolkit" approach and encouraging the resuse of built-in functions and types.
• Extensive reference material containing details of further reading in books, journals and on the World Wide Web.
• Accompanying Web Site supporting the book, containing all the program code, further teaching materials and other useful resources.

Synopsis
This books introduces Haskell at a level appropriate for those with little or no prior experience of functional programming. The emphasis is on the process of crafting programs, solving problems, and avoiding common errors.

Richard Bird: Introduction to Functional Programming using Haskell, 2nd edition, Prentice Hall Press, 1998, 460 pp., ISBN 0-13-484346-0.

From the cover: After the success of the first edition, Introduction to Functional Programming using Haskell has been thoroughly updated and revised to provide a complete grounding in the principles and techniques of programming with functions. The second edition uses the popular language Haskell to express functional programs. There are new chapters on program optimisation, abstract datatypes in a functional setting, and programming in a monadic style. There are completely new case studies, and many new exercises. As in the first edition, there is an emphasis on the fundamental techniques for reasoning about functional programs, and for deriving them systematically from their specifications. The book is self-contained, assuming no prior knowledge of programming, and is suitable as an introductory undergraduate text for first- or second-year students.

Antony Davie: An Introduction to Functional Programming Systems Using Haskell, Cambridge University Press, 1992. ISBN 0-521-25830-8 (hardback). ISBN 0-521-27724-8 (paperback).

Cover: Functional programming is a style of programming that has become increasingly popular during the past few years. Applicative programs have the advantage of being almost immediately expressible as functional descriptions; they can be proved correct and transformed through the referential transparency property. This book presents the basic concepts of functional programming, using the language Haskell for examples. The author incorporates a discussion of lambda calculus and its relationship with Haskell, exploring the implications for raparallelism. Contents: SASL for Beginners / Examples of SASL Programming / More Advanced Applicative Programming Techniques / Lambda Calculus / The Relationship Between Lambda Calculus and SASL / Program Transformation and Efficiency / Correctness, Equivalence and Program Verification / Landin's SECD Machine and Related Implementations / Further Implementation Techniques / Special Purpose Hardware / The Applicative Style of Semantics / Other Applicative Languages / Implications for Parallelism / Functional Programming in Von Neumann Languages

Fethi Rabhi and Guy Lapalme: Algorithms: A functional programming approach,

Addison-Wesley, 235 pages, paperback, 1999. ISBN 0-201-59604-0

Book Description
The authors challenge more traditional methods of teaching algorithms by using a functional programming context, with Haskell as an implementation language. This leads to smaller, clearer and more elegant programs which enable the programmer to understand the algorithm more quickly and to use that understanding to explore alternative solutions.
Key features:

• Most chapters are self-contained and can be taught independently from each other.
• All programs are in Haskell'98 and provided on a WWW site.
• End of chapter exercises throughout.
• Comprehensive index and bibliographical notes.

Synopsis
The book is organised as a classic algorithms book according to topics such as Abstract Data Types, sorting and searching. It uses a succession of practical programming examples to develop in the reader problem-solving skills which can be easily transferred to other language paradigms. It also introduces the idea of capturing algorithmic design strategies (e.g. Divide-and-Conquer, Dynamic Programming) through higher-order functions.
Target audience
The book is intended for computer science students taking algorithms and/or (basic or advanced) functional programming courses.

Jeremy Gibbons and Oege de Moor (eds.): The Fun of Programming,Palgrave, 2002, 288 pages. ISBN 0333992857.

Book description:
In this textbook, leading researchers give tutorial expositions on the current state of the art of functional programming. The text is suitable for an undergraduate course immediately following an introduction to functional programming, and also for self-study. All new concepts are illustrated by plentiful examples, as well as exercises. A website gives access to accompanying software.

Simon Peyton Jones: Implementation of Functional Programming Language], 500 pages, Prentice-Hall, 1987. ISBN 0134533259.

This 1987 book is now out of print, but it is now available online in its entirety.

Simon Peyton Jones, David Lester: Implementing Functional Languages, Paperback: 288 pages, Prentice Hall (August 1992), English, ISBN 0137219520

The book is out of print. The full sources and a postscript version are available for free. This book gives a practical approach to understanding the implementations of non-strict functional languages using lazy graph reduction. The emphasis of the book is on building working prototypes of several functional language implementations (template- instantiation, G-Machine, TIM, parallel G-Machine. In each case the authors provide a complete working prototype of a particular implementation, and then lead the reader through a sequence of improvements which expand its scope. This enables readers to develop, modify and experiment with their own implementations and for use as a source of practical laboratory work material.

Simon Thompson: Type Theory and Functional Programming, Addison-Wesley, 1991. ISBN 0-201-41667-0. Hardcover: 388 pages.

Now out of print, the original version is available here. Preface: Constructive Type theory has been a topic of research interest to computer scientists, mathematicians, logicians and philosophers for a number of years. For computer scientists it provides a framework which brings together logic and programming languages in a most elegant and fertile way: program development and verification can proceed within a single system. Viewed in a different way, type theory is a functional programming language with some novel features, such as the totality of all its functions, its expressive type system allowing functions whose result type depends upon the value of its input, and sophisticated modules and abstract types whose interfaces can contain logical assertions as well as signature information. A third point of view emphasizes that programs (or functions) can be extracted from proofs in the logic.

Claudio Cesar de Sá and Marcio Ferreira da Silva: Haskell: Uma Abordagem Prática, Novatec Editora Ltda., 2006, 296 pages, ISBN 85-7522-095-0. The price is R$ 62,00 (in Reais). Language: Portuguese

This book is being published by Novatec Editora Ltda. You can access directly here.
Book description:
This book brings a comprehensive vision of Haskell language. No knowledge in another functional programming language is expected. In addition, no background in programming is required. The book presents issues from basic up to an intermediate level; it also includes some advanced aspects of Haskell. The title of the book, Haskell: Uma Abordagem Prática, in English Haskell: A Practical Approach, is the essence of the book. The result is a text that can be used in courses of programming and paradigms languages. Finally, many practical examples can be found throughout the book. An additional page containing comments on this book is found here: [1]. Other data as bibtex entry, cover's book in several formats, Winhugs-2001 for download, and so on. This page is Portuguese.

Blas C. Ruiz, Francisco Gutiérrez, Pablo Guerrero y José E. Gallardo. Razonando con Haskell, Thompson 2004. ISBN 84-9732-277-0. Language: Spanish

Descripción El objetivo principal de este libro es el de servir como libro de texto de las asignaturas de Programación Declarativa correspondientes a los estudios de Informática o Ciencias de la Computación, y otras ciencias en general ( Matemáticas, Física, etc.). El texto es fruto de una larga experiencia docente de los autores dentro de las distintas asignaturas que desarrollan la Programación Funcional en distintas titulaciones de la Universidad de Málaga. Aún así, su lectura no queda condicionada a un conocimiento previo sobre lenguajes de programación (de computadores), ni sobre Informática. De esta forma, el libro puede ser utilizado por todo aquel que desee tener un conocimiento amplio sobre la Programación Funcional.

Haskell Primer: The first functional language to learn. Jun Mukai. In Japanese. Yen 2,730.

Practical Haskell Programming, Minero Aoki and Nobuo Yamashita. A primer on functional programming for real world programs. In Japanese. Yen 2,940.

Purely Functional Data Structures Chris Okasaki, 232 pp., Cambridge University Press, 1998. ISBN 0-521-63124-6

From the cover:
Most books on data structures assume an imperative language like C or C++. However, data structures for these languages do not always translate well to functional languages such as Standard ML, Haskell, or Scheme. This book describes data structures and data structure design techniques from the point of view of functional languages. It includes code for a wide assortment both of classical data structures and of data structures developed exclusively for functional languages.This handy reference for professional programmers working with functional languages can also be used as a tutorial or for self-study. Haskell source code for the book

Функциональное программирование на языке Haskell

Справочник по языку Haskell

Практика работы на языке Haskell

14 занимательных эссе о языке Haskell и функциональном программировании

Introducere in Haskell 98 prin exemple : Dan Popa, 230 pp., Edusoft Bacau, Romania, (Ian, 31, 2007),Romanian, ISBN 978-973-8934-48-1

De pe coperta
(ro) Cartea este simultan un manual introductiv de Haskell si o carte auxiliara pentru studentii de la cursul de limbaje formale. Veti avea satisfactia cunoasterii unui limbaj modern (...) in care algoritmul de sortare Quicksort se scrie pe 6 randuri, asa cum se poate vedea de altfel si in imaginea de pe coperta I. (...) Cartea cuprinde o serie de capitole folosite la Universitatea Bacau in calitate de auxiliare de laborator la disciplina Limbaje Formale si Automate.
(en) This book is simultaneosly a manual of Haskell and an auxiliary book for the students of the FLA course (Formal Languges and Automata). You will be satisfied by this modern language,Haskell. Why ? Using Haskell the Quicksort algorithm can be writen on 6 lines (or less), as you can see on the cover. And that's not all ... This book is used at Bacau State University, Romania.

James Church :

Advanced Data Analysis with Haskell Video, ISBN13 9781785287237, Course Length 4 hours 4 minutes Packt, December 2016

Video Description
In this video, you will be guided on how to find correlations in data, as well as multiple dependent variables. You will be given a theoretical overview of the types of regression and we’ll show you how to install the LAPACK and HMatrix libraries. By the end of the first part, you’ll be familiar with the application of N-grams and TF-IDF. Once you’ve learned how to analyze data, the next step is organizing that data with the help of machine learning algorithms. You will be briefed on the mathematics and statistical theorems such as Baye’s law and its application, as well as eigenvalues and eigenvectors using HMatrix. By the end of this course, you’ll have an understanding of data analysis, different ways to analyze data, and the various clustering algorithms available. You’ll also understand Haskell and will be ready to write code with it.

Hakim Cassimally :

Learning Haskell Programming Video, ISBN13 9781786465542, Course Length 4 hours 10 minutes Packt, December 2016

Video Description
This video would begin with the fundamentals and building blocks of Haskell programming language with special emphasis on functional programming. It will be covering how Haskell variables, syntax work alongwith Haskell datatypes and functions. You will learn how to solve programming problems while creating an application with hands-on experience. You will then move on to learning writing expressions and high-order functions. At the end of the video, you will be able to build a complete application with Haskell alongwith learning the important functionalities.

Samuli Thomasson:

Haskell High Performance Programming Book, ISBN 139781786464217, Paperback, 408 pages Packt, September 2016

Book Description
Haskell, with its power to optimize the code and its high performance, is a natural candidate for high performance programming. It is especially well suited to stacking abstractions high with a relatively low performance cost. This book addresses the challenges of writing efficient code with lazy evaluation and techniques often used to optimize the performance of Haskell programs. Learn to use parallelism and explore the concept of streaming. This book demonstrates the benefits of running multithreaded and concurrent applications. Next it will guide you through various profiling tools that will help you identify performance issues in your program.

James Church:

Getting Started with Haskell Data Analysis Video, Course Length: 3 hours 18 minutes, Packt, July 2016, English, ISBN-13: 9781785880841

Course Description
Data analysis is part computer science and part statistics. An important part of data analysis is validating your assumptions with real-world data to see if there is a pattern, or a particular user behavior that you can validate. This video course will help you get up to speed with the basics of data analysis and approaches in the Haskell language. You'll learn about statistical computing, file formats (CSV and SQLite3), descriptive statistics, charts, and onto more advanced concepts like understanding the importance of normal distribution. Whilst mathematics is a big part of data analysis, we’ve tried to keep this course simple and approachable so that you can apply what you learn to the real world.

Ryan Lemmer:

Haskell Design Patterns, Paperback: 166 pages, Packt, November 2015, English, ISBN-10: 1-783-98872-X, ISBN-13: 9781783988723

Book Description
Design patterns and idioms can widen our perspective by showing us where to look, what to look at, and ultimately how to see what we are looking at. At their best, patterns are a shorthand method of communicating better ways to code (writing less, more maintainable, and more efficient code). This book starts with Haskell 98 and through the lens of patterns and idioms investigates the key advances and programming styles that together make "modern Haskell". Your journey begins with the three pillars of Haskell. Then you'll experience the problem with Lazy I/O, together with a solution. You'll also trace the hierarchy formed by Functor, Applicative, Arrow, and Monad. Next you'll explore how Fold and Map are generalized by Foldable and Traversable, which in turn is unified in a broader context by functional Lenses. You'll delve more deeply into the Type system, which will prepare you for an overview of Generic programming. In conclusion you go to the edge of Haskell by investigating the Kind system and how this relates to Dependently-typed programming.

James Church:

Learning Haskell Data Analysis, Paperback: 198 pages, Packt, May 2015, English, ISBN-10: 1-784-39470-7, ISBN-13: 9781784394707

Book Description
This book provides you with the skills to handle large amounts of data, even if that data is in a less than perfect state. Each chapter in the book helps to build a small library of code that will be used to solve a problem for that chapter. The book starts with creating databases out of existing datasets, cleaning that data, and interacting with databases within Haskell in order to produce charts for publications. It then moves towards more theoretical concepts that are fundamental to introductory data analysis, but in a context of a real-world problem with real-world data. As you progress in the book, you will be relying on code from previous chapters in order to help create new solutions quickly. By the end of the book, you will be able to manipulate, find, and analyze large and small sets of data using your own Haskell libraries.

Foundations

Types and Programming Languages by Benjamin C. Pierce. 645 pages, The MIT Press, (February 1, 2002), English. ISBN 0262162091

From the cover:
A type system is a syntactic method for automatically checking the absence of certain erroneous behaviors by classifying program phrases according to the kinds of values they compute. The study of type systems--and of programming languages from a type-theoretic perspective-has important applications in software engineering, language design, high-performance compilers, and security. This text provides a comprehensive introduction both to type systems in computer science and to the basic theory of programming languages. The approach is pragmatic and operational; each new concept is motivated by programming examples and the more theoretical sections are driven by the needs of implementations. Each chapter is accompanied by numerous exercises and solutions, as well as a running implementation, available via the Web. Dependencies between chapters are explicitly identified, allowing readers to choose a variety of paths through the material. The core topics include the untyped lambda-calculus, simple type systems, type reconstruction, universal and existential polymorphism, subtyping, bounded quantification, recursive types, kinds, and type operators. Extended case studies develop a variety of approaches to modeling the features of object-oriented languages.

Advanced Topics in Types and Programming Languages by Benjamin C. Pierce (Editor), Hardcover: 608 pages, The MIT Press (December 23, 2004), Language: English, ISBN 0262162288.

From the cover:
The study of type systems for programming languages now touches many areas of computer science, from language design and implementation to software engineering, network security, databases, and analysis of concurrent and distributed systems. This book offers accessible introductions to key ideas in the field, with contributions by experts on each topic. The topics covered include precise type analyses, which extend simple type systems to give them a better grip on the run time behavior of systems; type systems for low-level languages; applications of types to reasoning about computer programs; type theory as a framework for the design of sophisticated module systems; and advanced techniques in ML-style type inference. Advanced Topics in Types and Programming Languages builds on Benjamin Pierce's Types and Programming Languages (MIT Press, 2002); most of the chapters should be accessible to readers familiar with basic notations and techniques of operational semantics and type systems -- the material covered in the first half of the earlier book. Advanced Topics in Types and Programming Languages can be used in the classroom and as a resource for professionals. Most chapters include exercises, ranging in difficulty from quick comprehension checks to challenging extensions, many with solutions.

Programming Languages: Theory and Practice by Robert Harper. (Draft).

A working draft of a planned book on the theoretical foundations of practical programming languages.

Computational Semantics and Type Theory by Jan van Eijck. Draft.

Text online.

Proofs and Types by Jean-Yves Girard translated and with appendices by Paul Taylor and Yves Lafont.

Based on a short graduate course on typed lambda-calculus given at the Universit Paris VII in the autumn term of 1986-7.

Programming language theory texts online

Collection of online programming language theory texts maintained by Frank Atanassow

Programming in Martin-Löf's Type Theory: An Introduction by Bengt Nordström, Kent Petersson and Jan M. Smith. 1990.

Monadic Programming

Practical monadic interpretation by Dan Popa , Language: Romanian

Foreword of the book (en): I am delighted to introduce this book on the use of monads in Haskell as a way of structuring interpreters. In the early days, Haskell's most distinctive feature was lazy evaluation. Laziness forced us to take a pure approach to input/output, which meant that Haskell's I/O was initially rather weak. This weakness ultimately proved a strength, however, because it led us to the discovery that monads were not just an abstract mathematical concept, but were immediately applicable as a powerful program structuring mechanism. Monadic programming is not just to do with input/output: it is much more powerful. That is why I am pleased to see this book, which describes in some detail how to write a language interpreter using a monadic approach. In retrospect, the discovery of monads as a practical programming pattern is one of Haskell's most substantial contributions to the world of programming -- and it is one that you will share if you work through this book. I am also very happy to see Haskell growing in popularity among our brothers and sisters in Eastern Europe, and in Romania in particular. Enjoy! Simon P.J.

Mathematics

See Books and tutorials/Mathematics

Miscellaneous

Real World #haskell

Joke

Team "Referential Transparent Sea Keepers": Functional Ikamusume

book series, Japanese

Book Description
Functional Ikamusume book series provides a forum for researchers, developers, and anime-watchers to publish their latest work, articles, and “mousou (妄想)” on the design, implementations, principles, and uses of functional programming and Ikamusume. The book series covers the entire spectrum of work, from practice to theory, from frank introduction of functional programming to latest research work, from Ikamusume with some functional flavor to functional programming with some Ikamusume flavor. Let’s enjoy writing articles on functional programming in frank “geso” style de-geso!! Past books are written entirely in Japanese, and books are planned to be sold in Japan, but we also accept articles in English. For more information on functional Ikamusume, see the links above (all in Japanese), or ask @xhl_kogitsune or "other members" on twitter, or xhlkogitsune on Skype. You don’t have to be worried about what is Functional Ikamusume —— she is just Ikamusume who loves functional programming, as you love it. If you are interested in writing Functional Ikamusume articles, please contact xhlkogitsune on Skype or the authors on twitter. You can use Japanese or English for discussion. A text chat room is on Skype, and I’ll invite you to the chat room. While the chat is currently in Japanese, most participants can read/write English.