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. Additional features include: freely available powerpoint slides, Haskell code and solutions to exercises.
History
Following the release of Miranda by Research Software Ltd, in 1985, interest in lazy functional languages grew.[citation needed] By 1987, more than a dozen non-strict, purely functional programming languages existed. Of these, Miranda was the most widely used, but was not in the public domain. At the conference on Functional Programming Languages and Computer Architecture (FPCA '87) in Portland, Oregon, a meeting was held during which participants formed a strong consensus that a committee should be formed to define an open standard for such languages. The committee's purpose was to consolidate the existing functional languages into a common one that would serve as a basis for future research in functional-language design.The first version of Haskell ("Haskell 1.0") was defined in 1990. The committee's efforts resulted in a series of language definitions. In late 1997, the series culminated in Haskell 98, intended to specify a stable, minimal, portable version of the language and an accompanying standard library for teaching, and as a base for future extensions. The committee expressly welcomed the creation of extensions and variants of Haskell 98 via adding and incorporating experimental features.
In February 1999, the Haskell 98 language standard was originally published as "The Haskell 98 Report". In January 2003, a revised version was published as "Haskell 98 Language and Libraries: The Revised Report".The language continues to evolve rapidly, with the GHC implementation representing the current de facto standard. In early 2006, the process of defining a successor to the Haskell 98 standard, informally named Haskell′ ("Haskell Prime"), was begun. This process is intended to produce a minor revision of Haskell 98,which has been named Haskell 2010.
Language features
Haskell is a large, complex language, with several standardised versions, and many non-standard extensions. It shares many features with imperative languages, and other functional languages, as well as having a number of unique language features. The primary characteristics are:- by-default referential transparency ("purity")
- by-default lazy evaluation
- a static type system based on System F
- optionally whitespace-sensitive syntax
- algebraic data types
- pattern matching on data
- Type classes
- ubiquitous use of currying
- syntax for list comprehensions, guards
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