This report defines the syntax for Haskell programs and an informal abstract semantics for the meaning of such programs. We leave as implementation. Haskell A Non-strict, Purely Functional Language. Revised: FIX THIS DATE The master version of the Haskell Report is at Any corrections or. The Haskell 98 Language and Libraries Revised Report & addenda.
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Haskell features a type system with type inference  and lazy evaluation. Haskell is based on the semanticsbut not the syntax, of the language Mirandawhich served to focus the efforts of the initial Haskell repogt group.
Following the release of Miranda by Research Software Ltd. Bymore than a dozen non-strictpurely functional programming languages existed.
Miranda was the most widely used, but it was proprietary software. At the conference on Functional Programming Languages and Computer Architecture FPCA ’87 in Portland, Oregon haskel98, there was a strong consensus that a committee be formed to define an open standard for such languages.
The committee’s purpose was to consolidate existing functional languages into a common one to serve as a basis for future research in functional-language design.
The haskrll98 version of Haskell “Haskell 1. In latethe series culminated in Haskell 98intended 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 creating extensions and variants of Haskell 98 via adding and incorporating experimental features.
The Haskell 98 Report: Introduction
In Februarythe Haskell 98 language standard was originally published as The Haskell 98 Report. In earlythe process of defining a successor to the Haskell 98 standard, informally named Haskell Primebegan.
The first revision, named Haskellwas announced in November  and published in July Haskell is an incremental update to the language, mostly incorporating several well-used and uncontroversial features previously enabled via compiler-specific flags.
Haskell features lazy evaluationlambda expressions, pattern matchinglist comprehension hazkell98, type classes and type polymorphism. It is a purely functional languagewhich means that functions generally have no side effects.
A distinct construct exists to represent side effects, orthogonal to the type of functions. A pure function can return a side effect that is subsequently executed, modeling the impure functions of other languages.
Haskell has a strongstatic type system based on Hindley—Milner type inference. Its principal innovation in this area is type classes, originally conceived as a principled way to add overloading to the language,  but since finding many more uses. The construct that represents side effects is an example of a monad. Monads are a general framework that can model different kinds of computation, including error handling, nondeterminismparsing and software transactional memory.
Monads are defined as ordinary datatypes, but Haskell provides some syntactic sugar for their use. Haskell has an open, published specification,  and multiple implementations exist. Its main implementation, the Glasgow Haskell Compiler GHCis both an interpreter and native-code compiler that runs on most platforms.
GHC is noted for its rich type system incorporating recent innovations such as generalized algebraic data types and type families.
Haskell (programming language)
The Computer Language Benchmarks Game also highlights its high-performance implementation of concurrency and parallelism. An active, growing community exists around the language, and more than 5, third-party open-source libraries and tools are available in the online package repository Hackage.
A “Hello world” program in Haskell only the last line is strictly necessary:. The factorial function in Haskell, defined in a few different ways:. Because the Integer type has arbitrary-precisionthis code will compute values such as factorial a ,digit numberwith no loss of precision.
Package: haskell98-report (20080907-8)
An implementation of an algorithm similar to quick sort over lists, where the first element is taken as the pivot:. All listed implementations are distributed under open source licenses. Haskell web frameworks exist,  including:. Jan-Willem Maessen, inand Simon Peyton Jonesindiscussed problems associated with lazy evaluation while also acknowledging the theoretical motives for it.
Ben Lippmeier designed Disciple  as a strict-by-default lazy by explicit annotation dialect of Haskell with a type-and-effect system, to address Haskell’s difficulties in reasoning about lazy evaluation and in using traditional data structures such as mutable arrays.
Robert Harperone of the authors of Standard MLhas given his reasons for not using Haskell to teach introductory programming. Among these are the difficulty of reasoning about resource use with non-strict evaluation, that lazy evaluation complicates the definition of data types and inductive reasoning,  and the “inferiority” of Haskell’s old class system compared to ML’s module system.
It was consistently criticised by developers due to the lack of good management of different versions of a particular library by default build tool, Cabal, in a dll hell. This has been addressed  by the release of the Stackwhich manages cabal, to do the work in a build.
Although Haskell has copious educational and conceptual type examples, frequently illustrated with the Integer and String types, their use is not the only way to program in Haskell; Integer type can be replaced, with Int or Word when performance is needed, and String type can be replaced with Text type to handle real-world situations more prudently.
Clean is a close, slightly older relative of Haskell. A series of languages inspired by Haskell, but with different type systems, have been developed, including:. Java virtual machine JVM based:. Haskell has served as a testbed for many new ideas in language design. There have been many Haskell variants produced, exploring new language ideas, including:.
The Haskell community meets regularly hasiell98 research and development activities.
The main events are:. Sincea series of organized hackathons has occurred, the Hawkell98 series, aimed at improving the programming language tools and libraries.
From Wikipedia, the free encyclopedia. Haskell announced . Retrieved 12 March Haskell Prime committee has formed”. Retrieved 6 May Retrieved 9 February Archived from the original PDF on 10 February Getting the Masses Hooked on Haskell”. Archived from the original on F also draws from Haskell particularly with regard to two advanced language features called sequence expressions and workflows. Retrieved 26 February Perl Foundation Perl 6 Wiki.
Archived from the original on 21 January Retrieved 23 April The Swift language is the product of tireless effort from a team of language experts, documentation gurus, compiler optimization ninjas, and an incredibly important internal dogfooding group who provided feedback to help refine and battle-test ideas. Of course, it also greatly benefited haskeell98 the experiences hard-won by many other languages in the field, drawing ideas from Objective-C, Rust, Haskell, Ruby, Python, C haskell988, CLU, and far too many others to list.
Retrieved 15 February Retrieved 18 December Retrieved 8 April Debian Haskell mailing list. Retrieved September 1, A Haskell Web Framework: Resource-bounded execution yields efficient iteration. Wearing the hair shirt: Invited talk at POPL Archived from the teport on 20 February Retrieved from ” https: Academic programming languages Educational programming languages Functional languages Haskell programming language family Literate programming Pattern matching programming reoort Programming languages created in Statically typed programming languages.
Pages using deprecated image syntax All articles with unsourced statements Articles with repott statements from February Articles containing potentially dated statements from May All articles containing potentially dated statements Articles with unsourced statements from April Articles with inconsistent citation formats Wikipedia articles with BNE identifiers Wikipedia articles with BNF identifiers Wikipedia articles with GND identifiers Wikipedia articles with LCCN identifiers Use dmy dates from March Repott with example Haskell code.
The Haskell 98 Report