Cabal-2.4.0.1: A framework for packaging Haskell software

Description

Synopsis

# Documentation

data Language Source #

This represents a Haskell language dialect.

Language Extensions are interpreted relative to one of these base languages.

Constructors

Instances

data Extension Source #

This represents language extensions beyond a base Language definition (such as Haskell98) that are supported by some implementations, usually in some special mode.

Where applicable, references are given to an implementation's official documentation.

Constructors

 EnableExtension KnownExtension Enable a known extension DisableExtension KnownExtension Disable a known extension UnknownExtension String An unknown extension, identified by the name of its LANGUAGE pragma.
Instances
 OverlappingInstances Allow overlapping class instances, provided there is a unique most specific instance for each use.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XOverlappingInstances UndecidableInstances Ignore structural rules guaranteeing the termination of class instance resolution. Termination is guaranteed by a fixed-depth recursion stack, and compilation may fail if this depth is exceeded.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XUndecidableInstances IncoherentInstances Implies OverlappingInstances. Allow the implementation to choose an instance even when it is possible that further instantiation of types will lead to a more specific instance being applicable.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XIncoherentInstances DoRec (deprecated) Deprecated in favour of RecursiveDo.Old description: Allow recursive bindings in do blocks, using the rec keyword. See also RecursiveDo. RecursiveDo Allow recursive bindings in do blocks, using the rec keyword, or mdo, a variant of do.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XRecursiveDo ParallelListComp Provide syntax for writing list comprehensions which iterate over several lists together, like the zipWith family of functions.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XParallelListComp MultiParamTypeClasses Allow multiple parameters in a type class.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XMultiParamTypeClasses MonomorphismRestriction Enable the dreaded monomorphism restriction.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XNoMonomorphismRestriction FunctionalDependencies Allow a specification attached to a multi-parameter type class which indicates that some parameters are entirely determined by others. The implementation will check that this property holds for the declared instances, and will use this property to reduce ambiguity in instance resolution.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XFunctionalDependencies Rank2Types (deprecated) A synonym for RankNTypes.Old description: Like RankNTypes but does not allow a higher-rank type to itself appear on the left of a function arrow.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XRank2Types RankNTypes Allow a universally-quantified type to occur on the left of a function arrow.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XRankNTypes PolymorphicComponents (deprecated) A synonym for RankNTypes.Old description: Allow data constructors to have polymorphic arguments. Unlike RankNTypes, does not allow this for ordinary functions.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#arbitrary-rank-polymorphism ExistentialQuantification Allow existentially-quantified data constructors.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XExistentialQuantification ScopedTypeVariables Cause a type variable in a signature, which has an explicit forall quantifier, to scope over the definition of the accompanying value declaration.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XScopedTypeVariables PatternSignatures Deprecated, use ScopedTypeVariables instead. ImplicitParams Enable implicit function parameters with dynamic scope.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XImplicitParams FlexibleContexts Relax some restrictions on the form of the context of a type signature.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XFlexibleContexts FlexibleInstances Relax some restrictions on the form of the context of an instance declaration.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XFlexibleInstances EmptyDataDecls Allow data type declarations with no constructors.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XEmptyDataDecls CPP Run the C preprocessor on Haskell source code.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#language-pragma KindSignatures Allow an explicit kind signature giving the kind of types over which a type variable ranges.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XKindSignatures BangPatterns Enable a form of pattern which forces evaluation before an attempted match, and a form of strict let/where binding.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XBangPatterns TypeSynonymInstances Allow type synonyms in instance heads.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XTypeSynonymInstances TemplateHaskell Enable Template Haskell, a system for compile-time metaprogramming.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XTemplateHaskell ForeignFunctionInterface Enable the Foreign Function Interface. In GHC, implements the standard Haskell 98 Foreign Function Interface Addendum, plus some GHC-specific extensions.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#language-pragma Arrows Enable arrow notation.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XArrows Generics (deprecated) Enable generic type classes, with default instances defined in terms of the algebraic structure of a type.https://haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#generic-classes ImplicitPrelude Enable the implicit importing of the module Prelude. When disabled, when desugaring certain built-in syntax into ordinary identifiers, use whatever is in scope rather than the Prelude -- version.https://haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#rebindable-syntax-and-the-implicit-prelude-import NamedFieldPuns Enable syntax for implicitly binding local names corresponding to the field names of a record. Puns bind specific names, unlike RecordWildCards.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XNamedFieldPuns PatternGuards Enable a form of guard which matches a pattern and binds variables.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XPatternGuards GeneralizedNewtypeDeriving Allow a type declared with newtype to use deriving for any class with an instance for the underlying type.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XGeneralizedNewtypeDeriving ExtensibleRecords Enable the "Trex" extensible records system.http://haskell.org/hugs/pages/users_guide/hugs-only.html#TREX RestrictedTypeSynonyms Enable type synonyms which are transparent in some definitions and opaque elsewhere, as a way of implementing abstract datatypes.http://haskell.org/hugs/pages/users_guide/restricted-synonyms.html HereDocuments Enable an alternate syntax for string literals, with string templating.http://haskell.org/hugs/pages/users_guide/here-documents.html MagicHash Allow the character # as a postfix modifier on identifiers. Also enables literal syntax for unboxed values.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XMagicHash TypeFamilies Allow data types and type synonyms which are indexed by types, i.e. ad-hoc polymorphism for types.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XTypeFamilies StandaloneDeriving Allow a standalone declaration which invokes the type class deriving mechanism.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XStandaloneDeriving UnicodeSyntax Allow certain Unicode characters to stand for certain ASCII character sequences, e.g. keywords and punctuation.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XUnicodeSyntax UnliftedFFITypes Allow the use of unboxed types as foreign types, e.g. in foreign import and foreign export.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#language-options InterruptibleFFI Enable interruptible FFI.https://haskell.org/ghc/docs/latest/html/users_guide/ffi-chap.html#interruptible-foreign-calls CApiFFI Allow use of CAPI FFI calling convention (foreign import capi).https://haskell.org/ghc/docs/latest/html/users_guide/ffi-chap.html#the-capi-calling-convention LiberalTypeSynonyms Defer validity checking of types until after expanding type synonyms, relaxing the constraints on how synonyms may be used.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XLiberalTypeSynonyms TypeOperators Allow the name of a type constructor, type class, or type variable to be an infix operator. * https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XTypeOperators RecordWildCards Enable syntax for implicitly binding local names corresponding to the field names of a record. A wildcard binds all unmentioned names, unlike NamedFieldPuns.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XRecordWildCards RecordPuns Deprecated, use NamedFieldPuns instead. DisambiguateRecordFields Allow a record field name to be disambiguated by the type of the record it's in.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDisambiguateRecordFields TraditionalRecordSyntax Enable traditional record syntax (as supported by Haskell 98)https://haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#traditional-record-syntax OverloadedStrings Enable overloading of string literals using a type class, much like integer literals.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XOverloadedStrings GADTs Enable generalized algebraic data types, in which type variables may be instantiated on a per-constructor basis. Implies GADTSyntax.https://haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#generalised-algebraic-data-types-gadts GADTSyntax Enable GADT syntax for declaring ordinary algebraic datatypes.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XGADTSyntax MonoPatBinds (deprecated) Has no effect.Old description: Make pattern bindings monomorphic.https://downloads.haskell.org/~ghc/7.6.3/docs/html/users_guide/monomorphism.html RelaxedPolyRec Relax the requirements on mutually-recursive polymorphic functions.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XRelaxedPolyRec ExtendedDefaultRules Allow default instantiation of polymorphic types in more situations.http://downloads.haskell.org/~ghc/latest/docs/html/users_guide/ghci.html#type-defaulting-in-ghci UnboxedTuples Enable unboxed tuples.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XUnboxedTuples DeriveDataTypeable Enable deriving for classes Typeable and Data.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveDataTypeable DeriveGeneric Enable deriving for Generic and Generic1.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveGeneric DefaultSignatures Enable support for default signatures.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDefaultSignatures InstanceSigs Allow type signatures to be specified in instance declarations.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XInstanceSigs ConstrainedClassMethods Allow a class method's type to place additional constraints on a class type variable.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XConstrainedClassMethods PackageImports Allow imports to be qualified by the package name the module is intended to be imported from, e.g.import "network" Network.Sockethttps://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XPackageImports ImpredicativeTypes (deprecated) Allow a type variable to be instantiated at a polymorphic type.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XImpredicativeTypes NewQualifiedOperators (deprecated) Change the syntax for qualified infix operators.http://www.haskell.org/ghc/docs/6.12.3/html/users_guide/syntax-extns.html#new-qualified-operators PostfixOperators Relax the interpretation of left operator sections to allow unary postfix operators.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XPostfixOperators QuasiQuotes Enable quasi-quotation, a mechanism for defining new concrete syntax for expressions and patterns.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XQuasiQuotes TransformListComp Enable generalized list comprehensions, supporting operations such as sorting and grouping.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XTransformListComp MonadComprehensions Enable monad comprehensions, which generalise the list comprehension syntax to work for any monad.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XMonadComprehensions ViewPatterns Enable view patterns, which match a value by applying a function and matching on the result.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XViewPatterns XmlSyntax Allow concrete XML syntax to be used in expressions and patterns, as per the Haskell Server Pages extension language: http://www.haskell.org/haskellwiki/HSP. The ideas behind it are discussed in the paper "Haskell Server Pages through Dynamic Loading" by Niklas Broberg, from Haskell Workshop '05. RegularPatterns Allow regular pattern matching over lists, as discussed in the paper "Regular Expression Patterns" by Niklas Broberg, Andreas Farre and Josef Svenningsson, from ICFP '04. TupleSections Enable the use of tuple sections, e.g. (, True) desugars into x -> (x, True).https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XTupleSections GHCForeignImportPrim Allow GHC primops, written in C--, to be imported into a Haskell file. NPlusKPatterns Support for patterns of the form n + k, where k is an integer literal.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XNPlusKPatterns DoAndIfThenElse Improve the layout rule when if expressions are used in a do block. MultiWayIf Enable support for multi-way if-expressions.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XMultiWayIf LambdaCase Enable support lambda-case expressions.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XLambdaCase RebindableSyntax Makes much of the Haskell sugar be desugared into calls to the function with a particular name that is in scope.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XRebindableSyntax ExplicitForAll Make forall a keyword in types, which can be used to give the generalisation explicitly.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XExplicitForAll DatatypeContexts Allow contexts to be put on datatypes, e.g. the Eq a in data Eq a => Set a = NilSet | ConsSet a (Set a).https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDatatypeContexts MonoLocalBinds Local (let and where) bindings are monomorphic.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XMonoLocalBinds DeriveFunctor Enable deriving for the Functor class.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveFunctor DeriveTraversable Enable deriving for the Traversable class.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveTraversable DeriveFoldable Enable deriving for the Foldable class.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveFoldable NondecreasingIndentation Enable non-decreasing indentation for do blocks.https://haskell.org/ghc/docs/latest/html/users_guide/bugs.html#context-free-syntax SafeImports Allow imports to be qualified with a safe keyword that requires the imported module be trusted as according to the Safe Haskell definition of trust.import safe Network.Sockethttps://haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#safe-imports Safe Compile a module in the Safe, Safe Haskell mode -- a restricted form of the Haskell language to ensure type safety.https://www.haskell.org/ghc/docs/latest/html/users_guide/safe_haskell.html#ghc-flag--XSafe Trustworthy Compile a module in the Trustworthy, Safe Haskell mode -- no restrictions apply but the module is marked as trusted as long as the package the module resides in is trusted.https://www.haskell.org/ghc/docs/latest/html/users_guide/safe_haskell.html#ghc-flag--XTrustworthy Unsafe Compile a module in the Unsafe, Safe Haskell mode so that modules compiled using Safe, Safe Haskell mode can't import it.https://www.haskell.org/ghc/docs/latest/html/users_guide/safe_haskell.html#ghc-flag--XUnsafe ConstraintKinds Allow type classimplicit parameterequality constraints to be used as types with the special kind constraint. Also generalise the (ctxt => ty) syntax so that any type of kind constraint can occur before the arrow.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XConstraintKinds PolyKinds Enable kind polymorphism.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XPolyKinds DataKinds Enable datatype promotion.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDataKinds ParallelArrays Enable parallel arrays syntax ([:, :]) for Data Parallel Haskell.http://www.haskell.org/haskellwiki/GHC/Data_Parallel_Haskell RoleAnnotations Enable explicit role annotations, like in (type role Foo representational representational).https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XRoleAnnotations OverloadedLists Enable overloading of list literals, arithmetic sequences and list patterns using the IsList type class.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XOverloadedLists EmptyCase Enable case expressions that have no alternatives. Also applies to lambda-case expressions if they are enabled.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XEmptyCase AutoDeriveTypeable (deprecated) Deprecated in favour of DeriveDataTypeable.Old description: Triggers the generation of derived Typeable instances for every datatype and type class declaration.https://haskell.org/ghc/docs/7.8.4/html/users_guide/deriving.html#auto-derive-typeable NegativeLiterals Desugars negative literals directly (without using negate).https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XNegativeLiterals BinaryLiterals Allow the use of binary integer literal syntax (e.g. 0b11001001 to denote 201).https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XBinaryLiterals NumDecimals Allow the use of floating literal syntax for all instances of Num, including Int and Integer.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XNumDecimals NullaryTypeClasses Enable support for type classes with no type parameter.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XNullaryTypeClasses ExplicitNamespaces Enable explicit namespaces in module import/export lists.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XExplicitNamespaces AllowAmbiguousTypes Allow the user to write ambiguous types, and the type inference engine to infer them.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XAllowAmbiguousTypes JavaScriptFFI Enable foreign import javascript. PatternSynonyms Allow giving names to and abstracting over patterns.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XPatternSynonyms PartialTypeSignatures Allow anonymous placeholders (underscore) inside type signatures. The type inference engine will generate a message describing the type inferred at the hole's location.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XPartialTypeSignatures NamedWildCards Allow named placeholders written with a leading underscore inside type signatures. Wildcards with the same name unify to the same type.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XNamedWildCards DeriveAnyClass Enable deriving for any class.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveAnyClass DeriveLift Enable deriving for the Lift class.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveLift StaticPointers Enable support for 'static pointers' (and the static keyword) to refer to globally stable names, even across different programs.https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XStaticPointers StrictData Switches data type declarations to be strict by default (as if they had a bang using BangPatterns), and allow opt-in field laziness using ~.https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#ghc-flag--XStrictData Strict Switches all pattern bindings to be strict by default (as if they had a bang using BangPatterns), ordinary patterns are recovered using ~. Implies StrictData.https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#ghc-flag--XStrict ApplicativeDo Allows do-notation for types that are Applicative as well as Monad. When enabled, desugaring do notation tries to use (*) and fmap and join as far as possible. DuplicateRecordFields Allow records to use duplicated field labels for accessors. TypeApplications Enable explicit type applications with the syntax id @Int. TypeInType Dissolve the distinction between types and kinds, allowing the compiler to reason about kind equality and therefore enabling GADTs to be promoted to the type-level. UndecidableSuperClasses Allow recursive (and therefore undecideable) super-class relationships. MonadFailDesugaring A temporary extension to help library authors check if their code will compile with the new planned desugaring of fail. TemplateHaskellQuotes A subset of TemplateHaskell including only quoting. OverloadedLabels Allows use of the #label syntax. TypeFamilyDependencies Allow functional dependency annotations on type families to declare them as injective. DerivingStrategies Allow multiple deriving clauses, each optionally qualified with a strategy. UnboxedSums Enable the use of unboxed sum syntax. HexFloatLiterals Allow use of hexadecimal literal notation for floating-point values. BlockArguments Allow do blocks etc. in argument position. NumericUnderscores Allow use of underscores in numeric literals. QuantifiedConstraints Allow forall in constraints. StarIsType Have * refer to Type.