{-# LANGUAGE DeriveDataTypeable #-} {-# LANGUAGE DeriveGeneric #-} ----------------------------------------------------------------------------- -- | -- Module : Language.Haskell.Extension -- Copyright : Isaac Jones 2003-2004 -- License : BSD3 -- -- Maintainer : libraries@haskell.org -- Portability : portable -- -- Haskell language dialects and extensions module Language.Haskell.Extension ( Language(..), knownLanguages, classifyLanguage, Extension(..), KnownExtension(..), deprecatedExtensions, classifyExtension, ) where import Prelude () import Distribution.Compat.Prelude import Data.Array (Array, accumArray, bounds, Ix(inRange), (!)) import Distribution.Parsec import Distribution.Pretty import qualified Distribution.Compat.CharParsing as P import qualified Text.PrettyPrint as Disp -- ------------------------------------------------------------ -- * Language -- ------------------------------------------------------------ -- | This represents a Haskell language dialect. -- -- Language 'Extension's are interpreted relative to one of these base -- languages. -- data Language = -- | The Haskell 98 language as defined by the Haskell 98 report. -- <http://haskell.org/onlinereport/> Haskell98 -- | The Haskell 2010 language as defined by the Haskell 2010 report. -- <http://www.haskell.org/onlinereport/haskell2010> | Haskell2010 -- | An unknown language, identified by its name. | UnknownLanguage String deriving (Generic, Show, Read, Eq, Typeable, Data) instance Binary Language instance NFData Language where rnf = genericRnf knownLanguages :: [Language] knownLanguages = [Haskell98, Haskell2010] instance Pretty Language where pretty (UnknownLanguage other) = Disp.text other pretty other = Disp.text (show other) instance Parsec Language where parsec = classifyLanguage <$> P.munch1 isAlphaNum classifyLanguage :: String -> Language classifyLanguage = \str -> case lookup str langTable of Just lang -> lang Nothing -> UnknownLanguage str where langTable = [ (show lang, lang) | lang <- knownLanguages ] -- ------------------------------------------------------------ -- * Extension -- ------------------------------------------------------------ -- Note: if you add a new 'KnownExtension': -- -- * also add it to the Distribution.Simple.X.languageExtensions lists -- (where X is each compiler: GHC, UHC, HaskellSuite) -- -- | 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. data Extension = -- | Enable a known extension EnableExtension KnownExtension -- | Disable a known extension | DisableExtension KnownExtension -- | An unknown extension, identified by the name of its @LANGUAGE@ -- pragma. | UnknownExtension String deriving (Generic, Show, Read, Eq, Ord, Typeable, Data) instance Binary Extension instance NFData Extension where rnf = genericRnf data KnownExtension = -- | 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> OverlappingInstances -- | 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> | UndecidableInstances -- | 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> | IncoherentInstances -- | /(deprecated)/ Deprecated in favour of 'RecursiveDo'. -- -- Old description: Allow recursive bindings in @do@ blocks, using -- the @rec@ keyword. See also 'RecursiveDo'. | DoRec -- | 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> | RecursiveDo -- | 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> | ParallelListComp -- | Allow multiple parameters in a type class. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XMultiParamTypeClasses> | MultiParamTypeClasses -- | Enable the dreaded monomorphism restriction. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XNoMonomorphismRestriction> | MonomorphismRestriction -- | 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> | FunctionalDependencies -- | /(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> | Rank2Types -- | 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> | RankNTypes -- | /(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> | PolymorphicComponents -- | Allow existentially-quantified data constructors. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XExistentialQuantification> | ExistentialQuantification -- | 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> | ScopedTypeVariables -- | Deprecated, use 'ScopedTypeVariables' instead. | PatternSignatures -- | Enable implicit function parameters with dynamic scope. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XImplicitParams> | ImplicitParams -- | 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> | FlexibleContexts -- | 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> | FlexibleInstances -- | Allow data type declarations with no constructors. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XEmptyDataDecls> | EmptyDataDecls -- | Run the C preprocessor on Haskell source code. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#language-pragma> | CPP -- | 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> | KindSignatures -- | 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> | BangPatterns -- | Allow type synonyms in instance heads. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XTypeSynonymInstances> | TypeSynonymInstances -- | 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> | TemplateHaskell -- | 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> | ForeignFunctionInterface -- | Enable arrow notation. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XArrows> | Arrows -- | /(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> | Generics -- | 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> | ImplicitPrelude -- | 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> | NamedFieldPuns -- | 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> | PatternGuards -- | 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> | GeneralizedNewtypeDeriving -- Synonym for GeneralizedNewtypeDeriving added in GHC 8.6.1. | GeneralisedNewtypeDeriving -- | Enable the \"Trex\" extensible records system. -- -- * <http://haskell.org/hugs/pages/users_guide/hugs-only.html#TREX> | ExtensibleRecords -- | 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> | RestrictedTypeSynonyms -- | Enable an alternate syntax for string literals, -- with string templating. -- -- * <http://haskell.org/hugs/pages/users_guide/here-documents.html> | HereDocuments -- | 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> | MagicHash -- | 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> | TypeFamilies -- | 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> | StandaloneDeriving -- | 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> | UnicodeSyntax -- | 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> | UnliftedFFITypes -- | Enable interruptible FFI. -- -- * <https://haskell.org/ghc/docs/latest/html/users_guide/ffi-chap.html#interruptible-foreign-calls> | InterruptibleFFI -- | 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> | CApiFFI -- | 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> | LiberalTypeSynonyms -- | 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> | TypeOperators -- | 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> | RecordWildCards -- | Deprecated, use 'NamedFieldPuns' instead. | RecordPuns -- | 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> | DisambiguateRecordFields -- | Enable traditional record syntax (as supported by Haskell 98) -- -- * <https://haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#traditional-record-syntax> | TraditionalRecordSyntax -- | 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> | OverloadedStrings -- | 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> | GADTs -- | Enable GADT syntax for declaring ordinary algebraic datatypes. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XGADTSyntax> | GADTSyntax -- | /(deprecated)/ Has no effect. -- -- Old description: Make pattern bindings monomorphic. -- -- * <https://downloads.haskell.org/~ghc/7.6.3/docs/html/users_guide/monomorphism.html> | MonoPatBinds -- | Relax the requirements on mutually-recursive polymorphic -- functions. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XRelaxedPolyRec> | RelaxedPolyRec -- | 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> | ExtendedDefaultRules -- | Enable unboxed tuples. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XUnboxedTuples> | UnboxedTuples -- | Enable @deriving@ for classes 'Data.Typeable.Typeable' and -- 'Data.Generics.Data'. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveDataTypeable> | DeriveDataTypeable -- | Enable @deriving@ for 'GHC.Generics.Generic' and 'GHC.Generics.Generic1'. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveGeneric> | DeriveGeneric -- | Enable support for default signatures. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDefaultSignatures> | DefaultSignatures -- | 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> | InstanceSigs -- | 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> | ConstrainedClassMethods -- | Allow imports to be qualified by the package name the module is -- intended to be imported from, e.g. -- -- > import "network" Network.Socket -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XPackageImports> | PackageImports -- | /(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> | ImpredicativeTypes -- | /(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> | NewQualifiedOperators -- | 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> | PostfixOperators -- | 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> | QuasiQuotes -- | 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> | TransformListComp -- | 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> | MonadComprehensions -- | 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> | ViewPatterns -- | 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. | XmlSyntax -- | 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. | RegularPatterns -- | 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> | TupleSections -- | Allow GHC primops, written in C--, to be imported into a Haskell -- file. | GHCForeignImportPrim -- | 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> | NPlusKPatterns -- | Improve the layout rule when @if@ expressions are used in a @do@ -- block. | DoAndIfThenElse -- | Enable support for multi-way @if@-expressions. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XMultiWayIf> | MultiWayIf -- | Enable support lambda-@case@ expressions. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XLambdaCase> | LambdaCase -- | 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> | RebindableSyntax -- | 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> | ExplicitForAll -- | 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> | DatatypeContexts -- | Local (@let@ and @where@) bindings are monomorphic. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XMonoLocalBinds> | MonoLocalBinds -- | Enable @deriving@ for the 'Data.Functor.Functor' class. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveFunctor> | DeriveFunctor -- | Enable @deriving@ for the 'Data.Traversable.Traversable' class. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveTraversable> | DeriveTraversable -- | Enable @deriving@ for the 'Data.Foldable.Foldable' class. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveFoldable> | DeriveFoldable -- | Enable non-decreasing indentation for @do@ blocks. -- -- * <https://haskell.org/ghc/docs/latest/html/users_guide/bugs.html#context-free-syntax> | NondecreasingIndentation -- | 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.Socket -- -- * <https://haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#safe-imports> | SafeImports -- | 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> | Safe -- | 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> | Trustworthy -- | 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> | Unsafe -- | Allow type class/implicit parameter/equality 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> | ConstraintKinds -- | Enable kind polymorphism. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XPolyKinds> | PolyKinds -- | Enable datatype promotion. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDataKinds> | DataKinds -- | Enable parallel arrays syntax (@[:@, @:]@) for /Data Parallel Haskell/. -- -- * <http://www.haskell.org/haskellwiki/GHC/Data_Parallel_Haskell> | ParallelArrays -- | 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> | RoleAnnotations -- | 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> | OverloadedLists -- | 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> | EmptyCase -- | /(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> | AutoDeriveTypeable -- | Desugars negative literals directly (without using negate). -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XNegativeLiterals> | NegativeLiterals -- | 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> | BinaryLiterals -- | 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> | NumDecimals -- | 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> | NullaryTypeClasses -- | Enable explicit namespaces in module import/export lists. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XExplicitNamespaces> | ExplicitNamespaces -- | 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> | AllowAmbiguousTypes -- | Enable @foreign import javascript@. | JavaScriptFFI -- | Allow giving names to and abstracting over patterns. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XPatternSynonyms> | PatternSynonyms -- | 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> | PartialTypeSignatures -- | 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> | NamedWildCards -- | Enable @deriving@ for any class. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveAnyClass> | DeriveAnyClass -- | Enable @deriving@ for the 'Language.Haskell.TH.Syntax.Lift' class. -- -- * <https://www.haskell.org/ghc/docs/latest/html/users_guide/glasgow_exts.html#ghc-flag--XDeriveLift> | DeriveLift -- | 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> | StaticPointers -- | 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> | StrictData -- | 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> | Strict -- | 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. | ApplicativeDo -- | Allow records to use duplicated field labels for accessors. | DuplicateRecordFields -- | Enable explicit type applications with the syntax @id \@Int@. | TypeApplications -- | 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. | TypeInType -- | Allow recursive (and therefore undecidable) super-class relationships. | UndecidableSuperClasses -- | A temporary extension to help library authors check if their -- code will compile with the new planned desugaring of fail. | MonadFailDesugaring -- | A subset of @TemplateHaskell@ including only quoting. | TemplateHaskellQuotes -- | Allows use of the @#label@ syntax. | OverloadedLabels -- | Allow functional dependency annotations on type families to declare them -- as injective. | TypeFamilyDependencies -- | Allow multiple @deriving@ clauses, each optionally qualified with a -- /strategy/. | DerivingStrategies -- | Enable deriving instances via types of the same runtime representation. -- Implies 'DerivingStrategies'. | DerivingVia -- | Enable the use of unboxed sum syntax. | UnboxedSums -- | Allow use of hexadecimal literal notation for floating-point values. | HexFloatLiterals -- | Allow @do@ blocks etc. in argument position. | BlockArguments -- | Allow use of underscores in numeric literals. | NumericUnderscores -- | Allow @forall@ in constraints. | QuantifiedConstraints -- | Have @*@ refer to @Type@. | StarIsType -- | Liberalises deriving to provide instances for empty data types. -- -- * <https://downloads.haskell.org/~ghc/latest/docs/html/users_guide/glasgow_exts.html#deriving-instances-for-empty-data-types> | EmptyDataDeriving deriving (Generic, Show, Read, Eq, Ord, Enum, Bounded, Typeable, Data) instance Binary KnownExtension instance NFData KnownExtension where rnf = genericRnf -- | Extensions that have been deprecated, possibly paired with another -- extension that replaces it. -- deprecatedExtensions :: [(Extension, Maybe Extension)] deprecatedExtensions = [ (EnableExtension RecordPuns, Just (EnableExtension NamedFieldPuns)) , (EnableExtension PatternSignatures, Just (EnableExtension ScopedTypeVariables)) ] -- NOTE: when adding deprecated extensions that have new alternatives -- we must be careful to make sure that the deprecation messages are -- valid. We must not recommend aliases that cannot be used with older -- compilers, perhaps by adding support in Cabal to translate the new -- name to the old one for older compilers. Otherwise we are in danger -- of the scenario in ticket #689. instance Pretty Extension where pretty (UnknownExtension other) = Disp.text other pretty (EnableExtension ke) = Disp.text (show ke) pretty (DisableExtension ke) = Disp.text ("No" ++ show ke) instance Parsec Extension where parsec = classifyExtension <$> P.munch1 isAlphaNum instance Pretty KnownExtension where pretty ke = Disp.text (show ke) classifyExtension :: String -> Extension classifyExtension string = case classifyKnownExtension string of Just ext -> EnableExtension ext Nothing -> case string of 'N':'o':string' -> case classifyKnownExtension string' of Just ext -> DisableExtension ext Nothing -> UnknownExtension string _ -> UnknownExtension string -- | 'read' for 'KnownExtension's is really really slow so for the Text -- instance -- what we do is make a simple table indexed off the first letter in the -- extension name. The extension names actually cover the range @'A'-'Z'@ -- pretty densely and the biggest bucket is 7 so it's not too bad. We just do -- a linear search within each bucket. -- -- This gives an order of magnitude improvement in parsing speed, and it'll -- also allow us to do case insensitive matches in future if we prefer. -- classifyKnownExtension :: String -> Maybe KnownExtension classifyKnownExtension "" = Nothing classifyKnownExtension string@(c : _) | inRange (bounds knownExtensionTable) c = lookup string (knownExtensionTable ! c) | otherwise = Nothing knownExtensionTable :: Array Char [(String, KnownExtension)] knownExtensionTable = accumArray (flip (:)) [] ('A', 'Z') [ (head str, (str, extension)) | extension <- [toEnum 0 ..] , let str = show extension ]