Known Haskell Extensions

Links

• Please see the explanation and template for writing descriptions of these extensions.
•  Cabal extension list
•  GHC extension related options
• [source:/ExtensionTables.hs Script] to generate the original tables
•  GHC survey results (including a large list of Haskell extensions)
•  Results of John Hughes' Haskell survey (also lists many extensions)

Support Matrix

Extension Name	GHC	NHC	HUGS	JHC
ForeignFunctionInterface	True	True	True	True
RecursiveDo	True	False	True	False
ParallelListComp	True	False	True	False
PatternGuards	True	False	False	False
Arrows	True	False	False	False
ScopedTypeVariables	True	False	True	False
PolymorphicComponents	True	False	True	False
Rank2Types	True	False	True	False
RankNTypes	True	False	False	False
ExistentialQuantification	True	True	True	False
NewtypeDeriving	True	False	False	True
ImplicitParams	True	False	True	False
LinearImplicitParams	True	False	False	False
EmptyDataDecls	True	True	True	True
NoMonomorphismRestriction	True	True	False	True
FlexibleContexts	True	False	True	?
FlexibleInstances	True	False	True	?
TypeSynonymInstances	True	False	True	True
MultiParamTypeClasses	True	False	True	False
OverlappingInstances	True	False	True	False
IncoherentInstances	True	False	True	False
UndecidableInstances	True	False	False	False
FunctionalDependencies	True	False	True	False
AssociatedTypes	False	False	False	False
CPP?	True	True	True	True
TemplateHaskell?	True	False	False	False
InlinePhase?	True	False	False	False
ContextStack?	True	False	False	False
Generics?	True	False	False	False
NoImplicitPrelude?	True	False	False	True
NamedFieldPuns?	False	True	False	False
ExtensibleRecords?	False	False	True	False
RestrictedTypeSynonyms?	False	False	True	False
HereDocuments?	False	False	True	False
Assertions?	True	?	False	True
Concurrency	True	False	Coop	Poor
KindAnnotations	True	False	False	True
GADTs	True	False	False	False
InfixTypeConstructors	True	False	False	True
LiberalTypeSynonyms	True	False	False	True
RebindableSyntax?	True	False	False	Some
RecursiveModules?	Partial	?	False	True
RewriteRules?	True	False	False	Int
UnboxedTypes?	True	False	False	Int
CoinductiveDictionaries?	?	False	False	False
PartialTypeSigs	False	False	False	False
Impredicativity?	?	False	False	False
ExplicitDictionaries?	False	False	False	False
KindPolymorphism?	False	False	False	False
DataKinds?	False	False	False	False
MagicUnderscore	False	False	False	True
NondecreasingIndentation	Partial	?	False	?
ClassAliases?	False	False	False	False
HierarchicalModules	True	True	True	True
DottedHierarchicalModules	False	False	False	True

Extensions supported by two compilers

• ForeignFunctionInterface
• RecursiveDo
• ParallelListComp
• ScopedTypeVariables
• PolymorphicComponents
• Rank2Types
• ExistentialQuantification
• ImplicitParams
• EmptyDataDecls
• NoMonomorphismRestriction
• FlexibleContexts
• FlexibleInstances
• TypeSynonymInstances
• MultiParamTypeClasses
• OverlappingInstances
• IncoherentInstances
• FunctionalDependencies
• CPP
• HierarchicalModules

Extensions used in fptools

Those mentioned in library .cabal files
CPP	11 libraries
ForeignFunctionInterface	4
MultiParamTypeClasses	3
OverlappingInstances	1
FunctionalDependencies	1
Additional extensions mentioned in source file "Portability" field
Concurrency	3 libraries
Local universal quantification	3
Extended exceptions	>1
Existentially quantified data constructors	1
STM	1