% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
-HsDecls: Abstract syntax: global declarations
-Definitions for: @TyDecl@ and @oCnDecl@, @ClassDecl@,
-@InstDecl@, @DefaultDecl@ and @ForeignDecl@.
\begin{code}
{-# OPTIONS -fno-warn-incomplete-patterns #-}
-- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
-- for details
+-- | Abstract syntax of global declarations.
+--
+-- Definitions for: @TyDecl@ and @ConDecl@, @ClassDecl@,
+-- @InstDecl@, @DefaultDecl@ and @ForeignDecl@.
module HsDecls (
- HsDecl(..), LHsDecl, TyClDecl(..), LTyClDecl,
- InstDecl(..), LInstDecl, DerivDecl(..), LDerivDecl, NewOrData(..),
- FamilyFlavour(..),
- RuleDecl(..), LRuleDecl, RuleBndr(..),
- DefaultDecl(..), LDefaultDecl, SpliceDecl(..),
- ForeignDecl(..), LForeignDecl, ForeignImport(..), ForeignExport(..),
- CImportSpec(..), FoType(..),
- ConDecl(..), ResType(..), ConDeclField(..), LConDecl,
- HsConDeclDetails, hsConDeclArgTys,
- DocDecl(..), LDocDecl, docDeclDoc,
- WarnDecl(..), LWarnDecl,
- HsGroup(..), emptyRdrGroup, emptyRnGroup, appendGroups,
- tcdName, tyClDeclNames, tyClDeclTyVars,
- isClassDecl, isSynDecl, isDataDecl, isTypeDecl, isFamilyDecl,
- isFamInstDecl,
- countTyClDecls,
- instDeclATs,
- collectRuleBndrSigTys,
- ) where
+ -- * Toplevel declarations
+ HsDecl(..), LHsDecl,
+ -- ** Class or type declarations
+ TyClDecl(..), LTyClDecl,
+ isClassDecl, isSynDecl, isDataDecl, isTypeDecl, isFamilyDecl,
+ isFamInstDecl, tcdName, tyClDeclNames, tyClDeclTyVars,
+ countTyClDecls,
+ -- ** Instance declarations
+ InstDecl(..), LInstDecl, NewOrData(..), FamilyFlavour(..),
+ instDeclATs,
+ -- ** Standalone deriving declarations
+ DerivDecl(..), LDerivDecl,
+ -- ** @RULE@ declarations
+ RuleDecl(..), LRuleDecl, RuleBndr(..),
+ collectRuleBndrSigTys,
+ -- ** @default@ declarations
+ DefaultDecl(..), LDefaultDecl,
+ -- ** Top-level template haskell splice
+ SpliceDecl(..),
+ -- ** Foreign function interface declarations
+ ForeignDecl(..), LForeignDecl, ForeignImport(..), ForeignExport(..),
+ CImportSpec(..), FoType(..),
+ -- ** Data-constructor declarations
+ ConDecl(..), LConDecl, ResType(..), ConDeclField(..),
+ HsConDeclDetails, hsConDeclArgTys,
+ -- ** Document comments
+ DocDecl(..), LDocDecl, docDeclDoc,
+ -- ** Deprecations
+ WarnDecl(..), LWarnDecl,
+
+ -- * Grouping
+ HsGroup(..), emptyRdrGroup, emptyRnGroup, appendGroups,
+) where
-- friends:
import {-# SOURCE #-} HsExpr( HsExpr, pprExpr )
\begin{code}
type LHsDecl id = Located (HsDecl id)
+-- | A Haskell Declaration
data HsDecl id
- = TyClD (TyClDecl id)
- | InstD (InstDecl id)
+ = TyClD (TyClDecl id) -- ^ A type or class declaration.
+ | InstD (InstDecl id) -- ^ An instance declaration.
| DerivD (DerivDecl id)
| ValD (HsBind id)
| SigD (Sig id)
--
-- The latter is for class methods only
--- A [HsDecl] is categorised into a HsGroup before being
+-- | A 'HsDecl' is categorised into a 'HsGroup' before being
-- fed to the renamer.
data HsGroup id
= HsGroup {
type LTyClDecl name = Located (TyClDecl name)
+-- | A type or class declaration.
data TyClDecl name
= ForeignType {
tcdLName :: Located name,
tcdFoType :: FoType
}
- -- type/data/newtype family T :: *->*
- | TyFamily { tcdFlavour:: FamilyFlavour, -- type, new, or data
+
+ | -- | @type/data/newtype family T :: *->*@
+ TyFamily { tcdFlavour:: FamilyFlavour, -- type, new, or data
tcdLName :: Located name, -- type constructor
tcdTyVars :: [LHsTyVarBndr name], -- type variables
tcdKind :: Maybe Kind -- result kind
}
- -- Declares a data type or newtype, giving its construcors
- -- data/newtype T a = <constrs>
- -- data/newtype instance T [a] = <constrs>
- | TyData { tcdND :: NewOrData,
- tcdCtxt :: LHsContext name, -- Context
- tcdLName :: Located name, -- Type constructor
-
- tcdTyVars :: [LHsTyVarBndr name], -- Type variables
-
- tcdTyPats :: Maybe [LHsType name], -- Type patterns
- -- Just [t1..tn] for data instance T t1..tn = ...
- -- in this case tcdTyVars = fv( tcdTyPats )
- -- Nothing for everything else
- tcdKindSig:: Maybe Kind, -- Optional kind sig
- -- (Just k) for a GADT-style 'data', or 'data
- -- instance' decl with explicit kind sig
+ | -- | Declares a data type or newtype, giving its construcors
+ -- @
+ -- data/newtype T a = <constrs>
+ -- data/newtype instance T [a] = <constrs>
+ -- @
+ TyData { tcdND :: NewOrData,
+ tcdCtxt :: LHsContext name, -- ^ Context
+ tcdLName :: Located name, -- ^ Type constructor
- tcdCons :: [LConDecl name], -- Data constructors
- -- For data T a = T1 | T2 a
- -- the LConDecls all have ResTyH98
- -- For data T a where { T1 :: T a }
- -- the LConDecls all have ResTyGADT
+ tcdTyVars :: [LHsTyVarBndr name], -- ^ Type variables
+
+ tcdTyPats :: Maybe [LHsType name],
+ -- ^ Type patterns.
+ --
+ -- @Just [t1..tn]@ for @data instance T t1..tn = ...@
+ -- in this case @tcdTyVars = fv( tcdTyPats )@.
+ -- @Nothing@ for everything else.
+
+ tcdKindSig:: Maybe Kind,
+ -- ^ Optional kind signature.
+ --
+ -- @(Just k)@ for a GADT-style @data@, or @data
+ -- instance@ decl with explicit kind sig
+
+ tcdCons :: [LConDecl name],
+ -- ^ Data constructors
+ --
+ -- For @data T a = T1 | T2 a@
+ -- the 'LConDecl's all have 'ResTyH98'.
+ -- For @data T a where { T1 :: T a }@
+ -- the 'LConDecls' all have 'ResTyGADT'.
tcdDerivs :: Maybe [LHsType name]
- -- Derivings; Nothing => not specified
- -- Just [] => derive exactly what is asked
+ -- ^ Derivings; @Nothing@ => not specified,
+ -- @Just []@ => derive exactly what is asked
+ --
-- These "types" must be of form
+ -- @
-- forall ab. C ty1 ty2
+ -- @
-- Typically the foralls and ty args are empty, but they
-- are non-empty for the newtype-deriving case
}
- | TySynonym { tcdLName :: Located name, -- type constructor
- tcdTyVars :: [LHsTyVarBndr name], -- type variables
- tcdTyPats :: Maybe [LHsType name], -- Type patterns
+ | TySynonym { tcdLName :: Located name, -- ^ type constructor
+ tcdTyVars :: [LHsTyVarBndr name], -- ^ type variables
+ tcdTyPats :: Maybe [LHsType name], -- ^ Type patterns
-- See comments for tcdTyPats in TyData
-- 'Nothing' => vanilla type synonym
- tcdSynRhs :: LHsType name -- synonym expansion
+ tcdSynRhs :: LHsType name -- ^ synonym expansion
}
- | ClassDecl { tcdCtxt :: LHsContext name, -- Context...
- tcdLName :: Located name, -- Name of the class
- tcdTyVars :: [LHsTyVarBndr name], -- Class type variables
- tcdFDs :: [Located (FunDep name)], -- Functional deps
- tcdSigs :: [LSig name], -- Methods' signatures
- tcdMeths :: LHsBinds name, -- Default methods
- tcdATs :: [LTyClDecl name], -- Associated types; ie
+ | ClassDecl { tcdCtxt :: LHsContext name, -- ^ Context...
+ tcdLName :: Located name, -- ^ Name of the class
+ tcdTyVars :: [LHsTyVarBndr name], -- ^ Class type variables
+ tcdFDs :: [Located (FunDep name)], -- ^ Functional deps
+ tcdSigs :: [LSig name], -- ^ Methods' signatures
+ tcdMeths :: LHsBinds name, -- ^ Default methods
+ tcdATs :: [LTyClDecl name], -- ^ Associated types; ie
-- only 'TyFamily' and
-- 'TySynonym'; the
-- latter for defaults
- tcdDocs :: [LDocDecl name] -- Haddock docs
+ tcdDocs :: [LDocDecl name] -- ^ Haddock docs
}
data NewOrData
- = NewType -- "newtype Blah ..."
- | DataType -- "data Blah ..."
+ = NewType -- ^ @newtype Blah ...@
+ | DataType -- ^ @data Blah ...@
deriving( Eq ) -- Needed because Demand derives Eq
data FamilyFlavour
- = TypeFamily -- "type family ..."
- | DataFamily -- "data family ..."
+ = TypeFamily -- ^ @type family ...@
+ | DataFamily -- ^ @data family ...@
\end{code}
Simple classifiers
\begin{code}
-isDataDecl, isTypeDecl, isSynDecl, isClassDecl, isFamilyDecl, isFamInstDecl ::
- TyClDecl name -> Bool
-
--- data/newtype or data/newtype instance declaration
+-- | @True@ <=> argument is a @data@\/@newtype@ or @data@\/@newtype instance@
+-- declaration.
+isDataDecl :: TyClDecl name -> Bool
isDataDecl (TyData {}) = True
isDataDecl _other = False
--- type or type instance declaration
+-- | type or type instance declaration
+isTypeDecl :: TyClDecl name -> Bool
isTypeDecl (TySynonym {}) = True
isTypeDecl _other = False
--- vanilla Haskell type synonym (ie, not a type instance)
+-- | vanilla Haskell type synonym (ie, not a type instance)
+isSynDecl :: TyClDecl name -> Bool
isSynDecl (TySynonym {tcdTyPats = Nothing}) = True
isSynDecl _other = False
--- type class
+-- | type class
+isClassDecl :: TyClDecl name -> Bool
isClassDecl (ClassDecl {}) = True
isClassDecl _ = False
--- type family declaration
+-- | type family declaration
+isFamilyDecl :: TyClDecl name -> Bool
isFamilyDecl (TyFamily {}) = True
isFamilyDecl _other = False
--- family instance (types, newtypes, and data types)
+-- | family instance (types, newtypes, and data types)
+isFamInstDecl :: TyClDecl name -> Bool
isFamInstDecl tydecl
| isTypeDecl tydecl
|| isDataDecl tydecl = isJust (tcdTyPats tydecl)
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