template-haskell-2.5.0.0

Portabilityportable
Stabilityexperimental
Maintainerlibraries@haskell.org

Language.Haskell.TH.Syntax

Description

Abstract syntax definitions for Template Haskell.

Synopsis

Documentation

class (Monad m, Functor m) => Quasi m whereSource

Methods

qNewName Source

Arguments

:: String
-> m Name

Fresh names

qReport Source

Arguments

:: Bool
-> String
-> m ()

Report an error (True) or warning (False) ...but carry on; use fail to stop

qRecover Source

Arguments

:: m a

the error handler

-> m a

action which may fail

-> m a

Recover from the monadic fail

qReify :: Name -> m Info Source

qClassInstances :: Name -> [Type] -> m [Name]Source

qLocation :: m Loc Source

qRunIO :: IO a -> m aSource

Input/output (dangerous)

Instances

class Lift t whereSource

Methods

lift :: t -> Q Exp Source

Instances

Lift a => Lift [a]
Lift a => Lift (Maybe a)
(Lift a, Lift b) => Lift (Either a b)
(Lift a, Lift b) => Lift (a, b)
(Lift a, Lift b, Lift c) => Lift (a, b, c)
(Lift a, Lift b, Lift c, Lift d) => Lift (a, b, c, d)
(Lift a, Lift b, Lift c, Lift d, Lift e) => Lift (a, b, c, d, e)
(Lift a, Lift b, Lift c, Lift d, Lift e, Lift f) => Lift (a, b, c, d, e, f)
(Lift a, Lift b, Lift c, Lift d, Lift e, Lift f, Lift g) => Lift (a, b, c, d, e, f, g)

liftString :: String -> Q Exp Source

data Q a Source

Instances

runQ :: Quasi m => Q a -> m aSource

report :: Bool -> String -> Q () Source

recover Source

Arguments

:: Q a

recover with this one

-> Q a

failing action

-> Q a

reify :: Name -> Q Info Source

reify looks up information about the Name

location :: Q Loc Source

location gives you the Location at which this computation is spliced.

runIO :: IO a -> Q aSource

The runIO function lets you run an I/O computation in the Q monad. Take care: you are guaranteed the ordering of calls to runIO within a single Q computation, but not about the order in which splices are run.

Note: for various murky reasons, stdout and stderr handles are not necesarily flushed when the compiler finishes running, so you should flush them yourself.

isClassInstance :: Name -> [Type] -> Q Bool Source

classInstances :: Name -> [Type] -> Q [Name]Source

classInstances looks up instaces of a class

Names

data Name Source

For global names (NameG ) we need a totally unique name, so we must include the name-space of the thing

For unique-numbered things (NameU ), we've got a unique reference anyway, so no need for name space

For dynamically bound thing (NameS ) we probably want them to in a context-dependent way, so again we don't want the name space. For example:

 let v = mkName "T" in [| data $v = $v |]

Here we use the same Name for both type constructor and data constructor

NameL and NameG are bound *outside* the TH syntax tree either globally (NameG) or locally (NameL). Ex:

 f x = $(h [| (map, x) |])

The map will be a NameG, and x wil be a NameL

These Names should never appear in a binding position in a TH syntax tree

Constructors

Instances

mkName :: String -> Name Source

The string can have a . , thus Foo.baz, giving a dynamically-bound qualified name, in which case we want to generate a NameQ

Parse the string to see if it has a . in it so we know whether to generate a qualified or unqualified name It's a bit tricky because we need to parse

 Foo.Baz.x as Qual Foo.Baz x

So we parse it from back to front

newName :: String -> Q Name Source

nameBase :: Name -> String Source

Base, unqualified name.

nameModule :: Name -> Maybe String Source

showName :: Name -> String Source

showName' :: NameIs -> Name -> String Source

data NameIs Source

Constructors

The algebraic data types

data Dec Source

Constructors

FunD Name [Clause]
{ f p1 p2 = b where decs }
ValD Pat Body [Dec]
{ p = b where decs }
DataD Cxt Name [TyVarBndr] [Con] [Name]
{ data Cxt x => T x = A x | B (T x)
 deriving (Z,W)}
NewtypeD Cxt Name [TyVarBndr] Con [Name]
{ newtype Cxt x => T x = A (B x)
 deriving (Z,W)}
TySynD Name [TyVarBndr] Type
{ type T x = (x,x) }
ClassD Cxt Name [TyVarBndr] [FunDep] [Dec]
{ class Eq a => Ord a where ds }
InstanceD Cxt Type [Dec]
{ instance Show w => Show [w]
 where ds }
SigD Name Type
{ length :: [a] -> Int }
PragmaD Pragma
{ {--} }
FamilyD FamFlavour Name [TyVarBndr] (Maybe Kind)
{ type family T a b c :: * }
DataInstD Cxt Name [Type] [Con] [Name]
{ data instance Cxt x => T [x] = A x 
 | B (T x)
 deriving (Z,W)}
NewtypeInstD Cxt Name [Type] Con [Name]
{ newtype instance Cxt x => T [x] = A (B x)
 deriving (Z,W)}
TySynInstD Name [Type] Type
{ type instance T (Maybe x) = (x,x) }

Instances

data Exp Source

The CompE constructor represents a list comprehension, and takes a [Stmt ]. The result expression of the comprehension is the *last* of these, and should be a NoBindS .

E.g. translation:

 [ f x | x <- xs ]
 CompE [BindS (VarP x) (VarE xs), NoBindS (AppE (VarE f) (VarE x))]

Constructors

VarE Name
{ x }
ConE Name
data T1 = C1 t1 t2; p = {C1} e1 e2
LitE Lit
{ 5 or c}
AppE Exp Exp
{ f x }
InfixE (Maybe Exp) Exp (Maybe Exp)
{x + y} or {(x+)} or {(+ x)} or {(+)}

It's a bit gruesome to use an Exp as the operator, but how else can we distinguish constructors from non-constructors? Maybe there should be a var-or-con type? Or maybe we should leave it to the String itself?

LamE [Pat] Exp
{ p1 p2 -> e }
TupE [Exp]
{ (e1,e2) }
CondE Exp Exp Exp
{ if e1 then e2 else e3 }
LetE [Dec] Exp
{ let x=e1; y=e2 in e3 }
CaseE Exp [Match]
{ case e of m1; m2 }
DoE [Stmt]
{ do { p <- e1; e2 } }
CompE [Stmt]
{ [ (x,y) | x <- xs, y <- ys ] }
ArithSeqE Range
{ [ 1 ,2 .. 10 ] }
ListE [Exp]
{ [1,2,3] }
SigE Exp Type
{ e :: t }
RecConE Name [FieldExp]
{ T { x = y, z = w } }
RecUpdE Exp [FieldExp]
{ (f x) { z = w } }

Instances

data Con Source

Constructors

RecC Name [VarStrictType]
C { v :: Int, w :: a }
ForallC [TyVarBndr] Cxt Con
forall a. Eq a => C [a]

Instances

data Type Source

Constructors

TupleT Int
(,), (,,), etc.
ArrowT
->
ListT
[]
AppT Type Type
T a b
SigT Type Kind
t :: k

Instances

data TyVarBndr Source

Constructors

KindedTV Name Kind
(a :: k)

Instances

data Kind Source

Constructors

ArrowK Kind Kind
k1 -> k2

Instances

type Cxt Source

Arguments

= [Pred]
(Eq a, Ord b)

data Pred Source

Constructors

ClassP Name [Type]
Eq (Int, a)
EqualP Type Type
F a ~ Bool

Instances

data Match Source

Constructors

Match Pat Body [Dec]
case e of { pat -> body where decs }

Instances

data Clause Source

Constructors

Clause [Pat] Body [Dec]
f { p1 p2 = body where decs }

Instances

data Body Source

Constructors

GuardedB [(Guard, Exp)]
f p { | e1 = e2 | e3 = e4 } where ds
NormalB Exp
f p { = e } where ds

Instances

data Guard Source

Constructors

Instances

data Stmt Source

Constructors

LetS [Dec]
ParS [[Stmt]]

Instances

data Range Source

Constructors

Instances

data Lit Source

Constructors

IntegerL Integer

Used for overloaded and non-overloaded literals. We don't have a good way to represent non-overloaded literals at the moment. Maybe that doesn't matter?

StringPrimL String

A primitive C-style string, type Addr#

Instances

data Pat Source

Pattern in Haskell given in {}

Constructors

LitP Lit
{ 5 or c }
VarP Name
{ x }
TupP [Pat]
{ (p1,p2) }
ConP Name [Pat]
data T1 = C1 t1 t2; {C1 p1 p1} = e
InfixP Pat Name Pat
foo ({x :+ y}) = e
TildeP Pat
{ ~p }
BangP Pat
{ !p }
AsP Name Pat
{ x @ p }
WildP
{ _ }
RecP Name [FieldPat]
f (Pt { pointx = x }) = g x
ListP [Pat]
{ [1,2,3] }
SigP Pat Type
{ p :: t }
ViewP Exp Pat
{ e -> p }

Instances

type FieldExp = (Name, Exp)Source

type FieldPat = (Name, Pat)Source

data ClassInstance Source

ClassInstance desribes a single instance of a class

Constructors

Instances

data Strict Source

Constructors

Instances

data Foreign Source

Constructors

Instances

data Callconv Source

Constructors

Instances

data Safety Source

Constructors

Instances

data Pragma Source

Constructors

Instances

data InlineSpec Source

Constructors

Instances

type StrictType = (Strict, Type)Source

type VarStrictType = (Name, Strict, Type)Source

data FunDep Source

Constructors

Instances

data FamFlavour Source

Constructors

Instances

data Info Source

Obtained from reify in the Q Monad.

Constructors

ClassI Dec [ClassInstance]

A class is reified to its declaration and a list of its instances

Instances

data Loc Source

Constructors

Loc

type CharPos = (Int, Int)Source

data Fixity Source

Constructors

Instances

data FixityDirection Source

Constructors

Instances

defaultFixity :: Fixity Source

maxPrecedence :: Int Source

Internal functions

returnQ :: a -> Q aSource

bindQ :: Q a -> (a -> Q b) -> Q bSource

sequenceQ :: [Q a] -> Q [a]Source

data NameFlavour Source

Constructors

NameS

An unqualified name; dynamically bound

NameQ ModName

A qualified name; dynamically bound

NameU Int#

A unique local name

NameL Int#

Local name bound outside of the TH AST

NameG NameSpace PkgName ModName

Global name bound outside of the TH AST: An original name (occurrences only, not binders)

Need the namespace too to be sure which thing we are naming

Instances

Data NameFlavour

Although the NameFlavour type is abstract, the Data instance is not. The reason for this is that currently we use Data to serialize values in annotations, and in order for that to work for Template Haskell names introduced via the 'x syntax we need gunfold on NameFlavour to work. Bleh!

The long term solution to this is to use the binary package for annotation serialization and then remove this instance. However, to do _that_ we need to wait on binary to become stable, since boot libraries cannot be upgraded seperately from GHC itself.

This instance cannot be derived automatically due to bug #2701

data NameSpace Source

Constructors

VarName

Variables

DataName

Data constructors

TcClsName

Type constructors and classes; Haskell has them in the same name space for now.

Instances

mkNameG_v :: String -> String -> String -> Name Source

mkNameG_d :: String -> String -> String -> Name Source

mkNameG_tc :: String -> String -> String -> Name Source

type Uniq = Int Source

mkNameL :: String -> Uniq -> Name Source

Only used internally

mkNameU :: String -> Uniq -> Name Source

Only used internally

tupleTypeName Source

Arguments

:: Int
-> Name

Type constructor

tupleDataName Source

Arguments

:: Int
-> Name

Data constructor

data OccName Source

Instances

mkOccName :: String -> OccName Source

occString :: OccName -> String Source

data ModName Source

Instances

mkModName :: String -> ModName Source

modString :: ModName -> String Source

data PkgName Source

Instances

mkPkgName :: String -> PkgName Source

pkgString :: PkgName -> String Source

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