ghc-7.0.1: The GHC API




Abstract Haskell syntax for expressions.


Expressions proper

type PostTcExpr = HsExpr IdSource

PostTcExpr is an evidence expression attached to the syntax tree by the type checker (c.f. postTcType).

type PostTcTable = [(Name, PostTcExpr)]Source

We use a PostTcTable where there are a bunch of pieces of evidence, more than is convenient to keep individually.

type SyntaxExpr id = HsExpr idSource

SyntaxExpr is like PostTcExpr, but it's filled in a little earlier, by the renamer. It's used for rebindable syntax.

E.g. (>>=) is filled in before the renamer by the appropriate Name for (>>=), and then instantiated by the type checker with its type args etc

type SyntaxTable id = [(Name, SyntaxExpr id)]Source

Currently used only for CmdTop (sigh)

  • Before the renamer, this list is noSyntaxTable
  • After the renamer, it takes the form [(std_name, HsVar actual_name)] For example, for the return op of a monad
  • normal case: (GHC.Base.return, HsVar GHC.Base.return)
  • with rebindable syntax: (GHC.Base.return, return_22) where return_22 is whatever return is in scope
  • After the type checker, it takes the form [(std_name, expression)] where expression is the evidence for the method

data HsExpr id Source

A Haskell expression.


HsVar id


HsIPVar (IPName id)

implicit parameter

HsOverLit (HsOverLit id)

Overloaded literals

HsLit HsLit

Simple (non-overloaded) literals

HsLam (MatchGroup id) 
HsApp (LHsExpr id) (LHsExpr id) 
OpApp (LHsExpr id) (LHsExpr id) Fixity (LHsExpr id) 
NegApp (LHsExpr id) (SyntaxExpr id) 
HsPar (LHsExpr id) 
SectionL (LHsExpr id) (LHsExpr id) 
SectionR (LHsExpr id) (LHsExpr id) 
ExplicitTuple [HsTupArg id] Boxity 
HsCase (LHsExpr id) (MatchGroup id) 
HsIf (Maybe (SyntaxExpr id)) (LHsExpr id) (LHsExpr id) (LHsExpr id) 
HsLet (HsLocalBinds id) (LHsExpr id) 
HsDo (HsStmtContext Name) [LStmt id] (LHsExpr id) PostTcType 
ExplicitList PostTcType [LHsExpr id] 
ExplicitPArr PostTcType [LHsExpr id] 
RecordCon (Located id) PostTcExpr (HsRecordBinds id) 
RecordUpd (LHsExpr id) (HsRecordBinds id) [DataCon] [PostTcType] [PostTcType] 
ExprWithTySig (LHsExpr id) (LHsType id) 
ExprWithTySigOut (LHsExpr id) (LHsType Name) 
ArithSeq PostTcExpr (ArithSeqInfo id) 
PArrSeq PostTcExpr (ArithSeqInfo id) 
HsSCC FastString (LHsExpr id) 
HsCoreAnn FastString (LHsExpr id) 
HsBracket (HsBracket id) 
HsBracketOut (HsBracket Name) [PendingSplice] 
HsSpliceE (HsSplice id) 
HsQuasiQuoteE (HsQuasiQuote id) 
HsProc (LPat id) (LHsCmdTop id) 
HsArrApp (LHsExpr id) (LHsExpr id) PostTcType HsArrAppType Bool 
HsArrForm (LHsExpr id) (Maybe Fixity) [LHsCmdTop id] 
HsTick Int [id] (LHsExpr id) 
HsBinTick Int Int (LHsExpr id) 
HsTickPragma (FastString, (Int, Int), (Int, Int)) (LHsExpr id) 
EAsPat (Located id) (LHsExpr id) 
EViewPat (LHsExpr id) (LHsExpr id) 
ELazyPat (LHsExpr id) 
HsType (LHsType id) 
HsWrap HsWrapper (HsExpr id) 


data HsTupArg id Source


Present (LHsExpr id) 
Missing PostTcType 


type HsCmd id = HsExpr idSource

type LHsCmd id = LHsExpr idSource

data MatchGroup id Source


MatchGroup [LMatch id] PostTcType 


type LMatch id = Located (Match id)Source

data Match id Source


Match [LPat id] (Maybe (LHsType id)) (GRHSs id) 


Typeable1 Match 
Data id => Data (Match id) 

data GRHSs id Source

GRHSs are used both for pattern bindings and for Matches




grhssGRHSs :: [LGRHS id]

Guarded RHSs

grhssLocalBinds :: HsLocalBinds id

The where clause


Typeable1 GRHSs 
Data id => Data (GRHSs id) 

type LGRHS id = Located (GRHS id)Source

data GRHS id Source

Guarded Right Hand Side.


GRHS [LStmt id] (LHsExpr id) 


Typeable1 GRHS 
Data id => Data (GRHS id) 

type LStmt id = Located (StmtLR id id)Source

type LStmtLR idL idR = Located (StmtLR idL idR)Source

type Stmt id = StmtLR id idSource

data StmtLR idL idR Source


BindStmt (LPat idL) (LHsExpr idR) (SyntaxExpr idR) (SyntaxExpr idR) 
ExprStmt (LHsExpr idR) (SyntaxExpr idR) PostTcType 
LetStmt (HsLocalBindsLR idL idR) 
ParStmt [([LStmt idL], [idR])] 
TransformStmt [LStmt idL] [idR] (LHsExpr idR) (Maybe (LHsExpr idR)) 
GroupStmt [LStmt idL] [(idR, idR)] (Maybe (LHsExpr idR)) (Either (LHsExpr idR) (SyntaxExpr idR)) 


Typeable2 StmtLR 
(Data idL, Data idR) => Data (StmtLR idL idR) 
(OutputableBndr idL, OutputableBndr idR) => Outputable (StmtLR idL idR) 

data HsSplice id Source


HsSplice id (LHsExpr id) 

data HsBracket id Source


ExpBr (LHsExpr id) 
PatBr (LPat id) 
DecBrL [LHsDecl id] 
DecBrG (HsGroup id) 
TypBr (LHsType id) 
VarBr id