GHC.Hs.Utils

Here we collect a variety of helper functions that construct or analyse HsSyn. All these functions deal with generic HsSyn; functions which deal with the instantiated versions are located elsewhere:

Parameterised by Module ---------------- ------------- GhcPs/RdrName GHC.Parser.PostProcess GhcRn/Name GHC.Rename.* GhcTc/Id GHC.Tc.Utils.Zonk

The mk* functions attempt to construct a not-completely-useless SrcSpan from their components, compared with the nl* functions which just attach noSrcSpan to everything.

Terms

mkHsPar :: LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)

e => (e)

mkHsApp :: LHsExpr (GhcPass id) -> LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)

mkHsAppWith :: (LHsExpr (GhcPass id) -> LHsExpr (GhcPass id) -> HsExpr (GhcPass id) -> LHsExpr (GhcPass id)) -> LHsExpr (GhcPass id) -> LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)

mkHsApps :: LHsExpr (GhcPass id) -> [LHsExpr (GhcPass id)] -> LHsExpr (GhcPass id)

mkHsAppsWith :: (LHsExpr (GhcPass id) -> LHsExpr (GhcPass id) -> HsExpr (GhcPass id) -> LHsExpr (GhcPass id)) -> LHsExpr (GhcPass id) -> [LHsExpr (GhcPass id)] -> LHsExpr (GhcPass id)

mkHsAppType :: LHsExpr GhcRn -> LHsWcType GhcRn -> LHsExpr GhcRn

mkHsAppTypes :: LHsExpr GhcRn -> [LHsWcType GhcRn] -> LHsExpr GhcRn

mkHsCaseAlt :: LPat (GhcPass p) -> Located (body (GhcPass p)) -> LMatch (GhcPass p) (Located (body (GhcPass p)))

A simple case alternative with a single pattern, no binds, no guards; pre-typechecking

mkSimpleMatch :: HsMatchContext (NoGhcTc (GhcPass p)) -> [LPat (GhcPass p)] -> Located (body (GhcPass p)) -> LMatch (GhcPass p) (Located (body (GhcPass p)))

unguardedGRHSs :: Located (body (GhcPass p)) -> GRHSs (GhcPass p) (Located (body (GhcPass p)))

unguardedRHS :: SrcSpan -> Located (body (GhcPass p)) -> [LGRHS (GhcPass p) (Located (body (GhcPass p)))]

mkMatchGroup :: XMG name (Located (body name)) ~ NoExtField => Origin -> [LMatch name (Located (body name))] -> MatchGroup name (Located (body name))

mkMatch :: forall p. IsPass p => HsMatchContext (NoGhcTc (GhcPass p)) -> [LPat (GhcPass p)] -> LHsExpr (GhcPass p) -> Located (HsLocalBinds (GhcPass p)) -> LMatch (GhcPass p) (LHsExpr (GhcPass p))

mkPrefixFunRhs :: LIdP p -> HsMatchContext p

Make a prefix, non-strict function HsMatchContext

mkHsLam :: IsPass p => XMG (GhcPass p) (LHsExpr (GhcPass p)) ~ NoExtField => [LPat (GhcPass p)] -> LHsExpr (GhcPass p) -> LHsExpr (GhcPass p)

mkHsIf :: LHsExpr GhcPs -> LHsExpr GhcPs -> LHsExpr GhcPs -> HsExpr GhcPs

mkHsWrap :: HsWrapper -> HsExpr GhcTc -> HsExpr GhcTc

Avoid HsWrap co1 (HsWrap co2 _) and HsWrap co1 (HsPar _ _) See Note [Detecting forced eta expansion] in GHC.HsToCore.Expr

mkLHsWrap :: HsWrapper -> LHsExpr GhcTc -> LHsExpr GhcTc

mkHsWrapCo :: TcCoercionN -> HsExpr GhcTc -> HsExpr GhcTc

mkHsWrapCoR :: TcCoercionR -> HsExpr GhcTc -> HsExpr GhcTc

mkLHsWrapCo :: TcCoercionN -> LHsExpr GhcTc -> LHsExpr GhcTc

mkHsDictLet :: TcEvBinds -> LHsExpr GhcTc -> LHsExpr GhcTc

mkHsLams :: [TyVar] -> [EvVar] -> LHsExpr GhcTc -> LHsExpr GhcTc

mkHsOpApp :: LHsExpr GhcPs -> IdP GhcPs -> LHsExpr GhcPs -> HsExpr GhcPs

A useful function for building OpApps. The operator is always a variable, and we don't know the fixity yet.

mkHsDo :: HsStmtContext GhcRn -> [ExprLStmt GhcPs] -> HsExpr GhcPs

mkHsComp :: HsStmtContext GhcRn -> [ExprLStmt GhcPs] -> LHsExpr GhcPs -> HsExpr GhcPs

mkHsWrapPat :: HsWrapper -> Pat GhcTc -> Type -> Pat GhcTc

mkHsWrapPatCo :: TcCoercionN -> Pat GhcTc -> Type -> Pat GhcTc

mkLHsPar :: IsPass id => LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)

Wrap in parens if hsExprNeedsParens appPrec says it needs them So f x becomes (f x), but 3 stays as 3.

mkHsCmdWrap :: HsWrapper -> HsCmd GhcTc -> HsCmd GhcTc

mkLHsCmdWrap :: HsWrapper -> LHsCmd GhcTc -> LHsCmd GhcTc

mkHsCmdIf :: LHsExpr GhcPs -> LHsCmd GhcPs -> LHsCmd GhcPs -> HsCmd GhcPs

nlHsTyApp :: Id -> [Type] -> LHsExpr GhcTc

nlHsTyApps :: Id -> [Type] -> [LHsExpr GhcTc] -> LHsExpr GhcTc

nlHsVar :: IdP (GhcPass id) -> LHsExpr (GhcPass id)

nl_HsVar :: IdP (GhcPass id) -> HsExpr (GhcPass id)

nlHsDataCon :: DataCon -> LHsExpr GhcTc

NB: Only for LHsExpr Id.

nlHsLit :: HsLit (GhcPass p) -> LHsExpr (GhcPass p)

nlHsApp :: IsPass id => LHsExpr (GhcPass id) -> LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)

nlHsApps :: IsPass id => IdP (GhcPass id) -> [LHsExpr (GhcPass id)] -> LHsExpr (GhcPass id)

nlHsSyntaxApps :: SyntaxExprTc -> [LHsExpr GhcTc] -> LHsExpr GhcTc

nlHsIntLit :: Integer -> LHsExpr (GhcPass p)

nlHsVarApps :: IdP (GhcPass id) -> [IdP (GhcPass id)] -> LHsExpr (GhcPass id)

nlHsDo :: HsStmtContext GhcRn -> [LStmt GhcPs (LHsExpr GhcPs)] -> LHsExpr GhcPs

nlHsOpApp :: LHsExpr GhcPs -> IdP GhcPs -> LHsExpr GhcPs -> LHsExpr GhcPs

nlHsLam :: LMatch GhcPs (LHsExpr GhcPs) -> LHsExpr GhcPs

nlHsPar :: LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)

nlHsIf :: LHsExpr GhcPs -> LHsExpr GhcPs -> LHsExpr GhcPs -> LHsExpr GhcPs

nlHsCase :: LHsExpr GhcPs -> [LMatch GhcPs (LHsExpr GhcPs)] -> LHsExpr GhcPs

nlList :: [LHsExpr GhcPs] -> LHsExpr GhcPs

mkLHsTupleExpr :: [LHsExpr (GhcPass a)] -> LHsExpr (GhcPass a)

mkLHsVarTuple :: [IdP (GhcPass a)] -> LHsExpr (GhcPass a)

missingTupArg :: HsTupArg GhcPs

Constructing general big tuples

GHCs built in tuples can only go up to mAX_TUPLE_SIZE in arity, but we might conceivably want to build such a massive tuple as part of the output of a desugaring stage (notably that for list comprehensions).

We call tuples above this size "big tuples", and emulate them by creating and pattern matching on >nested< tuples that are expressible by GHC.

Nesting policy: it's better to have a 2-tuple of 10-tuples (3 objects) than a 10-tuple of 2-tuples (11 objects), so we want the leaves of any construction to be big.

If you just use the mkBigCoreTup, mkBigCoreVarTupTy, mkTupleSelector and mkTupleCase functions to do all your work with tuples you should be fine, and not have to worry about the arity limitation at all.

mkChunkified

Arguments

:: ([a] -> a)

"Small" constructor function, of maximum input arity mAX_TUPLE_SIZE

-> [a]

Possible "big" list of things to construct from

-> a

Constructed thing made possible by recursive decomposition

Lifts a "small" constructor into a "big" constructor by recursive decomposition

chunkify :: [a] -> [[a]]

Split a list into lists that are small enough to have a corresponding tuple arity. The sub-lists of the result all have length <= mAX_TUPLE_SIZE But there may be more than mAX_TUPLE_SIZE sub-lists

Bindings

mkFunBind :: Origin -> Located RdrName -> [LMatch GhcPs (LHsExpr GhcPs)] -> HsBind GhcPs

Not infix, with place holders for coercion and free vars

mkVarBind :: IdP (GhcPass p) -> LHsExpr (GhcPass p) -> LHsBind (GhcPass p)

mkHsVarBind :: SrcSpan -> RdrName -> LHsExpr GhcPs -> LHsBind GhcPs

mkSimpleGeneratedFunBind :: SrcSpan -> RdrName -> [LPat GhcPs] -> LHsExpr GhcPs -> LHsBind GhcPs

Convenience function using mkFunBind. This is for generated bindings only, do not use for user-written code.

mkTopFunBind :: Origin -> Located Name -> [LMatch GhcRn (LHsExpr GhcRn)] -> HsBind GhcRn

In Name-land, with empty bind_fvs

mkPatSynBind :: Located RdrName -> HsPatSynDetails (Located RdrName) -> LPat GhcPs -> HsPatSynDir GhcPs -> HsBind GhcPs

isInfixFunBind :: HsBindLR id1 id2 -> Bool

If any of the matches in the FunBind are infix, the FunBind is considered infix.

Literals

mkHsIntegral :: IntegralLit -> HsOverLit GhcPs

mkHsFractional :: FractionalLit -> HsOverLit GhcPs

mkHsIsString :: SourceText -> FastString -> HsOverLit GhcPs

mkHsString :: String -> HsLit (GhcPass p)

mkHsStringPrimLit :: FastString -> HsLit (GhcPass p)

Patterns

mkNPat :: Located (HsOverLit GhcPs) -> Maybe (SyntaxExpr GhcPs) -> Pat GhcPs

mkNPlusKPat :: Located RdrName -> Located (HsOverLit GhcPs) -> Pat GhcPs

nlVarPat :: IdP (GhcPass id) -> LPat (GhcPass id)

nlLitPat :: HsLit GhcPs -> LPat GhcPs

nlConVarPat :: RdrName -> [RdrName] -> LPat GhcPs

nlConVarPatName :: Name -> [Name] -> LPat GhcRn

nlConPat :: RdrName -> [LPat GhcPs] -> LPat GhcPs

nlConPatName :: Name -> [LPat GhcRn] -> LPat GhcRn

nlInfixConPat :: RdrName -> LPat GhcPs -> LPat GhcPs -> LPat GhcPs

nlNullaryConPat :: RdrName -> LPat GhcPs

nlWildConPat :: DataCon -> LPat GhcPs

nlWildPat :: LPat GhcPs

Wildcard pattern - after parsing

nlWildPatName :: LPat GhcRn

Wildcard pattern - after renaming

nlTuplePat :: [LPat GhcPs] -> Boxity -> LPat GhcPs

mkParPat :: IsPass p => LPat (GhcPass p) -> LPat (GhcPass p)

nlParPat :: LPat (GhcPass name) -> LPat (GhcPass name)

mkBigLHsVarTup :: [IdP (GhcPass id)] -> LHsExpr (GhcPass id)

The Big equivalents for the source tuple expressions

mkBigLHsTup :: [LHsExpr (GhcPass id)] -> LHsExpr (GhcPass id)

mkBigLHsVarPatTup :: [IdP GhcRn] -> LPat GhcRn

The Big equivalents for the source tuple patterns

mkBigLHsPatTup :: [LPat GhcRn] -> LPat GhcRn

Types

mkHsAppTy :: LHsType (GhcPass p) -> LHsType (GhcPass p) -> LHsType (GhcPass p)

mkHsAppKindTy :: XAppKindTy (GhcPass p) -> LHsType (GhcPass p) -> LHsType (GhcPass p) -> LHsType (GhcPass p)

mkLHsSigType :: LHsType GhcPs -> LHsSigType GhcPs

mkLHsSigWcType :: LHsType GhcPs -> LHsSigWcType GhcPs

mkClassOpSigs :: [LSig GhcPs] -> [LSig GhcPs]

Convert TypeSig to ClassOpSig. The former is what is parsed, but the latter is what we need in class/instance declarations

mkHsSigEnv :: forall a. (LSig GhcRn -> Maybe ([Located Name], a)) -> [LSig GhcRn] -> NameEnv a

nlHsAppTy :: LHsType (GhcPass p) -> LHsType (GhcPass p) -> LHsType (GhcPass p)

nlHsAppKindTy :: LHsType (GhcPass p) -> LHsKind (GhcPass p) -> LHsType (GhcPass p)

nlHsTyVar :: IdP (GhcPass p) -> LHsType (GhcPass p)

nlHsFunTy :: LHsType (GhcPass p) -> LHsType (GhcPass p) -> LHsType (GhcPass p)

nlHsParTy :: LHsType (GhcPass p) -> LHsType (GhcPass p)

nlHsTyConApp :: LexicalFixity -> IdP (GhcPass p) -> [LHsTypeArg (GhcPass p)] -> LHsType (GhcPass p)

Stmts

mkTransformStmt :: [ExprLStmt GhcPs] -> LHsExpr GhcPs -> StmtLR GhcPs GhcPs (LHsExpr GhcPs)

mkTransformByStmt :: [ExprLStmt GhcPs] -> LHsExpr GhcPs -> LHsExpr GhcPs -> StmtLR GhcPs GhcPs (LHsExpr GhcPs)

mkBodyStmt :: Located (bodyR GhcPs) -> StmtLR (GhcPass idL) GhcPs (Located (bodyR GhcPs))

mkPsBindStmt :: LPat GhcPs -> Located (bodyR GhcPs) -> StmtLR GhcPs GhcPs (Located (bodyR GhcPs))

mkRnBindStmt :: LPat GhcRn -> Located (bodyR GhcRn) -> StmtLR GhcRn GhcRn (Located (bodyR GhcRn))

mkTcBindStmt :: LPat GhcTc -> Located (bodyR GhcTc) -> StmtLR GhcTc GhcTc (Located (bodyR GhcTc))

mkLastStmt :: IsPass idR => Located (bodyR (GhcPass idR)) -> StmtLR (GhcPass idL) (GhcPass idR) (Located (bodyR (GhcPass idR)))

emptyTransStmt :: StmtLR GhcPs GhcPs (LHsExpr GhcPs)

mkGroupUsingStmt :: [ExprLStmt GhcPs] -> LHsExpr GhcPs -> StmtLR GhcPs GhcPs (LHsExpr GhcPs)

mkGroupByUsingStmt :: [ExprLStmt GhcPs] -> LHsExpr GhcPs -> LHsExpr GhcPs -> StmtLR GhcPs GhcPs (LHsExpr GhcPs)

emptyRecStmt :: StmtLR (GhcPass idL) GhcPs bodyR

emptyRecStmtName :: StmtLR GhcRn GhcRn bodyR

emptyRecStmtId :: StmtLR GhcTc GhcTc bodyR

mkRecStmt :: [LStmtLR (GhcPass idL) GhcPs bodyR] -> StmtLR (GhcPass idL) GhcPs bodyR

unitRecStmtTc :: RecStmtTc

Template Haskell

mkUntypedSplice :: SpliceDecoration -> LHsExpr GhcPs -> HsSplice GhcPs

mkTypedSplice :: SpliceDecoration -> LHsExpr GhcPs -> HsSplice GhcPs

mkHsQuasiQuote :: RdrName -> SrcSpan -> FastString -> HsSplice GhcPs

Collecting binders

isUnliftedHsBind :: HsBind GhcTc -> Bool

Should we treat this as an unlifted bind? This will be true for any bind that binds an unlifted variable, but we must be careful around AbsBinds. See Note [Unlifted id check in isUnliftedHsBind]. For usage information, see Note [Strict binds check] is GHC.HsToCore.Binds.

isBangedHsBind :: HsBind GhcTc -> Bool

Is a binding a strict variable or pattern bind (e.g. !x = ...)?

collectLocalBinders :: CollectPass (GhcPass idL) => HsLocalBindsLR (GhcPass idL) (GhcPass idR) -> [IdP (GhcPass idL)]

collectHsValBinders :: CollectPass (GhcPass idL) => HsValBindsLR (GhcPass idL) (GhcPass idR) -> [IdP (GhcPass idL)]

collectHsBindListBinders :: CollectPass p => [LHsBindLR p idR] -> [IdP p]

Same as collectHsBindsBinders, but works over a list of bindings

collectHsIdBinders :: CollectPass (GhcPass idL) => HsValBindsLR (GhcPass idL) (GhcPass idR) -> [IdP (GhcPass idL)]

Collect Id binders only, or Ids + pattern synonyms, respectively

collectHsBindsBinders :: CollectPass p => LHsBindsLR p idR -> [IdP p]

collectHsBindBinders :: CollectPass p => HsBindLR p idR -> [IdP p]

Collect both Ids and pattern-synonym binders

collectMethodBinders :: LHsBindsLR idL idR -> [Located (IdP idL)]

Used exclusively for the bindings of an instance decl which are all FunBinds

collectPatBinders :: CollectPass p => LPat p -> [IdP p]

collectPatsBinders :: CollectPass p => [LPat p] -> [IdP p]

collectLStmtsBinders :: CollectPass (GhcPass idL) => [LStmtLR (GhcPass idL) (GhcPass idR) body] -> [IdP (GhcPass idL)]

collectStmtsBinders :: CollectPass (GhcPass idL) => [StmtLR (GhcPass idL) (GhcPass idR) body] -> [IdP (GhcPass idL)]

collectLStmtBinders :: CollectPass (GhcPass idL) => LStmtLR (GhcPass idL) (GhcPass idR) body -> [IdP (GhcPass idL)]

collectStmtBinders :: CollectPass (GhcPass idL) => StmtLR (GhcPass idL) (GhcPass idR) body -> [IdP (GhcPass idL)]

class XRec p Pat ~ Located (Pat p) => CollectPass p where

This class specifies how to collect variable identifiers from extension patterns in the given pass. Consumers of the GHC API that define their own passes should feel free to implement instances in order to make use of functions which depend on it.

In particular, Haddock already makes use of this, with an instance for its DocNameI pass so that it can reuse the code in GHC for collecting binders.

Methods

collectXXPat :: Proxy p -> XXPat p -> [IdP p] -> [IdP p]

Instances

CollectPass (GhcPass 'Parsed)

Defined in GHC.Hs.Utils

Methods

collectXXPat :: Proxy (GhcPass 'Parsed) -> XXPat (GhcPass 'Parsed) -> [IdP (GhcPass 'Parsed)] -> [IdP (GhcPass 'Parsed)]

CollectPass (GhcPass 'Renamed)

Defined in GHC.Hs.Utils

Methods

collectXXPat :: Proxy (GhcPass 'Renamed) -> XXPat (GhcPass 'Renamed) -> [IdP (GhcPass 'Renamed)] -> [IdP (GhcPass 'Renamed)]

CollectPass (GhcPass 'Typechecked)

Defined in GHC.Hs.Utils

Methods

collectXXPat :: Proxy (GhcPass 'Typechecked) -> XXPat (GhcPass 'Typechecked) -> [IdP (GhcPass 'Typechecked)] -> [IdP (GhcPass 'Typechecked)]

hsLTyClDeclBinders :: IsPass p => Located (TyClDecl (GhcPass p)) -> ([Located (IdP (GhcPass p))], [LFieldOcc (GhcPass p)])

Returns all the binding names of the decl. The first one is guaranteed to be the name of the decl. The first component represents all binding names except record fields; the second represents field occurrences. For record fields mentioned in multiple constructors, the SrcLoc will be from the first occurrence.

Each returned (Located name) has a SrcSpan for the whole declaration. See Note [SrcSpan for binders]

hsTyClForeignBinders :: [TyClGroup GhcRn] -> [LForeignDecl GhcRn] -> [Name]

hsPatSynSelectors :: HsValBinds (GhcPass p) -> [IdP (GhcPass p)]

Collects record pattern-synonym selectors only; the pattern synonym names are collected by collectHsValBinders.

getPatSynBinds :: [(RecFlag, LHsBinds id)] -> [PatSynBind id id]

hsForeignDeclsBinders :: [LForeignDecl pass] -> [Located (IdP pass)]

See Note [SrcSpan for binders]

hsGroupBinders :: HsGroup GhcRn -> [Name]

hsDataFamInstBinders :: IsPass p => DataFamInstDecl (GhcPass p) -> ([Located (IdP (GhcPass p))], [LFieldOcc (GhcPass p)])

the SrcLoc returned are for the whole declarations, not just the names

Collecting implicit binders

lStmtsImplicits :: [LStmtLR GhcRn (GhcPass idR) (Located (body (GhcPass idR)))] -> [(SrcSpan, [Name])]

hsValBindsImplicits :: HsValBindsLR GhcRn (GhcPass idR) -> [(SrcSpan, [Name])]

lPatImplicits :: LPat GhcRn -> [(SrcSpan, [Name])]