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 ---------------- ------------- GhcPsRdrName parserRdrHsSyn GhcRnName renameRnHsSyn GhcTcId typecheckTcHsSyn

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)

mkHsAppType :: NoGhcTc (GhcPass id) ~ GhcRn => LHsExpr (GhcPass id) -> LHsWcType GhcRn -> LHsExpr (GhcPass id)

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 (NameOrRdrName (IdP (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 :: HsMatchContext (NameOrRdrName (IdP (GhcPass p))) -> [LPat (GhcPass p)] -> LHsExpr (GhcPass p) -> Located (HsLocalBinds (GhcPass p)) -> LMatch (GhcPass p) (LHsExpr (GhcPass p))

mkPrefixFunRhs :: Located id -> HsMatchContext id

Make a prefix, non-strict function HsMatchContext

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

mkHsIf :: LHsExpr (GhcPass p) -> LHsExpr (GhcPass p) -> LHsExpr (GhcPass p) -> HsExpr (GhcPass p)

mkHsWrap :: HsWrapper -> HsExpr (GhcPass id) -> HsExpr (GhcPass id)

Avoid (HsWrap co (HsWrap co' _)). See Note [Detecting forced eta expansion] in DsExpr

mkLHsWrap :: HsWrapper -> LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)

mkHsWrapCo :: TcCoercionN -> HsExpr (GhcPass id) -> HsExpr (GhcPass id)

mkHsWrapCoR :: TcCoercionR -> HsExpr (GhcPass id) -> HsExpr (GhcPass id)

mkLHsWrapCo :: TcCoercionN -> LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)

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 Name -> [ExprLStmt GhcPs] -> HsExpr GhcPs

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

mkHsWrapPat :: HsWrapper -> Pat (GhcPass id) -> Type -> Pat (GhcPass id)

mkHsWrapPatCo :: TcCoercionN -> Pat (GhcPass id) -> Type -> Pat (GhcPass id)

mkLHsPar :: 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 (GhcPass p) -> HsCmd (GhcPass p)

mkLHsCmdWrap :: HsWrapper -> LHsCmd (GhcPass p) -> LHsCmd (GhcPass p)

mkHsCmdIf :: LHsExpr (GhcPass p) -> LHsCmd (GhcPass p) -> LHsCmd (GhcPass p) -> HsCmd (GhcPass p)

nlHsTyApp :: IdP (GhcPass id) -> [Type] -> LHsExpr (GhcPass id)

nlHsTyApps :: IdP (GhcPass id) -> [Type] -> [LHsExpr (GhcPass id)] -> LHsExpr (GhcPass id)

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

nlHsDataCon :: DataCon -> LHsExpr GhcTc

NB: Only for LHsExpr **Id**

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

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

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

nlHsSyntaxApps :: SyntaxExpr (GhcPass id) -> [LHsExpr (GhcPass id)] -> LHsExpr (GhcPass id)

nlHsIntLit :: Integer -> LHsExpr (GhcPass p)

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

nlHsDo :: HsStmtContext Name -> [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 (GhcPass id) -> LHsExpr (GhcPass id) -> LHsExpr (GhcPass id) -> LHsExpr (GhcPass id)

Note [Rebindable nlHsIf] nlHsIf should generate if-expressions which are NOT subject to RebindableSyntax, so the first field of HsIf is Nothing. (#12080)

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

typeToLHsType :: Type -> LHsType GhcPs

Converting a Type to an HsType RdrName This is needed to implement GeneralizedNewtypeDeriving.

Note that we use getRdrName extensively, which generates Exact RdrNames rather than strings.

Constructing general big tuples

GHCs built in tuples can only go up to mAX_TUPLE_SIZE in arity, but we might concievably 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 decompositon

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 :: IdP (GhcPass p) -> LPat (GhcPass p)

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

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

mkBindStmt :: XBindStmt (GhcPass idL) (GhcPass idR) (Located (bodyR (GhcPass idR))) ~ NoExtField => LPat (GhcPass idL) -> Located (bodyR (GhcPass idR)) -> StmtLR (GhcPass idL) (GhcPass idR) (Located (bodyR (GhcPass idR)))

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

mkLastStmt :: 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

unqualQuasiQuote :: RdrName

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 DsBinds.

isBangedHsBind :: HsBind GhcTc -> Bool

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

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

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

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

collectHsBindListBinders :: [LHsBindLR (GhcPass p) idR] -> [IdP (GhcPass p)]

Same as collectHsBindsBinders, but works over a list of bindings

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

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

collectHsBindsBinders :: LHsBindsLR (GhcPass p) idR -> [IdP (GhcPass p)]

collectHsBindBinders :: (SrcSpanLess (LPat p) ~ Pat p, HasSrcSpan (LPat 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 :: LPat (GhcPass p) -> [IdP (GhcPass p)]

collectPatsBinders :: [LPat (GhcPass p)] -> [IdP (GhcPass p)]

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

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

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

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

hsLTyClDeclBinders :: 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 :: 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])]