X-Git-Url: http://git.megacz.com/?p=ghc-hetmet.git;a=blobdiff_plain;f=compiler%2FhsSyn%2FHsExpr.lhs;h=b7fe6fc1331324faab65b036fd36d9d2d5342da8;hp=c3f38cac4bfaf9910887fd49a4df1ab0423841f7;hb=34c8d0312071f7d0f4d221a997d3408c653ef9e5;hpb=f04dead93a15af1cb818172f207b8a81d2c81298 diff --git a/compiler/hsSyn/HsExpr.lhs b/compiler/hsSyn/HsExpr.lhs index c3f38ca..b7fe6fc 100644 --- a/compiler/hsSyn/HsExpr.lhs +++ b/compiler/hsSyn/HsExpr.lhs @@ -3,6 +3,7 @@ % (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \begin{code} +{-# LANGUAGE DeriveDataTypeable #-} -- | Abstract Haskell syntax for expressions. module HsExpr where @@ -24,6 +25,9 @@ import DataCon import SrcLoc import Outputable import FastString + +-- libraries: +import Data.Data hiding (Fixity) \end{code} @@ -44,7 +48,7 @@ type LHsExpr id = Located (HsExpr id) type PostTcExpr = HsExpr Id -- | We use a PostTcTable where there are a bunch of pieces of evidence, more -- than is convenient to keep individually. -type PostTcTable = [(Name, Id)] +type PostTcTable = [(Name, PostTcExpr)] noPostTcExpr :: PostTcExpr noPostTcExpr = HsLit (HsString (fsLit "noPostTcExpr")) @@ -58,7 +62,7 @@ noPostTcTable = [] -- -- E.g. @(>>=)@ is filled in before the renamer by the appropriate 'Name' for -- @(>>=)@, and then instantiated by the type checker with its type args --- tec +-- etc type SyntaxExpr id = HsExpr id @@ -128,7 +132,10 @@ data HsExpr id | HsCase (LHsExpr id) (MatchGroup id) - | HsIf (LHsExpr id) -- predicate + | HsIf (Maybe (SyntaxExpr id)) -- cond function + -- Nothing => use the built-in 'if' + -- See Note [Rebindable if] + (LHsExpr id) -- predicate (LHsExpr id) -- then part (LHsExpr id) -- else part @@ -216,6 +223,13 @@ data HsExpr id (LHsCmdTop id) -- body of the abstraction -- always has an empty stack + ----------------------------------------------------------- + -- Heterogeneous Metaprogramming extension + + | HsHetMetBrak PostTcType (LHsExpr id) -- code type brackets + | HsHetMetEsc PostTcType PostTcType (LHsExpr id) -- code type escape + | HsHetMetCSP PostTcType (LHsExpr id) -- code type cross-stage persistence + --------------------------------------- -- The following are commands, not expressions proper @@ -275,6 +289,7 @@ data HsExpr id | HsWrap HsWrapper -- TRANSLATION (HsExpr id) + deriving (Data, Typeable) -- HsTupArg is used for tuple sections -- (,a,) is represented by ExplicitTuple [Mising ty1, Present a, Missing ty3] @@ -282,6 +297,7 @@ data HsExpr id data HsTupArg id = Present (LHsExpr id) -- The argument | Missing PostTcType -- The argument is missing, but this is its type + deriving (Data, Typeable) tupArgPresent :: HsTupArg id -> Bool tupArgPresent (Present {}) = True @@ -291,11 +307,18 @@ type PendingSplice = (Name, LHsExpr Id) -- Typechecked splices, waiting to be -- pasted back in by the desugarer \end{code} -A @Dictionary@, unless of length 0 or 1, becomes a tuple. A -@ClassDictLam dictvars methods expr@ is, therefore: -\begin{verbatim} -\ x -> case x of ( dictvars-and-methods-tuple ) -> expr -\end{verbatim} +Note [Rebindable if] +~~~~~~~~~~~~~~~~~~~~ +The rebindable syntax for 'if' is a bit special, because when +rebindable syntax is *off* we do not want to treat + (if c then t else e) +as if it was an application (ifThenElse c t e). Why not? +Because we allow an 'if' to return *unboxed* results, thus + if blah then 3# else 4# +whereas that would not be possible using a all to a polymorphic function +(because you can't call a polymorphic function at an unboxed type). + +So we use Nothing to mean "use the old built-in typing rule". \begin{code} instance OutputableBndr id => Outputable (HsExpr id) where @@ -337,6 +360,9 @@ ppr_expr (HsIPVar v) = ppr v ppr_expr (HsLit lit) = ppr lit ppr_expr (HsOverLit lit) = ppr lit ppr_expr (HsPar e) = parens (ppr_lexpr e) +ppr_expr (HsHetMetBrak _ e) = ptext (sLit "<[") <> (ppr_lexpr e) <> ptext (sLit "]>") +ppr_expr (HsHetMetEsc _ _ e) = ptext (sLit "~~") <> (ppr_lexpr e) +ppr_expr (HsHetMetCSP _ e) = ptext (sLit "%%") <> (ppr_lexpr e) ppr_expr (HsCoreAnn s e) = vcat [ptext (sLit "HsCoreAnn") <+> ftext s, ppr_lexpr e] @@ -408,7 +434,7 @@ ppr_expr exprType@(HsCase expr matches) nest 2 (pprMatches (CaseAlt `asTypeOf` idType exprType) matches <+> char '}') ] where idType :: HsExpr id -> HsMatchContext id; idType = undefined -ppr_expr (HsIf e1 e2 e3) +ppr_expr (HsIf _ e1 e2 e3) = sep [hsep [ptext (sLit "if"), nest 2 (ppr e1), ptext (sLit "then")], nest 4 (ppr e2), ptext (sLit "else"), @@ -587,6 +613,7 @@ type HsCmd id = HsExpr id type LHsCmd id = LHsExpr id data HsArrAppType = HsHigherOrderApp | HsFirstOrderApp + deriving (Data, Typeable) \end{code} The legal constructors for commands are: @@ -612,7 +639,8 @@ The legal constructors for commands are: [Match id] -- bodies are HsCmd's SrcLoc - | HsIf (HsExpr id) -- predicate + | HsIf (Maybe (SyntaxExpr id)) -- cond function + (HsExpr id) -- predicate (HsCmd id) -- then part (HsCmd id) -- else part SrcLoc @@ -640,6 +668,7 @@ data HsCmdTop id PostTcType -- return type of the command (SyntaxTable id) -- after type checking: -- names used in the command's desugaring + deriving (Data, Typeable) \end{code} %************************************************************************ @@ -681,6 +710,7 @@ data MatchGroup id PostTcType -- The type is the type of the entire group -- t1 -> ... -> tn -> tr -- where there are n patterns + deriving (Data, Typeable) type LMatch id = Located (Match id) @@ -690,6 +720,7 @@ data Match id (Maybe (LHsType id)) -- A type signature for the result of the match -- Nothing after typechecking (GRHSs id) + deriving (Data, Typeable) isEmptyMatchGroup :: MatchGroup id -> Bool isEmptyMatchGroup (MatchGroup ms _) = null ms @@ -712,13 +743,14 @@ data GRHSs id = GRHSs { grhssGRHSs :: [LGRHS id], -- ^ Guarded RHSs grhssLocalBinds :: (HsLocalBinds id) -- ^ The where clause - } + } deriving (Data, Typeable) type LGRHS id = Located (GRHS id) -- | Guarded Right Hand Side. data GRHS id = GRHS [LStmt id] -- Guards (LHsExpr id) -- Right hand side + deriving (Data, Typeable) \end{code} We know the list must have at least one @Match@ in it. @@ -737,16 +769,16 @@ pprFunBind fun inf matches = pprMatches (FunRhs fun inf) matches pprPatBind :: (OutputableBndr bndr, OutputableBndr id) => LPat bndr -> GRHSs id -> SDoc pprPatBind pat ty@(grhss) - = sep [ppr pat, nest 4 (pprGRHSs (PatBindRhs `asTypeOf` idType ty) grhss)] + = sep [ppr pat, nest 2 (pprGRHSs (PatBindRhs `asTypeOf` idType ty) grhss)] --avoid using PatternSignatures for stage1 code portability where idType :: GRHSs id -> HsMatchContext id; idType = undefined pprMatch :: (OutputableBndr idL, OutputableBndr idR) => HsMatchContext idL -> Match idR -> SDoc pprMatch ctxt (Match pats maybe_ty grhss) - = herald <+> sep [sep (map ppr other_pats), - ppr_maybe_ty, - nest 2 (pprGRHSs ctxt grhss)] + = sep [ sep (herald : map (nest 2 . pprParendLPat) other_pats) + , nest 2 ppr_maybe_ty + , nest 2 (pprGRHSs ctxt grhss) ] where (herald, other_pats) = case ctxt of @@ -756,18 +788,21 @@ pprMatch ctxt (Match pats maybe_ty grhss) -- Not pprBndr; the AbsBinds will -- have printed the signature - | null pats3 -> (pp_infix, []) + | null pats2 -> (pp_infix, []) -- x &&& y = e - | otherwise -> (parens pp_infix, pats3) + | otherwise -> (parens pp_infix, pats2) -- (x &&& y) z = e where - (pat1:pat2:pats3) = pats - pp_infix = ppr pat1 <+> ppr fun <+> ppr pat2 + pp_infix = pprParendLPat pat1 <+> ppr fun <+> pprParendLPat pat2 LambdaExpr -> (char '\\', pats) - _ -> (empty, pats) + + _ -> ASSERT( null pats1 ) + (ppr pat1, []) -- No parens around the single pat + (pat1:pats1) = pats + (pat2:pats2) = pats1 ppr_maybe_ty = case maybe_ty of Just ty -> dcolon <+> ppr ty Nothing -> empty @@ -777,8 +812,8 @@ pprGRHSs :: (OutputableBndr idL, OutputableBndr idR) => HsMatchContext idL -> GRHSs idR -> SDoc pprGRHSs ctxt (GRHSs grhss binds) = vcat (map (pprGRHS ctxt . unLoc) grhss) - $$ if isEmptyLocalBinds binds then empty - else text "where" $$ nest 4 (pprBinds binds) + $$ ppUnless (isEmptyLocalBinds binds) + (text "where" $$ nest 4 (pprBinds binds)) pprGRHS :: (OutputableBndr idL, OutputableBndr idR) => HsMatchContext idL -> GRHS idR -> SDoc @@ -805,15 +840,6 @@ type LStmtLR idL idR = Located (StmtLR idL idR) type Stmt id = StmtLR id id -data GroupByClause id - = GroupByNothing (LHsExpr id) -- Using expression, i.e. - -- "then group using f" ==> GroupByNothing f - | GroupBySomething (Either (LHsExpr id) (SyntaxExpr id)) (LHsExpr id) - -- "then group using f by e" ==> GroupBySomething (Left f) e - -- "then group by e" ==> GroupBySomething (Right _) e: in - -- this case the expression is filled - -- in by the renamer - -- The SyntaxExprs in here are used *only* for do-notation, which -- has rebindable syntax. Otherwise they are unused. data StmtLR idL idR @@ -824,7 +850,7 @@ data StmtLR idL idR -- The fail operator is noSyntaxExpr -- if the pattern match can't fail - | ExprStmt (LHsExpr idR) + | ExprStmt (LHsExpr idR) -- See Note [ExprStmt] (SyntaxExpr idR) -- The (>>) operator PostTcType -- Element type of the RHS (used for arrows) @@ -835,18 +861,32 @@ data StmtLR idL idR -- After renaming, the ids are the binders bound by the stmts and used -- after them - | TransformStmt ([LStmt idL], [idR]) (LHsExpr idR) (Maybe (LHsExpr idR)) - -- After renaming, the IDs are the binders occurring within this - -- transform statement that are used after it - -- "qs, then f by e" ==> TransformStmt (qs, binders) f (Just e) - -- "qs, then f" ==> TransformStmt (qs, binders) f Nothing + -- "qs, then f by e" ==> TransformStmt qs binders f (Just e) + -- "qs, then f" ==> TransformStmt qs binders f Nothing + | TransformStmt + [LStmt idL] -- Stmts are the ones to the left of the 'then' - | GroupStmt ([LStmt idL], [(idR, idR)]) (GroupByClause idR) - -- After renaming, the IDs are the binders occurring within this - -- transform statement that are used after it which are paired with - -- the names which they group over in statements + [idR] -- After renaming, the IDs are the binders occurring + -- within this transform statement that are used after it - -- Recursive statement (see Note [RecStmt] below) + (LHsExpr idR) -- "then f" + + (Maybe (LHsExpr idR)) -- "by e" (optional) + + | GroupStmt + [LStmt idL] -- Stmts to the *left* of the 'group' + -- which generates the tuples to be grouped + + [(idR, idR)] -- See Note [GroupStmt binder map] + + (Maybe (LHsExpr idR)) -- "by e" (optional) + + (Either -- "using f" + (LHsExpr idR) -- Left f => explicit "using f" + (SyntaxExpr idR)) -- Right f => implicit; filled in with 'groupWith' + + + -- Recursive statement (see Note [How RecStmt works] below) | RecStmt { recS_stmts :: [LStmtLR idL idR] @@ -857,12 +897,9 @@ data StmtLR idL idR , recS_rec_ids :: [idR] -- Ditto, but these variables are the "recursive" ones, -- that are used before they are bound in the stmts of -- the RecStmt. - -- An Id can be in both groups -- Both sets of Ids are (now) treated monomorphically - -- The only reason they are separate is becuase the DsArrows - -- code uses them separately, and I don't understand it well - -- enough to change it + -- See Note [How RecStmt works] for why they are separate -- Rebindable syntax , recS_bind_fn :: SyntaxExpr idR -- The bind function @@ -878,12 +915,30 @@ data StmtLR idL idR -- because the Id may be *polymorphic*, but -- the returned thing has to be *monomorphic*, -- so they may be type applications - - , recS_dicts :: DictBinds idR -- Method bindings of Ids bound by the - -- RecStmt, and used afterwards } + deriving (Data, Typeable) \end{code} +Note [GroupStmt binder map] +~~~~~~~~~~~~~~~~~~~~~~~~~~~ +The [(idR,idR)] in a GroupStmt behaves as follows: + + * Before renaming: [] + + * After renaming: + [ (x27,x27), ..., (z35,z35) ] + These are the variables + bound by the stmts to the left of the 'group' + and used either in the 'by' clause, + or in the stmts following the 'group' + Each item is a pair of identical variables. + + * After typechecking: + [ (x27:Int, x27:[Int]), ..., (z35:Bool, z35:[Bool]) ] + Each pair has the same unique, but different *types*. + +Note [ExprStmt] +~~~~~~~~~~~~~~~ ExprStmts are a bit tricky, because what they mean depends on the context. Consider the following contexts: @@ -912,25 +967,30 @@ Array comprehensions are handled like list comprehensions -=chak Note [How RecStmt works] ~~~~~~~~~~~~~~~~~~~~~~~~ Example: - HsDo [ BindStmt x ex + HsDo [ BindStmt x ex - , RecStmt [a::forall a. a -> a, b] - [a::Int -> Int, c] - [ BindStmt b (return x) - , LetStmt a = ea - , BindStmt c ec ] + , RecStmt { recS_rec_ids = [a, c] + , recS_stmts = [ BindStmt b (return (a,c)) + , LetStmt a = ...b... + , BindStmt c ec ] + , recS_later_ids = [a, b] - , return (a b) ] + , return (a b) ] Here, the RecStmt binds a,b,c; but - Only a,b are used in the stmts *following* the RecStmt, - This 'a' is *polymorphic' - Only a,c are used in the stmts *inside* the RecStmt *before* their bindings - This 'a' is monomorphic -Nota Bene: the two a's have different types, even though they -have the same Name. +Why do we need *both* rec_ids and later_ids? For monads they could be +combined into a single set of variables, but not for arrows. That +follows from the types of the respective feedback operators: + + mfix :: MonadFix m => (a -> m a) -> m a + loop :: ArrowLoop a => a (b,d) (c,d) -> a b c + +* For mfix, the 'a' covers the union of the later_ids and the rec_ids +* For 'loop', 'c' is the later_ids and 'd' is the rec_ids Note [Typing a RecStmt] ~~~~~~~~~~~~~~~~~~~~~~~ @@ -954,42 +1014,60 @@ pprStmt (LetStmt binds) = hsep [ptext (sLit "let"), pprBinds binds] pprStmt (ExprStmt expr _ _) = ppr expr pprStmt (ParStmt stmtss) = hsep (map doStmts stmtss) where doStmts stmts = ptext (sLit "| ") <> ppr stmts -pprStmt (TransformStmt (stmts, _) usingExpr maybeByExpr) - = (hsep [stmtsDoc, ptext (sLit "then"), ppr usingExpr, byExprDoc]) - where stmtsDoc = interpp'SP stmts - byExprDoc = maybe empty (\byExpr -> hsep [ptext (sLit "by"), ppr byExpr]) maybeByExpr -pprStmt (GroupStmt (stmts, _) groupByClause) = (hsep [stmtsDoc, ptext (sLit "then group"), pprGroupByClause groupByClause]) - where stmtsDoc = interpp'SP stmts -pprStmt (RecStmt { recS_stmts = segment, recS_rec_ids = rec_ids, recS_later_ids = later_ids }) + +pprStmt (TransformStmt stmts bndrs using by) + = sep (ppr_lc_stmts stmts ++ [pprTransformStmt bndrs using by]) + +pprStmt (GroupStmt stmts _ by using) + = sep (ppr_lc_stmts stmts ++ [pprGroupStmt by using]) + +pprStmt (RecStmt { recS_stmts = segment, recS_rec_ids = rec_ids + , recS_later_ids = later_ids }) = ptext (sLit "rec") <+> vcat [ braces (vcat (map ppr segment)) , ifPprDebug (vcat [ ptext (sLit "rec_ids=") <> ppr rec_ids , ptext (sLit "later_ids=") <> ppr later_ids])] -pprGroupByClause :: (OutputableBndr id) => GroupByClause id -> SDoc -pprGroupByClause (GroupByNothing usingExpr) = hsep [ptext (sLit "using"), ppr usingExpr] -pprGroupByClause (GroupBySomething eitherUsingExpr byExpr) = hsep [ptext (sLit "by"), ppr byExpr, usingExprDoc] - where usingExprDoc = either (\usingExpr -> hsep [ptext (sLit "using"), ppr usingExpr]) (const empty) eitherUsingExpr +pprTransformStmt :: OutputableBndr id => [id] -> LHsExpr id -> Maybe (LHsExpr id) -> SDoc +pprTransformStmt bndrs using by + = sep [ ptext (sLit "then") <+> ifPprDebug (braces (ppr bndrs)) + , nest 2 (ppr using) + , nest 2 (pprBy by)] + +pprGroupStmt :: OutputableBndr id => Maybe (LHsExpr id) + -> Either (LHsExpr id) (SyntaxExpr is) + -> SDoc +pprGroupStmt by using + = sep [ ptext (sLit "then group"), nest 2 (pprBy by), nest 2 (ppr_using using)] + where + ppr_using (Right _) = empty + ppr_using (Left e) = ptext (sLit "using") <+> ppr e + +pprBy :: OutputableBndr id => Maybe (LHsExpr id) -> SDoc +pprBy Nothing = empty +pprBy (Just e) = ptext (sLit "by") <+> ppr e pprDo :: OutputableBndr id => HsStmtContext any -> [LStmt id] -> LHsExpr id -> SDoc pprDo DoExpr stmts body = ptext (sLit "do") <+> ppr_do_stmts stmts body -pprDo (MDoExpr _) stmts body = ptext (sLit "mdo") <+> ppr_do_stmts stmts body -pprDo ListComp stmts body = pprComp brackets stmts body -pprDo PArrComp stmts body = pprComp pa_brackets stmts body +pprDo GhciStmt stmts body = ptext (sLit "do") <+> ppr_do_stmts stmts body +pprDo MDoExpr stmts body = ptext (sLit "mdo") <+> ppr_do_stmts stmts body +pprDo ListComp stmts body = brackets $ pprComp stmts body +pprDo PArrComp stmts body = pa_brackets $ pprComp stmts body pprDo _ _ _ = panic "pprDo" -- PatGuard, ParStmtCxt ppr_do_stmts :: OutputableBndr id => [LStmt id] -> LHsExpr id -> SDoc -- Print a bunch of do stmts, with explicit braces and semicolons, -- so that we are not vulnerable to layout bugs ppr_do_stmts stmts body - = lbrace <+> pprDeeperList vcat ([ ppr s <> semi | s <- stmts] ++ [ppr body]) + = lbrace <+> pprDeeperList vcat ([ppr s <> semi | s <- stmts] ++ [ppr body]) <+> rbrace -pprComp :: OutputableBndr id => (SDoc -> SDoc) -> [LStmt id] -> LHsExpr id -> SDoc -pprComp brack quals body - = brack $ - hang (ppr body <+> char '|') - 4 (interpp'SP quals) +ppr_lc_stmts :: OutputableBndr id => [LStmt id] -> [SDoc] +ppr_lc_stmts stmts = [ppr s <> comma | s <- stmts] + +pprComp :: OutputableBndr id => [LStmt id] -> LHsExpr id -> SDoc +pprComp quals body -- Prints: body | qual1, ..., qualn + = hang (ppr body <+> char '|') 2 (interpp'SP quals) \end{code} %************************************************************************ @@ -1002,31 +1080,43 @@ pprComp brack quals body data HsSplice id = HsSplice -- $z or $(f 4) id -- The id is just a unique name to (LHsExpr id) -- identify this splice point + deriving (Data, Typeable) instance OutputableBndr id => Outputable (HsSplice id) where ppr = pprSplice pprSplice :: OutputableBndr id => HsSplice id -> SDoc pprSplice (HsSplice n e) - = char '$' <> ifPprDebug (brackets (ppr n)) <> pprParendExpr e - - -data HsBracket id = ExpBr (LHsExpr id) -- [| expr |] - | PatBr (LPat id) -- [p| pat |] - | DecBr (HsGroup id) -- [d| decls |] - | TypBr (LHsType id) -- [t| type |] - | VarBr id -- 'x, ''T + = char '$' <> ifPprDebug (brackets (ppr n)) <> eDoc + where + -- We use pprLExpr to match pprParendExpr: + -- Using pprLExpr makes sure that we go 'deeper' + -- I think that is usually (always?) right + pp_as_was = pprLExpr e + eDoc = case unLoc e of + HsPar _ -> pp_as_was + HsVar _ -> pp_as_was + _ -> parens pp_as_was + +data HsBracket id = ExpBr (LHsExpr id) -- [| expr |] + | PatBr (LPat id) -- [p| pat |] + | DecBrL [LHsDecl id] -- [d| decls |]; result of parser + | DecBrG (HsGroup id) -- [d| decls |]; result of renamer + | TypBr (LHsType id) -- [t| type |] + | VarBr id -- 'x, ''T + deriving (Data, Typeable) instance OutputableBndr id => Outputable (HsBracket id) where ppr = pprHsBracket pprHsBracket :: OutputableBndr id => HsBracket id -> SDoc -pprHsBracket (ExpBr e) = thBrackets empty (ppr e) -pprHsBracket (PatBr p) = thBrackets (char 'p') (ppr p) -pprHsBracket (DecBr d) = thBrackets (char 'd') (ppr d) -pprHsBracket (TypBr t) = thBrackets (char 't') (ppr t) -pprHsBracket (VarBr n) = char '\'' <> ppr n +pprHsBracket (ExpBr e) = thBrackets empty (ppr e) +pprHsBracket (PatBr p) = thBrackets (char 'p') (ppr p) +pprHsBracket (DecBrG gp) = thBrackets (char 'd') (ppr gp) +pprHsBracket (DecBrL ds) = thBrackets (char 'd') (vcat (map ppr ds)) +pprHsBracket (TypBr t) = thBrackets (char 't') (ppr t) +pprHsBracket (VarBr n) = char '\'' <> ppr n -- Infelicity: can't show ' vs '', because -- we can't ask n what its OccName is, because the -- pretty-printer for HsExpr doesn't ask for NamedThings @@ -1053,6 +1143,7 @@ data ArithSeqInfo id | FromThenTo (LHsExpr id) (LHsExpr id) (LHsExpr id) + deriving (Data, Typeable) \end{code} \begin{code} @@ -1077,33 +1168,38 @@ pp_dotdot = ptext (sLit " .. ") \begin{code} data HsMatchContext id -- Context of a Match = FunRhs id Bool -- Function binding for f; True <=> written infix - | CaseAlt -- Patterns and guards on a case alternative | LambdaExpr -- Patterns of a lambda + | CaseAlt -- Patterns and guards on a case alternative | ProcExpr -- Patterns of a proc - | PatBindRhs -- Patterns in the *guards* of a pattern binding + | PatBindRhs -- A pattern binding eg [y] <- e = e + | RecUpd -- Record update [used only in DsExpr to -- tell matchWrapper what sort of -- runtime error message to generate] - | StmtCtxt (HsStmtContext id) -- Pattern of a do-stmt or list comprehension - deriving () + + | StmtCtxt (HsStmtContext id) -- Pattern of a do-stmt, list comprehension, + -- pattern guard, etc + + | ThPatQuote -- A Template Haskell pattern quotation [p| (a,b) |] + deriving (Data, Typeable) data HsStmtContext id = ListComp | DoExpr - | MDoExpr PostTcTable -- Recursive do-expression - -- (tiresomely, it needs table - -- of its return/bind ops) + | GhciStmt -- A command-line Stmt in GHCi pat <- rhs + | MDoExpr -- Recursive do-expression | PArrComp -- Parallel array comprehension | PatGuard (HsMatchContext id) -- Pattern guard for specified thing | ParStmtCtxt (HsStmtContext id) -- A branch of a parallel stmt | TransformStmtCtxt (HsStmtContext id) -- A branch of a transform stmt + deriving (Data, Typeable) \end{code} \begin{code} isDoExpr :: HsStmtContext id -> Bool -isDoExpr DoExpr = True -isDoExpr (MDoExpr _) = True -isDoExpr _ = False +isDoExpr DoExpr = True +isDoExpr MDoExpr = True +isDoExpr _ = False isListCompExpr :: HsStmtContext id -> Bool isListCompExpr ListComp = True @@ -1120,19 +1216,30 @@ matchSeparator ProcExpr = ptext (sLit "->") matchSeparator PatBindRhs = ptext (sLit "=") matchSeparator (StmtCtxt _) = ptext (sLit "<-") matchSeparator RecUpd = panic "unused" +matchSeparator ThPatQuote = panic "unused" \end{code} \begin{code} pprMatchContext :: Outputable id => HsMatchContext id -> SDoc -pprMatchContext (FunRhs fun _) = ptext (sLit "the definition of") - <+> quotes (ppr fun) -pprMatchContext CaseAlt = ptext (sLit "a case alternative") -pprMatchContext RecUpd = ptext (sLit "a record-update construct") -pprMatchContext PatBindRhs = ptext (sLit "a pattern binding") -pprMatchContext LambdaExpr = ptext (sLit "a lambda abstraction") -pprMatchContext ProcExpr = ptext (sLit "an arrow abstraction") -pprMatchContext (StmtCtxt ctxt) = ptext (sLit "a pattern binding in") - $$ pprStmtContext ctxt +pprMatchContext ctxt + | want_an ctxt = ptext (sLit "an") <+> pprMatchContextNoun ctxt + | otherwise = ptext (sLit "a") <+> pprMatchContextNoun ctxt + where + want_an (FunRhs {}) = True -- Use "an" in front + want_an ProcExpr = True + want_an _ = False + +pprMatchContextNoun :: Outputable id => HsMatchContext id -> SDoc +pprMatchContextNoun (FunRhs fun _) = ptext (sLit "equation for") + <+> quotes (ppr fun) +pprMatchContextNoun CaseAlt = ptext (sLit "case alternative") +pprMatchContextNoun RecUpd = ptext (sLit "record-update construct") +pprMatchContextNoun ThPatQuote = ptext (sLit "Template Haskell pattern quotation") +pprMatchContextNoun PatBindRhs = ptext (sLit "pattern binding") +pprMatchContextNoun LambdaExpr = ptext (sLit "lambda abstraction") +pprMatchContextNoun ProcExpr = ptext (sLit "arrow abstraction") +pprMatchContextNoun (StmtCtxt ctxt) = ptext (sLit "pattern binding in") + $$ pprStmtContext ctxt pprStmtContext :: Outputable id => HsStmtContext id -> SDoc pprStmtContext (ParStmtCtxt c) @@ -1141,8 +1248,9 @@ pprStmtContext (TransformStmtCtxt c) = sep [ptext (sLit "a transformed branch of"), pprStmtContext c] pprStmtContext (PatGuard ctxt) = ptext (sLit "a pattern guard for") $$ pprMatchContext ctxt +pprStmtContext GhciStmt = ptext (sLit "an interactive GHCi command") pprStmtContext DoExpr = ptext (sLit "a 'do' expression") -pprStmtContext (MDoExpr _) = ptext (sLit "an 'mdo' expression") +pprStmtContext MDoExpr = ptext (sLit "an 'mdo' expression") pprStmtContext ListComp = ptext (sLit "a list comprehension") pprStmtContext PArrComp = ptext (sLit "an array comprehension") @@ -1169,11 +1277,13 @@ matchContextErrString PatBindRhs = ptext (sLit "pattern binding" matchContextErrString RecUpd = ptext (sLit "record update") matchContextErrString LambdaExpr = ptext (sLit "lambda") matchContextErrString ProcExpr = ptext (sLit "proc") +matchContextErrString ThPatQuote = panic "matchContextErrString" -- Not used at runtime matchContextErrString (StmtCtxt (ParStmtCtxt c)) = matchContextErrString (StmtCtxt c) matchContextErrString (StmtCtxt (TransformStmtCtxt c)) = matchContextErrString (StmtCtxt c) matchContextErrString (StmtCtxt (PatGuard _)) = ptext (sLit "pattern guard") +matchContextErrString (StmtCtxt GhciStmt) = ptext (sLit "interactive GHCi command") matchContextErrString (StmtCtxt DoExpr) = ptext (sLit "'do' expression") -matchContextErrString (StmtCtxt (MDoExpr _)) = ptext (sLit "'mdo' expression") +matchContextErrString (StmtCtxt MDoExpr) = ptext (sLit "'mdo' expression") matchContextErrString (StmtCtxt ListComp) = ptext (sLit "list comprehension") matchContextErrString (StmtCtxt PArrComp) = ptext (sLit "array comprehension") \end{code} @@ -1187,5 +1297,10 @@ pprMatchInCtxt ctxt match = hang (ptext (sLit "In") <+> pprMatchContext ctxt <> pprStmtInCtxt :: (OutputableBndr idL, OutputableBndr idR) => HsStmtContext idL -> StmtLR idL idR -> SDoc pprStmtInCtxt ctxt stmt = hang (ptext (sLit "In a stmt of") <+> pprStmtContext ctxt <> colon) - 4 (ppr stmt) + 4 (ppr_stmt stmt) + where + -- For Group and Transform Stmts, don't print the nested stmts! + ppr_stmt (GroupStmt _ _ by using) = pprGroupStmt by using + ppr_stmt (TransformStmt _ bndrs using by) = pprTransformStmt bndrs using by + ppr_stmt stmt = pprStmt stmt \end{code}