X-Git-Url: http://git.megacz.com/?a=blobdiff_plain;f=ghc%2Fcompiler%2FhsSyn%2FHsExpr.lhs;h=5eff4732c2fed47c13f9dd161d2589cbe849c63e;hb=52bd2cc7a9f328e6a7f3f50ac0055a5361f457c1;hp=2004ddf329b8dc10977881d567a0272a69d0bb3d;hpb=6c381e873e222417d9a67aeec77b9555eca7b7a8;p=ghc-hetmet.git diff --git a/ghc/compiler/hsSyn/HsExpr.lhs b/ghc/compiler/hsSyn/HsExpr.lhs index 2004ddf..5eff473 100644 --- a/ghc/compiler/hsSyn/HsExpr.lhs +++ b/ghc/compiler/hsSyn/HsExpr.lhs @@ -1,33 +1,34 @@ % -% (c) The GRASP/AQUA Project, Glasgow University, 1992-1994 +% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998 % \section[HsExpr]{Abstract Haskell syntax: expressions} \begin{code} -#include "HsVersions.h" - module HsExpr where -import Ubiq{-uitous-} -import HsLoop -- for paranoia checking +#include "HsVersions.h" -- friends: -import HsBinds ( HsBinds ) -import HsLit ( HsLit ) -import HsMatches ( pprMatches, pprMatch, Match ) -import HsTypes ( PolyType ) +import HsDecls ( HsGroup ) +import HsBinds ( HsBinds(..), nullBinds ) +import HsPat ( Pat ) +import HsLit ( HsLit, HsOverLit ) +import HsTypes ( HsType, PostTcType, SyntaxName ) +import HsImpExp ( isOperator, pprHsVar ) -- others: -import Id ( DictVar(..), GenId, Id(..) ) -import Outputable -import PprType ( pprType, pprParendType, GenType{-instance-}, GenTyVar{-instance-} ) -import Pretty -import PprStyle ( PprStyle(..) ) +import ForeignCall ( Safety ) +import PprType ( pprParendType ) +import Type ( Type ) +import Var ( TyVar, Id ) +import Name ( Name ) +import NameSet ( FreeVars ) +import DataCon ( DataCon ) +import CStrings ( CLabelString, pprCLabelString ) +import BasicTypes ( IPName, Boxity, tupleParens, Fixity(..) ) import SrcLoc ( SrcLoc ) -import TyVar ( GenTyVar{-instances-} ) -import Usage ( GenUsage{-instance-} ) -import Unique ( Unique{-instances-} ) -import Util ( panic{-ToDo:rm eventually-} ) +import Outputable +import FastString \end{code} %************************************************************************ @@ -37,129 +38,226 @@ import Util ( panic{-ToDo:rm eventually-} ) %************************************************************************ \begin{code} -data HsExpr tyvar uvar id pat - = HsVar id -- variable - | HsLit HsLit -- literal - | HsLitOut HsLit -- TRANSLATION - (GenType tyvar uvar) -- (with its type) +data HsExpr id + = HsVar id -- variable + | HsIPVar (IPName id) -- implicit parameter + | HsOverLit HsOverLit -- Overloaded literals; eliminated by type checker + | HsLit HsLit -- Simple (non-overloaded) literals - | HsLam (Match tyvar uvar id pat) -- lambda - | HsApp (HsExpr tyvar uvar id pat) -- application - (HsExpr tyvar uvar id pat) + | HsLam (Match id) -- lambda + | HsApp (HsExpr id) -- application + (HsExpr id) - -- Operator applications and sections. + -- Operator applications: -- NB Bracketed ops such as (+) come out as Vars. - | OpApp (HsExpr tyvar uvar id pat) -- left operand - (HsExpr tyvar uvar id pat) -- operator - (HsExpr tyvar uvar id pat) -- right operand + -- NB We need an expr for the operator in an OpApp/Section since + -- the typechecker may need to apply the operator to a few types. - -- ADR Question? Why is the "op" in a section an expr when it will - -- have to be of the form (HsVar op) anyway? - -- WDP Answer: But when the typechecker gets ahold of it, it may - -- apply the var to a few types; it will then be an expression. - - | SectionL (HsExpr tyvar uvar id pat) -- operand - (HsExpr tyvar uvar id pat) -- operator - | SectionR (HsExpr tyvar uvar id pat) -- operator - (HsExpr tyvar uvar id pat) -- operand - + | OpApp (HsExpr id) -- left operand + (HsExpr id) -- operator + Fixity -- Renamer adds fixity; bottom until then + (HsExpr id) -- right operand - | HsCase (HsExpr tyvar uvar id pat) - [Match tyvar uvar id pat] -- must have at least one Match - SrcLoc + -- We preserve prefix negation and parenthesis for the precedence parser. + -- They are eventually removed by the type checker. - | HsIf (HsExpr tyvar uvar id pat) -- predicate - (HsExpr tyvar uvar id pat) -- then part - (HsExpr tyvar uvar id pat) -- else part - SrcLoc + | NegApp (HsExpr id) -- negated expr + SyntaxName -- Name of 'negate' (see RnEnv.lookupSyntaxName) - | HsLet (HsBinds tyvar uvar id pat) -- let(rec) - (HsExpr tyvar uvar id pat) + | HsPar (HsExpr id) -- parenthesised expr - | HsDo [Stmt tyvar uvar id pat] -- "do":one or more stmts + | SectionL (HsExpr id) -- operand + (HsExpr id) -- operator + | SectionR (HsExpr id) -- operator + (HsExpr id) -- operand + + | HsCase (HsExpr id) + [Match id] SrcLoc - | HsDoOut [Stmt tyvar uvar id pat] -- "do":one or more stmts - id id -- Monad and MonadZero dicts + | HsIf (HsExpr id) -- predicate + (HsExpr id) -- then part + (HsExpr id) -- else part SrcLoc - | ListComp (HsExpr tyvar uvar id pat) -- list comprehension - [Qual tyvar uvar id pat] -- at least one Qual(ifier) + | HsLet (HsBinds id) -- let(rec) + (HsExpr id) + + | HsDo (HsStmtContext Name) -- The parameterisation is unimportant + -- because in this context we never use + -- the PatGuard or ParStmt variant + [Stmt id] -- "do":one or more stmts + (ReboundNames id) -- Ids for [return,fail,>>=,>>] + PostTcType -- Type of the whole expression + SrcLoc | ExplicitList -- syntactic list - [HsExpr tyvar uvar id pat] - | ExplicitListOut -- TRANSLATION - (GenType tyvar uvar) -- Gives type of components of list - [HsExpr tyvar uvar id pat] + PostTcType -- Gives type of components of list + [HsExpr id] + + | ExplicitPArr -- syntactic parallel array: [:e1, ..., en:] + PostTcType -- type of elements of the parallel array + [HsExpr id] | ExplicitTuple -- tuple - [HsExpr tyvar uvar id pat] + [HsExpr id] -- NB: Unit is ExplicitTuple [] -- for tuples, we can get the types -- direct from the components + Boxity - | RecordCon id -- record construction - [(id, Maybe (HsExpr tyvar uvar id pat))] - | RecordUpd (HsExpr tyvar uvar id pat) -- record update - [(id, Maybe (HsExpr tyvar uvar id pat))] + -- Record construction + | RecordCon id -- The constructor + (HsRecordBinds id) - | ExprWithTySig -- signature binding - (HsExpr tyvar uvar id pat) - (PolyType id) - | ArithSeqIn -- arithmetic sequence - (ArithSeqInfo tyvar uvar id pat) - | ArithSeqOut - (HsExpr tyvar uvar id pat) -- (typechecked, of course) - (ArithSeqInfo tyvar uvar id pat) + | RecordConOut DataCon + (HsExpr id) -- Data con Id applied to type args + (HsRecordBinds id) + + + -- Record update + | RecordUpd (HsExpr id) + (HsRecordBinds id) + + | RecordUpdOut (HsExpr id) -- TRANSLATION + Type -- Type of *input* record + Type -- Type of *result* record (may differ from + -- type of input record) + (HsRecordBinds id) - | CCall FAST_STRING -- call into the C world; string is - [HsExpr tyvar uvar id pat] -- the C function; exprs are the + | ExprWithTySig -- signature binding + (HsExpr id) + (HsType id) + | ArithSeqIn -- arithmetic sequence + (ArithSeqInfo id) + | ArithSeqOut + (HsExpr id) -- (typechecked, of course) + (ArithSeqInfo id) + | PArrSeqIn -- arith. sequence for parallel array + (ArithSeqInfo id) -- [:e1..e2:] or [:e1, e2..e3:] + | PArrSeqOut + (HsExpr id) -- (typechecked, of course) + (ArithSeqInfo id) + + | HsCCall CLabelString -- call into the C world; string is + [HsExpr id] -- the C function; exprs are the -- arguments to pass. - Bool -- True <=> might cause Haskell + Safety -- True <=> might cause Haskell -- garbage-collection (must generate -- more paranoid code) Bool -- True <=> it's really a "casm" -- NOTE: this CCall is the *boxed* -- version; the desugarer will convert -- it into the unboxed "ccall#". - (GenType tyvar uvar) -- The result type; will be *bottom* + PostTcType -- The result type; will be *bottom* -- until the typechecker gets ahold of it - | HsSCC FAST_STRING -- "set cost centre" (_scc_) annotation - (HsExpr tyvar uvar id pat) -- expr whose cost is to be measured + | HsSCC FastString -- "set cost centre" (_scc_) annotation + (HsExpr id) -- expr whose cost is to be measured + + | HsCoreAnn FastString -- hdaume: core annotation + (HsExpr id) + + ----------------------------------------------------------- + -- MetaHaskell Extensions + | HsBracket (HsBracket id) SrcLoc + + | HsBracketOut (HsBracket Name) -- Output of the type checker is the *original* + [PendingSplice] -- renamed expression, plus *typechecked* splices + -- to be pasted back in by the desugarer + + | HsSplice id (HsExpr id) SrcLoc -- $z or $(f 4) + -- The id is just a unique name to + -- identify this splice point + + | HsReify (HsReify id) -- reifyType t, reifyDecl i, reifyFixity + + ----------------------------------------------------------- + -- Arrow notation extension + + | HsProc (Pat id) -- arrow abstraction, proc + (HsCmdTop id) -- body of the abstraction + -- always has an empty stack + SrcLoc + + --------------------------------------- + -- The following are commands, not expressions proper + + | HsArrApp -- Arrow tail, or arrow application (f -< arg) + (HsExpr id) -- arrow expression, f + (HsExpr id) -- input expression, arg + PostTcType -- type of the arrow expressions f, + -- of the form a t t', where arg :: t + HsArrAppType -- higher-order (-<<) or first-order (-<) + Bool -- True => right-to-left (f -< arg) + -- False => left-to-right (arg >- f) + SrcLoc + + | HsArrForm -- Command formation, (| e cmd1 .. cmdn |) + (HsExpr id) -- the operator + -- after type-checking, a type abstraction to be + -- applied to the type of the local environment tuple + (Maybe Fixity) -- fixity (filled in by the renamer), for forms that + -- were converted from OpApp's by the renamer + [HsCmdTop id] -- argument commands + SrcLoc + +\end{code} + + +These constructors only appear temporarily in the parser. +The renamer translates them into the Right Thing. + +\begin{code} + | EWildPat -- wildcard + + | EAsPat id -- as pattern + (HsExpr id) + + | ELazyPat (HsExpr id) -- ~ pattern + + | HsType (HsType id) -- Explicit type argument; e.g f {| Int |} x y \end{code} Everything from here on appears only in typechecker output. \begin{code} | TyLam -- TRANSLATION - [tyvar] - (HsExpr tyvar uvar id pat) + [TyVar] + (HsExpr id) | TyApp -- TRANSLATION - (HsExpr tyvar uvar id pat) -- generated by Spec - [GenType tyvar uvar] + (HsExpr id) -- generated by Spec + [Type] -- DictLam and DictApp are "inverses" | DictLam [id] - (HsExpr tyvar uvar id pat) + (HsExpr id) | DictApp - (HsExpr tyvar uvar id pat) + (HsExpr id) [id] - -- ClassDictLam and Dictionary are "inverses" (see note below) - | ClassDictLam - [id] -- superclass dicts - [id] -- methods - (HsExpr tyvar uvar id pat) - | Dictionary - [id] -- superclass dicts - [id] -- methods - - | SingleDict -- a simple special case of Dictionary - id -- local dictionary name +type PendingSplice = (Name, HsExpr Id) -- Typechecked splices, waiting to be + -- pasted back in by the desugarer +\end{code} + +Table of bindings of names used in rebindable syntax. +This gets filled in by the renamer. + +\begin{code} +type ReboundNames id = [(Name, HsExpr id)] +-- * Before the renamer, this list is empty +-- +-- * 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, )] +-- where is the evidence for the method \end{code} A @Dictionary@, unless of length 0 or 1, becomes a tuple. A @@ -169,188 +267,293 @@ A @Dictionary@, unless of length 0 or 1, becomes a tuple. A \end{verbatim} \begin{code} -instance (NamedThing id, Outputable id, Outputable pat, - Eq tyvar, Outputable tyvar, Eq uvar, Outputable uvar) => - Outputable (HsExpr tyvar uvar id pat) where - ppr = pprExpr +instance OutputableBndr id => Outputable (HsExpr id) where + ppr expr = pprExpr expr \end{code} \begin{code} -pprExpr sty (HsVar v) - = (if (isOpLexeme v) then ppParens else id) (ppr sty v) +pprExpr :: OutputableBndr id => HsExpr id -> SDoc -pprExpr sty (HsLit lit) = ppr sty lit -pprExpr sty (HsLitOut lit _) = ppr sty lit +pprExpr e = pprDeeper (ppr_expr e) +pprBinds b = pprDeeper (ppr b) -pprExpr sty (HsLam match) - = ppCat [ppStr "\\", ppNest 2 (pprMatch sty True match)] +ppr_expr (HsVar v) = pprHsVar v +ppr_expr (HsIPVar v) = ppr v +ppr_expr (HsLit lit) = ppr lit +ppr_expr (HsOverLit lit) = ppr lit -pprExpr sty expr@(HsApp e1 e2) +ppr_expr (HsLam match) = pprMatch LambdaExpr match + +ppr_expr expr@(HsApp e1 e2) = let (fun, args) = collect_args expr [] in - ppHang (pprParendExpr sty fun) 4 (ppSep (map (pprParendExpr sty) args)) + (ppr_expr fun) <+> (sep (map pprParendExpr args)) where collect_args (HsApp fun arg) args = collect_args fun (arg:args) collect_args fun args = (fun, args) -pprExpr sty (OpApp e1 op e2) +ppr_expr (OpApp e1 op fixity e2) = case op of HsVar v -> pp_infixly v _ -> pp_prefixly where - pp_e1 = pprParendExpr sty e1 - pp_e2 = pprParendExpr sty e2 + pp_e1 = pprParendExpr e1 -- Add parens to make precedence clear + pp_e2 = pprParendExpr e2 pp_prefixly - = ppHang (pprParendExpr sty op) 4 (ppSep [pp_e1, pp_e2]) + = hang (pprExpr op) 4 (sep [pp_e1, pp_e2]) pp_infixly v - = ppSep [pp_e1, ppCat [pprOp sty v, pp_e2]] + = sep [pp_e1, hsep [pprInfix v, pp_e2]] + +ppr_expr (NegApp e _) = char '-' <+> pprParendExpr e + +ppr_expr (HsPar e) = parens (ppr_expr e) -pprExpr sty (SectionL expr op) +ppr_expr (SectionL expr op) = case op of HsVar v -> pp_infixly v _ -> pp_prefixly where - pp_expr = pprParendExpr sty expr + pp_expr = pprParendExpr expr - pp_prefixly = ppHang (ppCat [ppStr "( \\ _x ->", ppr sty op]) - 4 (ppCat [pp_expr, ppStr "_x )"]) - pp_infixly v - = ppSep [ ppBeside ppLparen pp_expr, - ppBeside (pprOp sty v) ppRparen ] + pp_prefixly = hang (hsep [text " \\ x_ ->", ppr op]) + 4 (hsep [pp_expr, ptext SLIT("x_ )")]) + pp_infixly v = parens (sep [pp_expr, ppr v]) -pprExpr sty (SectionR op expr) +ppr_expr (SectionR op expr) = case op of HsVar v -> pp_infixly v _ -> pp_prefixly where - pp_expr = pprParendExpr sty expr + pp_expr = pprParendExpr expr - pp_prefixly = ppHang (ppCat [ppStr "( \\ _x ->", ppr sty op, ppPStr SLIT("_x")]) - 4 (ppBeside pp_expr ppRparen) + pp_prefixly = hang (hsep [text "( \\ x_ ->", ppr op, ptext SLIT("x_")]) + 4 ((<>) pp_expr rparen) pp_infixly v - = ppSep [ ppBeside ppLparen (pprOp sty v), - ppBeside pp_expr ppRparen ] - -pprExpr sty (CCall fun args _ is_asm result_ty) - = ppHang (if is_asm - then ppBesides [ppStr "_casm_ ``", ppPStr fun, ppStr "''"] - else ppBeside (ppPStr SLIT("_ccall_ ")) (ppPStr fun)) - 4 (ppSep (map (pprParendExpr sty) args)) + = parens (sep [ppr v, pp_expr]) -pprExpr sty (HsSCC label expr) - = ppSep [ ppBeside (ppPStr SLIT("_scc_ ")) (ppBesides [ppChar '"', ppPStr label, ppChar '"']), - pprParendExpr sty expr ] +ppr_expr (HsCase expr matches _) + = sep [ sep [ptext SLIT("case"), nest 4 (pprExpr expr), ptext SLIT("of")], + nest 2 (pprMatches CaseAlt matches) ] -pprExpr sty (HsCase expr matches _) - = ppSep [ ppSep [ppPStr SLIT("case"), ppNest 4 (pprExpr sty expr), ppPStr SLIT("of")], - ppNest 2 (pprMatches sty (True, ppNil) matches) ] - -pprExpr sty (ListComp expr quals) - = ppHang (ppCat [ppLbrack, pprExpr sty expr, ppChar '|']) - 4 (ppSep [interpp'SP sty quals, ppRbrack]) +ppr_expr (HsIf e1 e2 e3 _) + = sep [hsep [ptext SLIT("if"), nest 2 (pprExpr e1), ptext SLIT("then")], + nest 4 (pprExpr e2), + ptext SLIT("else"), + nest 4 (pprExpr e3)] -- special case: let ... in let ... -pprExpr sty (HsLet binds expr@(HsLet _ _)) - = ppSep [ppHang (ppPStr SLIT("let")) 2 (ppCat [ppr sty binds, ppPStr SLIT("in")]), - ppr sty expr] - -pprExpr sty (HsLet binds expr) - = ppSep [ppHang (ppPStr SLIT("let")) 2 (ppr sty binds), - ppHang (ppPStr SLIT("in")) 2 (ppr sty expr)] - -pprExpr sty (HsDo stmts _) - = ppCat [ppPStr SLIT("do"), ppAboves (map (ppr sty) stmts)] - -pprExpr sty (HsIf e1 e2 e3 _) - = ppSep [ppCat [ppPStr SLIT("if"), ppNest 2 (pprExpr sty e1), ppPStr SLIT("then")], - ppNest 4 (pprExpr sty e2), - ppPStr SLIT("else"), - ppNest 4 (pprExpr sty e3)] - -pprExpr sty (ExplicitList exprs) - = ppBracket (ppInterleave ppComma (map (pprExpr sty) exprs)) -pprExpr sty (ExplicitListOut ty exprs) - = ppBesides [ ppBracket (ppInterleave ppComma (map (pprExpr sty) exprs)), - ifnotPprForUser sty (ppBeside ppSP (ppParens (pprType sty ty))) ] - -pprExpr sty (ExplicitTuple exprs) - = ppParens (ppInterleave ppComma (map (pprExpr sty) exprs)) -pprExpr sty (ExprWithTySig expr sig) - = ppHang (ppBesides [ppLparen, ppNest 2 (pprExpr sty expr), ppPStr SLIT(" ::")]) - 4 (ppBeside (ppr sty sig) ppRparen) - -pprExpr sty (RecordCon con rbinds) - = pp_rbinds sty (ppr sty con) rbinds - -pprExpr sty (RecordUpd aexp rbinds) - = pp_rbinds sty (pprParendExpr sty aexp) rbinds - -pprExpr sty (ArithSeqIn info) - = ppBracket (ppr sty info) -pprExpr sty (ArithSeqOut expr info) - = case sty of - PprForUser -> - ppBracket (ppr sty info) - _ -> - ppBesides [ppLbrack, ppParens (ppr sty expr), ppr sty info, ppRbrack] - -pprExpr sty (TyLam tyvars expr) - = ppHang (ppCat [ppStr "/\\", interppSP sty tyvars, ppStr "->"]) - 4 (pprExpr sty expr) - -pprExpr sty (TyApp expr [ty]) - = ppHang (pprExpr sty expr) 4 (pprParendType sty ty) - -pprExpr sty (TyApp expr tys) - = ppHang (pprExpr sty expr) - 4 (ppBracket (interpp'SP sty tys)) - -pprExpr sty (DictLam dictvars expr) - = ppHang (ppCat [ppStr "\\{-dict-}", interppSP sty dictvars, ppStr "->"]) - 4 (pprExpr sty expr) - -pprExpr sty (DictApp expr [dname]) - = ppHang (pprExpr sty expr) 4 (ppr sty dname) - -pprExpr sty (DictApp expr dnames) - = ppHang (pprExpr sty expr) - 4 (ppBracket (interpp'SP sty dnames)) - -pprExpr sty (ClassDictLam dicts methods expr) - = ppHang (ppCat [ppStr "\\{-classdict-}", - ppBracket (interppSP sty dicts), - ppBracket (interppSP sty methods), - ppStr "->"]) - 4 (pprExpr sty expr) - -pprExpr sty (Dictionary dicts methods) - = ppSep [ppBesides [ppLparen, ppPStr SLIT("{-dict-}")], - ppBracket (interpp'SP sty dicts), - ppBesides [ppBracket (interpp'SP sty methods), ppRparen]] - -pprExpr sty (SingleDict dname) - = ppCat [ppPStr SLIT("{-singleDict-}"), ppr sty dname] +ppr_expr (HsLet binds expr@(HsLet _ _)) + = sep [hang (ptext SLIT("let")) 2 (hsep [pprBinds binds, ptext SLIT("in")]), + pprExpr expr] + +ppr_expr (HsLet binds expr) + = sep [hang (ptext SLIT("let")) 2 (pprBinds binds), + hang (ptext SLIT("in")) 2 (ppr expr)] + +ppr_expr (HsDo do_or_list_comp stmts _ _ _) = pprDo do_or_list_comp stmts + +ppr_expr (ExplicitList _ exprs) + = brackets (fsep (punctuate comma (map ppr_expr exprs))) + +ppr_expr (ExplicitPArr _ exprs) + = pa_brackets (fsep (punctuate comma (map ppr_expr exprs))) + +ppr_expr (ExplicitTuple exprs boxity) + = tupleParens boxity (sep (punctuate comma (map ppr_expr exprs))) + +ppr_expr (RecordCon con_id rbinds) + = pp_rbinds (ppr con_id) rbinds +ppr_expr (RecordConOut data_con con rbinds) + = pp_rbinds (ppr con) rbinds + +ppr_expr (RecordUpd aexp rbinds) + = pp_rbinds (pprParendExpr aexp) rbinds +ppr_expr (RecordUpdOut aexp _ _ rbinds) + = pp_rbinds (pprParendExpr aexp) rbinds + +ppr_expr (ExprWithTySig expr sig) + = hang (nest 2 (ppr_expr expr) <+> dcolon) + 4 (ppr sig) + +ppr_expr (ArithSeqIn info) + = brackets (ppr info) +ppr_expr (ArithSeqOut expr info) + = brackets (ppr info) + +ppr_expr (PArrSeqIn info) + = pa_brackets (ppr info) +ppr_expr (PArrSeqOut expr info) + = pa_brackets (ppr info) + +ppr_expr EWildPat = char '_' +ppr_expr (ELazyPat e) = char '~' <> pprParendExpr e +ppr_expr (EAsPat v e) = ppr v <> char '@' <> pprParendExpr e + +ppr_expr (HsCCall fun args _ is_asm result_ty) + = hang (if is_asm + then ptext SLIT("_casm_ ``") <> pprCLabelString fun <> ptext SLIT("''") + else ptext SLIT("_ccall_") <+> pprCLabelString fun) + 4 (sep (map pprParendExpr args)) + +ppr_expr (HsSCC lbl expr) + = sep [ ptext SLIT("_scc_") <+> doubleQuotes (ftext lbl), pprParendExpr expr ] + +ppr_expr (TyLam tyvars expr) + = hang (hsep [ptext SLIT("/\\"), + hsep (map (pprBndr LambdaBind) tyvars), + ptext SLIT("->")]) + 4 (ppr_expr expr) + +ppr_expr (TyApp expr [ty]) + = hang (ppr_expr expr) 4 (pprParendType ty) + +ppr_expr (TyApp expr tys) + = hang (ppr_expr expr) + 4 (brackets (interpp'SP tys)) + +ppr_expr (DictLam dictvars expr) + = hang (hsep [ptext SLIT("\\{-dict-}"), + hsep (map (pprBndr LambdaBind) dictvars), + ptext SLIT("->")]) + 4 (ppr_expr expr) + +ppr_expr (DictApp expr [dname]) + = hang (ppr_expr expr) 4 (ppr dname) + +ppr_expr (DictApp expr dnames) + = hang (ppr_expr expr) + 4 (brackets (interpp'SP dnames)) + +ppr_expr (HsType id) = ppr id + +ppr_expr (HsSplice n e _) = char '$' <> brackets (ppr n) <> pprParendExpr e +ppr_expr (HsBracket b _) = pprHsBracket b +ppr_expr (HsBracketOut e ps) = ppr e $$ ptext SLIT("where") <+> ppr ps +ppr_expr (HsReify r) = ppr r + +ppr_expr (HsProc pat (HsCmdTop cmd _ _ _) _) + = hsep [ptext SLIT("proc"), ppr pat, ptext SLIT("->"), pprExpr cmd] + +ppr_expr (HsArrApp arrow arg _ HsFirstOrderApp True _) + = hsep [pprExpr arrow, ptext SLIT("-<"), pprExpr arg] +ppr_expr (HsArrApp arrow arg _ HsFirstOrderApp False _) + = hsep [pprExpr arg, ptext SLIT(">-"), pprExpr arrow] +ppr_expr (HsArrApp arrow arg _ HsHigherOrderApp True _) + = hsep [pprExpr arrow, ptext SLIT("-<<"), pprExpr arg] +ppr_expr (HsArrApp arrow arg _ HsHigherOrderApp False _) + = hsep [pprExpr arg, ptext SLIT(">>-"), pprExpr arrow] + +ppr_expr (HsArrForm (HsVar v) (Just _) [arg1, arg2] _) + = sep [pprCmdArg arg1, hsep [pprInfix v, pprCmdArg arg2]] +ppr_expr (HsArrForm op _ args _) + = hang (ptext SLIT("(|") <> pprExpr op) + 4 (sep (map pprCmdArg args) <> ptext SLIT("|)")) + +pprCmdArg :: OutputableBndr id => HsCmdTop id -> SDoc +pprCmdArg (HsCmdTop cmd@(HsArrForm _ Nothing [] _) _ _ _) = pprExpr cmd +pprCmdArg (HsCmdTop cmd _ _ _) = parens (pprExpr cmd) + +-- Put a var in backquotes if it's not an operator already +pprInfix :: Outputable name => name -> SDoc +pprInfix v | isOperator ppr_v = ppr_v + | otherwise = char '`' <> ppr_v <> char '`' + where + ppr_v = ppr v + +-- add parallel array brackets around a document +-- +pa_brackets :: SDoc -> SDoc +pa_brackets p = ptext SLIT("[:") <> p <> ptext SLIT(":]") \end{code} Parenthesize unless very simple: \begin{code} -pprParendExpr :: (NamedThing id, Outputable id, Outputable pat, - Eq tyvar, Outputable tyvar, Eq uvar, Outputable uvar) - => PprStyle -> HsExpr tyvar uvar id pat -> Pretty +pprParendExpr :: OutputableBndr id => HsExpr id -> SDoc -pprParendExpr sty expr +pprParendExpr expr = let - pp_as_was = pprExpr sty expr + pp_as_was = pprExpr expr in case expr of - HsLit l -> ppr sty l - HsLitOut l _ -> ppr sty l + HsLit l -> ppr l + HsOverLit l -> ppr l + HsVar _ -> pp_as_was - ExplicitList _ -> pp_as_was - ExplicitListOut _ _ -> pp_as_was - ExplicitTuple _ -> pp_as_was - _ -> ppParens pp_as_was + HsIPVar _ -> pp_as_was + ExplicitList _ _ -> pp_as_was + ExplicitPArr _ _ -> pp_as_was + ExplicitTuple _ _ -> pp_as_was + HsPar _ -> pp_as_was + + _ -> parens pp_as_was +\end{code} + +%************************************************************************ +%* * +\subsection{Commands (in arrow abstractions)} +%* * +%************************************************************************ + +We re-use HsExpr to represent these. + +\begin{code} +type HsCmd id = HsExpr id + +data HsArrAppType = HsHigherOrderApp | HsFirstOrderApp +\end{code} + +The legal constructors for commands are: + + = HsArrApp ... -- as above + + | HsArrForm ... -- as above + + | HsApp (HsCmd id) + (HsExpr id) + + | HsLam (Match id) -- kappa + + -- the renamer turns this one into HsArrForm + | OpApp (HsExpr id) -- left operand + (HsCmd id) -- operator + Fixity -- Renamer adds fixity; bottom until then + (HsCmd id) -- right operand + + | HsPar (HsCmd id) -- parenthesised command + + | HsCase (HsExpr id) + [Match id] -- bodies are HsCmd's + SrcLoc + + | HsIf (HsExpr id) -- predicate + (HsCmd id) -- then part + (HsCmd id) -- else part + SrcLoc + + | HsLet (HsBinds id) -- let(rec) + (HsCmd id) + + | HsDo (HsStmtContext Name) -- The parameterisation is unimportant + -- because in this context we never use + -- the PatGuard or ParStmt variant + [Stmt id] -- HsExpr's are really HsCmd's + (ReboundNames id) + PostTcType -- Type of the whole expression + SrcLoc + +Top-level command, introducing a new arrow. +This may occur inside a proc (where the stack is empty) or as an +argument of a command-forming operator. + +\begin{code} +data HsCmdTop id + = HsCmdTop (HsCmd id) + [PostTcType] -- types of inputs on the command's stack + PostTcType -- return type of the command + (ReboundNames id) + -- after type checking: + -- names used in the command's desugaring \end{code} %************************************************************************ @@ -360,44 +563,284 @@ pprParendExpr sty expr %************************************************************************ \begin{code} -pp_rbinds sty thing rbinds - = ppHang thing 4 - (ppBesides [ppChar '{', ppInterleave ppComma (map (pp_rbind sty) rbinds), ppChar '}']) +type HsRecordBinds id = [(id, HsExpr id)] + +recBindFields :: HsRecordBinds id -> [id] +recBindFields rbinds = [field | (field,_) <- rbinds] -pp_rbind :: (NamedThing id, Outputable id, Outputable pat, - Eq tyvar, Outputable tyvar, Eq uvar, Outputable uvar) - => PprStyle -> (id, Maybe (HsExpr tyvar uvar id pat)) -> Pretty +pp_rbinds :: OutputableBndr id => SDoc -> HsRecordBinds id -> SDoc -pp_rbind sty (v, Nothing) = ppr sty v -pp_rbind sty (v, Just e) = ppCat [ppr sty v, ppStr "<-", ppr sty e] +pp_rbinds thing rbinds + = hang thing + 4 (braces (sep (punctuate comma (map (pp_rbind) rbinds)))) + where + pp_rbind (v, e) = hsep [pprBndr LetBind v, char '=', ppr e] \end{code} + + %************************************************************************ %* * -\subsection{Do stmts} +\subsection{@Match@, @GRHSs@, and @GRHS@ datatypes} %* * %************************************************************************ +@Match@es are sets of pattern bindings and right hand sides for +functions, patterns or case branches. For example, if a function @g@ +is defined as: +\begin{verbatim} +g (x,y) = y +g ((x:ys),y) = y+1, +\end{verbatim} +then \tr{g} has two @Match@es: @(x,y) = y@ and @((x:ys),y) = y+1@. + +It is always the case that each element of an @[Match]@ list has the +same number of @pats@s inside it. This corresponds to saying that +a function defined by pattern matching must have the same number of +patterns in each equation. + \begin{code} -data Stmt tyvar uvar id pat - = BindStmt pat - (HsExpr tyvar uvar id pat) - SrcLoc - | ExprStmt (HsExpr tyvar uvar id pat) - SrcLoc - | LetStmt (HsBinds tyvar uvar id pat) +data Match id + = Match + [Pat id] -- The patterns + (Maybe (HsType id)) -- A type signature for the result of the match + -- Nothing after typechecking + + (GRHSs id) + +-- GRHSs are used both for pattern bindings and for Matches +data GRHSs id + = GRHSs [GRHS id] -- Guarded RHSs + (HsBinds id) -- The where clause + PostTcType -- Type of RHS (after type checking) + +data GRHS id + = GRHS [Stmt id] -- The RHS is the final ResultStmt + SrcLoc + +mkSimpleMatch :: [Pat id] -> HsExpr id -> Type -> SrcLoc -> Match id +mkSimpleMatch pats rhs rhs_ty locn + = Match pats Nothing (GRHSs (unguardedRHS rhs locn) EmptyBinds rhs_ty) + +unguardedRHS :: HsExpr id -> SrcLoc -> [GRHS id] +unguardedRHS rhs loc = [GRHS [ResultStmt rhs loc] loc] + +glueBindsOnGRHSs :: HsBinds id -> GRHSs id -> GRHSs id +glueBindsOnGRHSs EmptyBinds grhss = grhss +glueBindsOnGRHSs binds1 (GRHSs grhss binds2 ty) + = GRHSs grhss (binds1 `ThenBinds` binds2) ty \end{code} +@getMatchLoc@ takes a @Match@ and returns the +source-location gotten from the GRHS inside. +THis is something of a nuisance, but no more. + \begin{code} -instance (NamedThing id, Outputable id, Outputable pat, - Eq tyvar, Outputable tyvar, Eq uvar, Outputable uvar) => - Outputable (Stmt tyvar uvar id pat) where - ppr sty (BindStmt pat expr _) - = ppCat [ppr sty pat, ppStr "<-", ppr sty expr] - ppr sty (LetStmt binds) - = ppCat [ppPStr SLIT("let"), ppr sty binds] - ppr sty (ExprStmt expr _) - = ppr sty expr +getMatchLoc :: Match id -> SrcLoc +getMatchLoc (Match _ _ (GRHSs (GRHS _ loc : _) _ _)) = loc +\end{code} + +We know the list must have at least one @Match@ in it. + +\begin{code} +pprMatches :: (OutputableBndr id) => HsMatchContext id -> [Match id] -> SDoc +pprMatches ctxt matches = vcat (map (pprMatch ctxt) matches) + +-- Exported to HsBinds, which can't see the defn of HsMatchContext +pprFunBind :: (OutputableBndr id) => id -> [Match id] -> SDoc +pprFunBind fun matches = pprMatches (FunRhs fun) matches + +-- Exported to HsBinds, which can't see the defn of HsMatchContext +pprPatBind :: (OutputableBndr id) + => Pat id -> GRHSs id -> SDoc +pprPatBind pat grhss = sep [ppr pat, nest 4 (pprGRHSs PatBindRhs grhss)] + + +pprMatch :: OutputableBndr id => HsMatchContext id -> Match id -> SDoc +pprMatch ctxt (Match pats maybe_ty grhss) + = pp_name ctxt <+> sep [sep (map ppr pats), + ppr_maybe_ty, + nest 2 (pprGRHSs ctxt grhss)] + where + pp_name (FunRhs fun) = ppr fun -- Not pprBndr; the AbsBinds will + -- have printed the signature + pp_name LambdaExpr = char '\\' + pp_name other = empty + + ppr_maybe_ty = case maybe_ty of + Just ty -> dcolon <+> ppr ty + Nothing -> empty + + +pprGRHSs :: OutputableBndr id => HsMatchContext id -> GRHSs id -> SDoc +pprGRHSs ctxt (GRHSs grhss binds ty) + = vcat (map (pprGRHS ctxt) grhss) + $$ + (if nullBinds binds then empty + else text "where" $$ nest 4 (pprDeeper (ppr binds))) + + +pprGRHS :: OutputableBndr id => HsMatchContext id -> GRHS id -> SDoc + +pprGRHS ctxt (GRHS [ResultStmt expr _] locn) + = pp_rhs ctxt expr + +pprGRHS ctxt (GRHS guarded locn) + = sep [char '|' <+> interpp'SP guards, pp_rhs ctxt expr] + where + ResultStmt expr _ = last guarded -- Last stmt should be a ResultStmt for guards + guards = init guarded + +pp_rhs ctxt rhs = matchSeparator ctxt <+> pprDeeper (ppr rhs) +\end{code} + + + +%************************************************************************ +%* * +\subsection{Do stmts and list comprehensions} +%* * +%************************************************************************ + +\begin{code} +data Stmt id + = BindStmt (Pat id) (HsExpr id) SrcLoc + | LetStmt (HsBinds id) + | ResultStmt (HsExpr id) SrcLoc -- See notes that follow + | ExprStmt (HsExpr id) PostTcType SrcLoc -- See notes that follow + -- The type is the *element type* of the expression + + -- ParStmts only occur in a list comprehension + | ParStmt [([Stmt id], [id])] -- After remaing, the ids are the binders + -- bound by the stmts and used subsequently + + -- Recursive statement + | RecStmt [Stmt id] + --- The next two fields are only valid after renaming + [id] -- The ids are a subset of the variables bound by the stmts + -- that are used in stmts that follow the RecStmt + + [id] -- Ditto, but these variables are the "recursive" ones, that + -- are used before they are bound in the stmts of the RecStmt + -- From a type-checking point of view, these ones have to be monomorphic + + --- This field is only valid after typechecking + [HsExpr id] -- These expressions correspond + -- 1-to-1 with the "recursive" [id], and are the expresions that + -- should be returned by the recursion. They may not quite be the + -- Ids themselves, because the Id may be *polymorphic*, but + -- the returned thing has to be *monomorphic*. +\end{code} + +ExprStmts and ResultStmts are a bit tricky, because what they mean +depends on the context. Consider the following contexts: + + A do expression of type (m res_ty) + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + * ExprStmt E any_ty: do { ....; E; ... } + E :: m any_ty + Translation: E >> ... + + * ResultStmt E: do { ....; E } + E :: m res_ty + Translation: E + + A list comprehensions of type [elt_ty] + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + * ExprStmt E Bool: [ .. | .... E ] + [ .. | ..., E, ... ] + [ .. | .... | ..., E | ... ] + E :: Bool + Translation: if E then fail else ... + + * ResultStmt E: [ E | ... ] + E :: elt_ty + Translation: return E + + A guard list, guarding a RHS of type rhs_ty + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + * ExprStmt E Bool: f x | ..., E, ... = ...rhs... + E :: Bool + Translation: if E then fail else ... + + * ResultStmt E: f x | ...guards... = E + E :: rhs_ty + Translation: E + +Array comprehensions are handled like list comprehensions -=chak + +\begin{code} +consLetStmt :: HsBinds id -> [Stmt id] -> [Stmt id] +consLetStmt EmptyBinds stmts = stmts +consLetStmt binds stmts = LetStmt binds : stmts +\end{code} + +\begin{code} +instance OutputableBndr id => Outputable (Stmt id) where + ppr stmt = pprStmt stmt + +pprStmt (BindStmt pat expr _) = hsep [ppr pat, ptext SLIT("<-"), ppr expr] +pprStmt (LetStmt binds) = hsep [ptext SLIT("let"), pprBinds binds] +pprStmt (ExprStmt expr _ _) = ppr expr +pprStmt (ResultStmt expr _) = ppr expr +pprStmt (ParStmt stmtss) = hsep (map (\stmts -> ptext SLIT("| ") <> ppr stmts) stmtss) +pprStmt (RecStmt segment _ _ _) = ptext SLIT("rec") <+> braces (vcat (map ppr segment)) + +pprDo :: OutputableBndr id => HsStmtContext any -> [Stmt id] -> SDoc +pprDo DoExpr stmts = hang (ptext SLIT("do")) 2 (vcat (map ppr stmts)) +pprDo MDoExpr stmts = hang (ptext SLIT("mdo")) 3 (vcat (map ppr stmts)) +pprDo ListComp stmts = pprComp brackets stmts +pprDo PArrComp stmts = pprComp pa_brackets stmts + +pprComp :: OutputableBndr id => (SDoc -> SDoc) -> [Stmt id] -> SDoc +pprComp brack stmts = brack $ + hang (pprExpr expr <+> char '|') + 4 (interpp'SP quals) + where + ResultStmt expr _ = last stmts -- Last stmt should + quals = init stmts -- be an ResultStmt +\end{code} + +%************************************************************************ +%* * + Template Haskell quotation brackets +%* * +%************************************************************************ + +\begin{code} +data HsBracket id = ExpBr (HsExpr id) + | PatBr (Pat id) + | DecBr (HsGroup id) + | TypBr (HsType id) + +instance OutputableBndr id => Outputable (HsBracket id) where + ppr = pprHsBracket + + +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) + + +thBrackets pp_kind pp_body = char '[' <> pp_kind <> char '|' <+> + pp_body <+> ptext SLIT("|]") + +data HsReify id = Reify ReifyFlavour id -- Pre typechecking + | ReifyOut ReifyFlavour Name -- Post typechecking + -- The Name could be the name of + -- an Id, TyCon, or Class + +data ReifyFlavour = ReifyDecl | ReifyType | ReifyFixity + +instance Outputable id => Outputable (HsReify id) where + ppr (Reify flavour id) = ppr flavour <+> ppr id + ppr (ReifyOut flavour thing) = ppr flavour <+> ppr thing + +instance Outputable ReifyFlavour where + ppr ReifyDecl = ptext SLIT("reifyDecl") + ppr ReifyType = ptext SLIT("reifyType") + ppr ReifyFixity = ptext SLIT("reifyFixity") \end{code} %************************************************************************ @@ -407,47 +850,114 @@ instance (NamedThing id, Outputable id, Outputable pat, %************************************************************************ \begin{code} -data ArithSeqInfo tyvar uvar id pat - = From (HsExpr tyvar uvar id pat) - | FromThen (HsExpr tyvar uvar id pat) - (HsExpr tyvar uvar id pat) - | FromTo (HsExpr tyvar uvar id pat) - (HsExpr tyvar uvar id pat) - | FromThenTo (HsExpr tyvar uvar id pat) - (HsExpr tyvar uvar id pat) - (HsExpr tyvar uvar id pat) +data ArithSeqInfo id + = From (HsExpr id) + | FromThen (HsExpr id) + (HsExpr id) + | FromTo (HsExpr id) + (HsExpr id) + | FromThenTo (HsExpr id) + (HsExpr id) + (HsExpr id) +\end{code} + +\begin{code} +instance OutputableBndr id => Outputable (ArithSeqInfo id) where + ppr (From e1) = hcat [ppr e1, pp_dotdot] + ppr (FromThen e1 e2) = hcat [ppr e1, comma, space, ppr e2, pp_dotdot] + ppr (FromTo e1 e3) = hcat [ppr e1, pp_dotdot, ppr e3] + ppr (FromThenTo e1 e2 e3) + = hcat [ppr e1, comma, space, ppr e2, pp_dotdot, ppr e3] + +pp_dotdot = ptext SLIT(" .. ") +\end{code} + + +%************************************************************************ +%* * +\subsection{HsMatchCtxt} +%* * +%************************************************************************ + +\begin{code} +data HsMatchContext id -- Context of a Match + = FunRhs id -- Function binding for f + | CaseAlt -- Guard on a case alternative + | LambdaExpr -- Pattern of a lambda + | ProcExpr -- Pattern of a proc + | PatBindRhs -- Pattern binding + | 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 () + +data HsStmtContext id + = ListComp + | DoExpr + | 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 \end{code} \begin{code} -instance (NamedThing id, Outputable id, Outputable pat, - Eq tyvar, Outputable tyvar, Eq uvar, Outputable uvar) => - Outputable (ArithSeqInfo tyvar uvar id pat) where - ppr sty (From e1) = ppBesides [ppr sty e1, pp_dotdot] - ppr sty (FromThen e1 e2) = ppBesides [ppr sty e1, pp'SP, ppr sty e2, pp_dotdot] - ppr sty (FromTo e1 e3) = ppBesides [ppr sty e1, pp_dotdot, ppr sty e3] - ppr sty (FromThenTo e1 e2 e3) - = ppBesides [ppr sty e1, pp'SP, ppr sty e2, pp_dotdot, ppr sty e3] - -pp_dotdot = ppPStr SLIT(" .. ") +isDoExpr :: HsStmtContext id -> Bool +isDoExpr DoExpr = True +isDoExpr MDoExpr = True +isDoExpr other = False \end{code} -``Qualifiers'' in list comprehensions: \begin{code} -data Qual tyvar uvar id pat - = GeneratorQual pat - (HsExpr tyvar uvar id pat) - | LetQual (HsBinds tyvar uvar id pat) - | FilterQual (HsExpr tyvar uvar id pat) +matchSeparator (FunRhs _) = ptext SLIT("=") +matchSeparator CaseAlt = ptext SLIT("->") +matchSeparator LambdaExpr = ptext SLIT("->") +matchSeparator ProcExpr = ptext SLIT("->") +matchSeparator PatBindRhs = ptext SLIT("=") +matchSeparator (StmtCtxt _) = ptext SLIT("<-") +matchSeparator RecUpd = panic "unused" \end{code} \begin{code} -instance (NamedThing id, Outputable id, Outputable pat, - Eq tyvar, Outputable tyvar, Eq uvar, Outputable uvar) => - Outputable (Qual tyvar uvar id pat) where - ppr sty (GeneratorQual pat expr) - = ppCat [ppr sty pat, ppStr "<-", ppr sty expr] - ppr sty (LetQual binds) - = ppCat [ppPStr SLIT("let"), ppr sty binds] - ppr sty (FilterQual expr) - = ppr sty expr +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 + +pprMatchRhsContext (FunRhs fun) = ptext SLIT("a right-hand side of function") <+> quotes (ppr fun) +pprMatchRhsContext CaseAlt = ptext SLIT("the body of a case alternative") +pprMatchRhsContext PatBindRhs = ptext SLIT("the right-hand side of a pattern binding") +pprMatchRhsContext LambdaExpr = ptext SLIT("the body of a lambda") +pprMatchRhsContext ProcExpr = ptext SLIT("the body of a proc") +pprMatchRhsContext RecUpd = panic "pprMatchRhsContext" + +pprStmtContext (ParStmtCtxt c) = sep [ptext SLIT("a parallel branch of"), pprStmtContext c] +pprStmtContext (PatGuard ctxt) = ptext SLIT("a pattern guard for") $$ pprMatchContext ctxt +pprStmtContext DoExpr = ptext SLIT("a 'do' expression") +pprStmtContext MDoExpr = ptext SLIT("an 'mdo' expression") +pprStmtContext ListComp = ptext SLIT("a list comprehension") +pprStmtContext PArrComp = ptext SLIT("an array comprehension") + +-- Used for the result statement of comprehension +-- e.g. the 'e' in [ e | ... ] +-- or the 'r' in f x = r +pprStmtResultContext (PatGuard ctxt) = pprMatchRhsContext ctxt +pprStmtResultContext other = ptext SLIT("the result of") <+> pprStmtContext other + + +-- Used to generate the string for a *runtime* error message +matchContextErrString (FunRhs fun) = "function " ++ showSDoc (ppr fun) +matchContextErrString CaseAlt = "case" +matchContextErrString PatBindRhs = "pattern binding" +matchContextErrString RecUpd = "record update" +matchContextErrString LambdaExpr = "lambda" +matchContextErrString ProcExpr = "proc" +matchContextErrString (StmtCtxt (ParStmtCtxt c)) = matchContextErrString (StmtCtxt c) +matchContextErrString (StmtCtxt (PatGuard _)) = "pattern guard" +matchContextErrString (StmtCtxt DoExpr) = "'do' expression" +matchContextErrString (StmtCtxt MDoExpr) = "'mdo' expression" +matchContextErrString (StmtCtxt ListComp) = "list comprehension" +matchContextErrString (StmtCtxt PArrComp) = "array comprehension" \end{code}