%
-% (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}
%************************************************************************
%************************************************************************
\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, <expression>)]
+-- where <expression> is the evidence for the method
\end{code}
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}
%************************************************************************
%************************************************************************
\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}
%************************************************************************
%************************************************************************
\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}
projects / ghc-hetmet.git / blobdiff