import HsDecls ( HsGroup )
import HsPat ( LPat )
import HsLit ( HsLit(..), HsOverLit )
-import HsTypes ( LHsType, PostTcType, SyntaxName )
+import HsTypes ( LHsType, PostTcType )
import HsImpExp ( isOperator, pprHsVar )
-import HsBinds ( HsBindGroup )
+import HsBinds ( HsBindGroup, DictBinds )
-- others:
import Type ( Type, pprParendType )
import Var ( TyVar, Id )
import Name ( Name )
-import DataCon ( DataCon )
import BasicTypes ( IPName, Boxity, tupleParens, Fixity(..) )
import SrcLoc ( Located(..), unLoc )
import Outputable
\begin{code}
type LHsExpr id = Located (HsExpr id)
+-------------------------
+-- PostTcExpr is an evidence expression attached to the
+-- syntax tree by the type checker (c.f. postTcType)
+-- We use a PostTcTable where there are a bunch of pieces of
+-- evidence, more than is convenient to keep individually
+type PostTcExpr = HsExpr Id
+type PostTcTable = [(Name, Id)]
+
+noPostTcExpr :: PostTcExpr
+noPostTcExpr = HsLit (HsString FSLIT("noPostTcExpr"))
+
+noPostTcTable :: PostTcTable
+noPostTcTable = []
+
+-------------------------
+-- SyntaxExpr is like PostTcExpr, but it's filled in a little earlier,
+-- by the renamer. It's used for rebindable syntax.
+-- 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
+
+type SyntaxExpr id = HsExpr id
+
+noSyntaxExpr :: SyntaxExpr id -- Before renaming, and sometimes after,
+ -- (if the syntax slot makes no sense)
+noSyntaxExpr = HsLit (HsString FSLIT("noSyntaxExpr"))
+
+
+type SyntaxTable id = [(Name, SyntaxExpr id)]
+-- *** Currently used only for CmdTop (sigh) ***
+-- * Before the renamer, this list is noSyntaxTable
+--
+-- * 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
+
+noSyntaxTable :: SyntaxTable id
+noSyntaxTable = []
+
+
+-------------------------
data HsExpr id
= HsVar id -- variable
| HsIPVar (IPName id) -- implicit parameter
- | HsOverLit HsOverLit -- Overloaded literals; eliminated by type checker
+ | HsOverLit (HsOverLit id) -- Overloaded literals
| HsLit HsLit -- Simple (non-overloaded) literals
| HsLam (MatchGroup id) -- Currently always a single match
-- They are eventually removed by the type checker.
| NegApp (LHsExpr id) -- negated expr
- SyntaxName -- Name of 'negate' (see RnEnv.lookupSyntaxName)
+ (SyntaxExpr id) -- Name of 'negate'
| HsPar (LHsExpr id) -- parenthesised expr
-- because in this context we never use
-- the PatGuard or ParStmt variant
[LStmt id] -- "do":one or more stmts
- (ReboundNames id) -- Ids for [return,fail,>>=,>>]
- PostTcType -- Type of the whole expression
+ (LHsExpr id) -- The body; the last expression in the 'do'
+ -- of [ body | ... ] in a list comp
+ PostTcType -- Type of the whole expression
| ExplicitList -- syntactic list
PostTcType -- Gives type of components of list
-- Record construction
- | RecordCon (Located id) -- The constructor
+ | RecordCon (Located id) -- The constructor. After type checking
+ -- it's the *worker* Id of the constructor
+ PostTcExpr -- Data con Id applied to type args
(HsRecordBinds id)
- | RecordConOut DataCon
- (LHsExpr id) -- Data con Id applied to type args
- (HsRecordBinds id)
-
-
-- Record update
| RecordUpd (LHsExpr id)
(HsRecordBinds id)
-
- | RecordUpdOut (LHsExpr id) -- TRANSLATION
- Type -- Type of *input* record
- Type -- Type of *result* record (may differ from
+ PostTcType -- Type of *input* record
+ PostTcType -- Type of *result* record (may differ from
-- type of input record)
- (HsRecordBinds id)
| ExprWithTySig -- e :: type
(LHsExpr id)
(LHsExpr id)
(LHsType Name) -- Retain the signature for round-tripping purposes
- | ArithSeqIn -- arithmetic sequence
- (ArithSeqInfo id)
- | ArithSeqOut
- (LHsExpr id) -- (typechecked, of course)
+ | ArithSeq -- arithmetic sequence
+ PostTcExpr
(ArithSeqInfo id)
- | PArrSeqIn -- arith. sequence for parallel array
- (ArithSeqInfo id) -- [:e1..e2:] or [:e1, e2..e3:]
- | PArrSeqOut
- (LHsExpr id) -- (typechecked, of course)
+
+ | PArrSeq -- arith. sequence for parallel array
+ PostTcExpr -- [:e1..e2:] or [:e1, e2..e3:]
(ArithSeqInfo id)
| HsSCC FastString -- "set cost centre" (_scc_) annotation
-- 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
@ClassDictLam dictvars methods expr@ is, therefore:
\begin{verbatim}
= 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 (HsDo do_or_list_comp stmts body _) = pprDo do_or_list_comp stmts body
ppr_expr (ExplicitList _ exprs)
= brackets (fsep (punctuate comma (map ppr_lexpr exprs)))
ppr_expr (ExplicitTuple exprs boxity)
= tupleParens boxity (sep (punctuate comma (map ppr_lexpr exprs)))
-ppr_expr (RecordCon con_id rbinds)
+ppr_expr (RecordCon con_id con_expr 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)
+ppr_expr (RecordUpd aexp rbinds _ _)
= pp_rbinds (pprParendExpr aexp) rbinds
ppr_expr (ExprWithTySig expr sig)
= hang (nest 2 (ppr_lexpr 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 (ArithSeq expr info) = brackets (ppr info)
+ppr_expr (PArrSeq expr info) = pa_brackets (ppr info)
-ppr_expr EWildPat = char '_'
+ppr_expr EWildPat = char '_'
ppr_expr (ELazyPat e) = char '~' <> pprParendExpr e
ppr_expr (EAsPat v e) = ppr v <> char '@' <> pprParendExpr e
-- 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
= HsCmdTop (LHsCmd id)
[PostTcType] -- types of inputs on the command's stack
PostTcType -- return type of the command
- (ReboundNames id)
+ (SyntaxTable id)
-- after type checking:
-- names used in the command's desugaring
\end{code}
-- Nothing after typechecking
(GRHSs id)
--- gaw 2004
hsLMatchPats :: LMatch id -> [LPat id]
hsLMatchPats (L _ (Match pats _ _)) = pats
data GRHSs id
= GRHSs [LGRHS id] -- Guarded RHSs
[HsBindGroup id] -- The where clause
--- gaw 2004
--- PostTcType -- Type of RHS (after type checking)
type LGRHS id = Located (GRHS id)
-data GRHS id
- = GRHS [LStmt id] -- The RHS is the final ResultStmt
+data GRHS id = GRHS [LStmt id] -- Guards
+ (LHsExpr id) -- Right hand side
\end{code}
We know the list must have at least one @Match@ in it.
pprMatch :: OutputableBndr id => HsMatchContext id -> Match id -> SDoc
--- gaw 2004
pprMatch ctxt (Match pats maybe_ty grhss)
= pp_name ctxt <+> sep [sep (map ppr pats),
ppr_maybe_ty,
pprGRHSs :: OutputableBndr id => HsMatchContext id -> GRHSs id -> SDoc
--- gaw 2004
pprGRHSs ctxt (GRHSs grhss binds)
= vcat (map (pprGRHS ctxt . unLoc) grhss)
$$
pprGRHS :: OutputableBndr id => HsMatchContext id -> GRHS id -> SDoc
-pprGRHS ctxt (GRHS [L _ (ResultStmt expr)])
+pprGRHS ctxt (GRHS [] expr)
= pp_rhs ctxt expr
-pprGRHS ctxt (GRHS guarded)
+pprGRHS ctxt (GRHS guards expr)
= sep [char '|' <+> interpp'SP guards, pp_rhs ctxt expr]
- where
- ResultStmt expr = unLoc (last guarded)
- -- Last stmt should be a ResultStmt for guards
- guards = init guarded
pp_rhs ctxt rhs = matchSeparator ctxt <+> pprDeeper (ppr rhs)
\end{code}
\begin{code}
type LStmt id = Located (Stmt id)
+-- The SyntaxExprs in here are used *only* for do-notation, which
+-- has rebindable syntax. Otherwise they are unused.
data Stmt id
- = BindStmt (LPat id) (LHsExpr id)
+ = BindStmt (LPat id)
+ (LHsExpr id)
+ (SyntaxExpr id) -- The (>>=) operator
+ (SyntaxExpr id) -- The fail operator
+ -- The fail operator is noSyntaxExpr
+ -- if the pattern match can't fail
+
+ | ExprStmt (LHsExpr id)
+ (SyntaxExpr id) -- The (>>) operator
+ PostTcType -- Element type of the RHS (used for arrows)
+
| LetStmt [HsBindGroup id]
- | ResultStmt (LHsExpr id) -- See notes that follow
- | ExprStmt (LHsExpr id) PostTcType -- See notes that follow
- -- The type is the *element type* of the expression
-- ParStmts only occur in a list comprehension
| ParStmt [([LStmt id], [id])] -- After remaing, the ids are the binders
-- 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
- [LHsExpr id] -- These expressions correspond
+ --- These fields are only valid after typechecking
+ [PostTcExpr] -- 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*.
+ (DictBinds id) -- Method bindings of Ids bound by the RecStmt,
+ -- and used afterwards
\end{code}
-ExprStmts and ResultStmts are a bit tricky, because what they mean
+ExprStmts are a bit tricky, because what they mean
depends on the context. Consider the following contexts:
A do expression of type (m res_ty)
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 :: 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
Note [RecStmt]
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 -> [LStmt 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) -> [LStmt id] -> SDoc
-pprComp brack stmts
+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 (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 -> [LStmt id] -> LHsExpr id -> SDoc
+pprDo DoExpr stmts body = hang (ptext SLIT("do")) 2 (vcat (map ppr stmts) $$ ppr body)
+pprDo (MDoExpr _) stmts body = hang (ptext SLIT("mdo")) 3 (vcat (map ppr stmts) $$ ppr body)
+pprDo ListComp stmts body = pprComp brackets stmts body
+pprDo PArrComp stmts body = pprComp pa_brackets stmts body
+
+pprComp :: OutputableBndr id => (SDoc -> SDoc) -> [LStmt id] -> LHsExpr id -> SDoc
+pprComp brack quals body
= brack $
- hang (ppr expr <+> char '|')
+ hang (ppr body <+> char '|')
4 (interpp'SP quals)
- where
- ResultStmt expr = unLoc (last stmts) -- Last stmt should
- quals = init stmts -- be an ResultStmt
\end{code}
%************************************************************************
data HsStmtContext id
= ListComp
| DoExpr
- | MDoExpr -- Recursive do-expression
+ | MDoExpr PostTcTable -- Recursive do-expression
+ -- (tiresomely, it needs table
+ -- of its return/bind ops)
| PArrComp -- Parallel array comprehension
| PatGuard (HsMatchContext id) -- Pattern guard for specified thing
| ParStmtCtxt (HsStmtContext id) -- A branch of a parallel stmt
\begin{code}
isDoExpr :: HsStmtContext id -> Bool
-isDoExpr DoExpr = True
-isDoExpr MDoExpr = True
-isDoExpr other = False
+isDoExpr DoExpr = True
+isDoExpr (MDoExpr _) = True
+isDoExpr other = False
\end{code}
\begin{code}
pprStmtContext (ParStmtCtxt c) = sep [ptext SLIT("a parallel branch of"), pprStmtContext c]
pprStmtContext (PatGuard ctxt) = ptext SLIT("a pattern guard for") $$ pprMatchContext ctxt
pprStmtContext DoExpr = ptext SLIT("a 'do' expression")
-pprStmtContext MDoExpr = ptext SLIT("an 'mdo' expression")
+pprStmtContext (MDoExpr _) = ptext SLIT("an 'mdo' expression")
pprStmtContext ListComp = ptext SLIT("a list comprehension")
pprStmtContext PArrComp = ptext SLIT("an array comprehension")
matchContextErrString (StmtCtxt (ParStmtCtxt c)) = matchContextErrString (StmtCtxt c)
matchContextErrString (StmtCtxt (PatGuard _)) = "pattern guard"
matchContextErrString (StmtCtxt DoExpr) = "'do' expression"
-matchContextErrString (StmtCtxt MDoExpr) = "'mdo' expression"
+matchContextErrString (StmtCtxt (MDoExpr _)) = "'mdo' expression"
matchContextErrString (StmtCtxt ListComp) = "list comprehension"
matchContextErrString (StmtCtxt PArrComp) = "array comprehension"
\end{code}
projects / ghc-hetmet.git / blobdiff