#include "HsVersions.h"
-- friends:
-import {-# SOURCE #-} HsMatches ( pprMatches, pprMatch, Match )
-
-import HsBinds ( HsBinds(..) )
-import HsBasic ( HsLit )
-import BasicTypes ( Fixity(..), FixityDirection(..) )
+import HsBinds ( HsBinds(..), nullBinds )
+import HsTypes ( PostTcType )
+import HsLit ( HsLit, HsOverLit )
+import BasicTypes ( Fixity(..) )
import HsTypes ( HsType )
+import HsImpExp ( isOperator )
-- others:
-import Name ( Name, isLexSym )
+import Name ( Name )
+import ForeignCall ( Safety )
import Outputable
-import PprType ( pprType, pprParendType )
-import Type ( Type )
-import Var ( TyVar, Id )
+import PprType ( pprParendType )
+import Type ( Type )
+import Var ( TyVar )
import DataCon ( DataCon )
import CStrings ( CLabelString, pprCLabelString )
-import BasicTypes ( Boxity, tupleParens )
+import BasicTypes ( IPName, Boxity, tupleParens )
import SrcLoc ( SrcLoc )
\end{code}
\begin{code}
data HsExpr id pat
- = HsVar id -- variable
- | HsIPVar id -- implicit parameter
- | HsLit HsLit -- literal
- | HsLitOut HsLit -- TRANSLATION
- Type -- (with its type)
+ = HsVar id -- variable
+ | HsIPVar (IPName id) -- implicit parameter
+ | HsOverLit HsOverLit -- Overloaded literals; eliminated by type checker
+ | HsLit HsLit -- Simple (non-overloaded) literals
| HsLam (Match id pat) -- lambda
| HsApp (HsExpr id pat) -- application
-- They are eventually removed by the type checker.
| NegApp (HsExpr id pat) -- negated expr
- (HsExpr id pat) -- the negate id (in a HsVar)
+ Name -- Name of 'negate' (see RnEnv.lookupSyntaxName)
| HsPar (HsExpr id pat) -- parenthesised expr
(HsExpr id pat)
| HsWith (HsExpr id pat) -- implicit parameter binding
- [(id, HsExpr id pat)]
+ [(IPName id, HsExpr id pat)]
- | HsDo StmtCtxt
+ | HsDo HsDoContext
[Stmt id pat] -- "do":one or more stmts
SrcLoc
- | HsDoOut StmtCtxt
+ | HsDoOut HsDoContext
[Stmt id pat] -- "do":one or more stmts
id -- id for return
id -- id for >>=
- id -- id for zero
+ id -- id for fail
Type -- Type of the whole expression
SrcLoc
| ExplicitList -- syntactic list
- [HsExpr id pat]
- | ExplicitListOut -- TRANSLATION
- Type -- Gives type of components of list
+ PostTcType -- Gives type of components of list
[HsExpr id pat]
| ExplicitTuple -- tuple
(HsRecordBinds id pat)
| RecordUpdOut (HsExpr id pat) -- TRANSLATION
+ Type -- Type of *input* record
Type -- Type of *result* record (may differ from
- -- type of input record)
+ -- type of input record)
[id] -- Dicts needed for construction
(HsRecordBinds id pat)
| HsCCall CLabelString -- call into the C world; string is
[HsExpr id pat] -- 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#".
- Type -- 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 id pat) -- expr whose cost is to be measured
+
\end{code}
These constructors only appear temporarily in the parser.
(HsExpr id pat)
| ELazyPat (HsExpr id pat) -- ~ pattern
+
+ | HsType (HsType id) -- Explicit type argument; e.g f {| Int |} x y
\end{code}
Everything from here on appears only in typechecker output.
| isOperator v = parens (ppr v)
| otherwise = ppr v
-ppr_expr (HsIPVar v) = {- char '?' <> -} ppr v
-
-ppr_expr (HsLit lit) = ppr lit
-ppr_expr (HsLitOut lit _) = ppr lit
+ppr_expr (HsIPVar v) = ppr v
+ppr_expr (HsLit lit) = ppr lit
+ppr_expr (HsOverLit lit) = ppr lit
ppr_expr (HsLam match)
- = hsep [char '\\', nest 2 (pprMatch (True,empty) match)]
+ = hsep [char '\\', nest 2 (pprMatch LambdaExpr match)]
ppr_expr expr@(HsApp e1 e2)
= let (fun, args) = collect_args expr [] in
| otherwise = char '`' <> ppr v <> char '`'
-- Put it in backquotes if it's not an operator already
-ppr_expr (NegApp e _)
- = char '-' <+> pprParendExpr e
+ppr_expr (NegApp e _) = char '-' <+> pprParendExpr e
ppr_expr (HsPar e) = parens (ppr_expr e)
ppr_expr (HsCase expr matches _)
= sep [ sep [ptext SLIT("case"), nest 4 (pprExpr expr), ptext SLIT("of")],
- nest 2 (pprMatches (True, empty) matches) ]
+ nest 2 (pprMatches CaseAlt matches) ]
ppr_expr (HsIf e1 e2 e3 _)
= sep [hsep [ptext SLIT("if"), nest 2 (pprExpr e1), ptext SLIT("then")],
hang (ptext SLIT("in")) 2 (ppr expr)]
ppr_expr (HsWith expr binds)
- = hsep [ppr expr, ptext SLIT("with"), ppr binds]
+ = hsep [ppr expr, ptext SLIT("with"), pp_ipbinds binds]
ppr_expr (HsDo do_or_list_comp stmts _) = pprDo do_or_list_comp stmts
ppr_expr (HsDoOut do_or_list_comp stmts _ _ _ _ _) = pprDo do_or_list_comp stmts
-ppr_expr (ExplicitList exprs)
+ppr_expr (ExplicitList _ exprs)
= brackets (fsep (punctuate comma (map ppr_expr exprs)))
-ppr_expr (ExplicitListOut ty exprs)
- = hcat [ brackets (fsep (punctuate comma (map ppr_expr exprs))),
- ifNotPprForUser ((<>) space (parens (pprType ty))) ]
ppr_expr (ExplicitTuple exprs boxity)
= tupleParens boxity (sep (punctuate comma (map ppr_expr exprs)))
ppr_expr (RecordUpd aexp rbinds)
= pp_rbinds (pprParendExpr aexp) rbinds
-ppr_expr (RecordUpdOut aexp _ _ rbinds)
+ppr_expr (RecordUpdOut aexp _ _ _ rbinds)
= pp_rbinds (pprParendExpr aexp) rbinds
ppr_expr (ExprWithTySig expr sig)
= hang (ppr_expr expr)
4 (brackets (interpp'SP dnames))
+ppr_expr (HsType id) = ppr id
+
\end{code}
Parenthesize unless very simple:
in
case expr of
HsLit l -> ppr l
- HsLitOut l _ -> ppr l
+ HsOverLit l -> ppr l
HsVar _ -> pp_as_was
HsIPVar _ -> pp_as_was
- ExplicitList _ -> pp_as_was
- ExplicitListOut _ _ -> pp_as_was
+ ExplicitList _ _ -> pp_as_was
ExplicitTuple _ _ -> pp_as_was
HsPar _ -> pp_as_was
_ -> parens pp_as_was
\end{code}
-\begin{code}
-isOperator :: Outputable a => a -> Bool
-isOperator v = isLexSym (_PK_ (showSDoc (ppr v)))
- -- We use (showSDoc (ppr v)), rather than isSymOcc (getOccName v) simply so
- -- that we don't need NamedThing in the context of all these functions.
- -- Gruesome, but simple.
-\end{code}
-
%************************************************************************
%* *
\subsection{Record binds}
hsep [ppr v, char '=', ppr e]
\end{code}
+\begin{code}
+pp_ipbinds :: (Outputable id, Outputable pat)
+ => [(IPName id, HsExpr id pat)] -> SDoc
+pp_ipbinds pairs = hsep (punctuate semi (map pp_item pairs))
+ where
+ pp_item (id,rhs) = ppr id <+> equals <+> ppr_expr rhs
+\end{code}
+
+
%************************************************************************
%* *
-\subsection{Do stmts and list comprehensions}
+\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 StmtCtxt -- Context of a Stmt
- = DoStmt -- Do Statment
- | ListComp -- List comprehension
- | CaseAlt -- Guard on a case alternative
- | PatBindRhs -- Guard on a pattern binding
- | FunRhs Name -- Guard on a function defn for f
- | LambdaBody -- Body of a lambda abstraction
-
-pprDo DoStmt stmts
- = hang (ptext SLIT("do")) 2 (vcat (map ppr stmts))
-pprDo ListComp stmts
- = brackets $
- hang (pprExpr expr <+> char '|')
- 4 (interpp'SP quals)
+data Match id pat
+ = Match
+ [pat] -- The patterns
+ (Maybe (HsType id)) -- A type signature for the result of the match
+ -- Nothing after typechecking
+
+ (GRHSs id pat)
+
+-- GRHSs are used both for pattern bindings and for Matches
+data GRHSs id pat
+ = GRHSs [GRHS id pat] -- Guarded RHSs
+ (HsBinds id pat) -- The where clause
+ PostTcType -- Type of RHS (after type checking)
+
+data GRHS id pat
+ = GRHS [Stmt id pat] -- The RHS is the final ResultStmt
+ -- I considered using a RetunStmt, but
+ -- it printed 'wrong' in error messages
+ SrcLoc
+
+mkSimpleMatch :: [pat] -> HsExpr id pat -> Type -> SrcLoc -> Match id pat
+mkSimpleMatch pats rhs rhs_ty locn
+ = Match pats Nothing (GRHSs (unguardedRHS rhs locn) EmptyBinds rhs_ty)
+
+unguardedRHS :: HsExpr id pat -> SrcLoc -> [GRHS id pat]
+unguardedRHS rhs loc = [GRHS [ResultStmt rhs loc] loc]
+\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}
+getMatchLoc :: Match id pat -> SrcLoc
+getMatchLoc (Match _ _ (GRHSs (GRHS _ loc : _) _ _)) = loc
+\end{code}
+
+We know the list must have at least one @Match@ in it.
+
+\begin{code}
+pprMatches :: (Outputable id, Outputable pat)
+ => HsMatchContext id -> [Match id pat] -> SDoc
+pprMatches ctxt matches = vcat (map (pprMatch ctxt) matches)
+
+-- Exported to HsBinds, which can't see the defn of HsMatchContext
+pprFunBind :: (Outputable id, Outputable pat)
+ => id -> [Match id pat] -> SDoc
+pprFunBind fun matches = pprMatches (FunRhs fun) matches
+
+-- Exported to HsBinds, which can't see the defn of HsMatchContext
+pprPatBind :: (Outputable id, Outputable pat)
+ => pat -> GRHSs id pat -> SDoc
+pprPatBind pat grhss = sep [ppr pat, nest 4 (pprGRHSs PatBindRhs grhss)]
+
+
+pprMatch :: (Outputable id, Outputable pat)
+ => HsMatchContext id -> Match id pat -> 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
- ReturnStmt expr = last stmts -- Last stmt should be a ReturnStmt for list comps
- quals = init stmts
+ pp_name (FunRhs fun) = ppr fun
+ pp_name other = empty
+ ppr_maybe_ty = case maybe_ty of
+ Just ty -> dcolon <+> ppr ty
+ Nothing -> empty
+
+
+pprGRHSs :: (Outputable id, Outputable pat)
+ => HsMatchContext id -> GRHSs id pat -> 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 :: (Outputable id, Outputable pat)
+ => HsMatchContext id -> GRHS id pat -> 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 = ptext (matchSeparator ctxt) <+> pprDeeper (ppr rhs)
\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{Do stmts and list comprehensions}
+%* *
+%************************************************************************
+
\begin{code}
data Stmt id pat
- = BindStmt pat
- (HsExpr id pat)
- SrcLoc
-
+ = BindStmt pat (HsExpr id pat) SrcLoc
| LetStmt (HsBinds id pat)
+ | ResultStmt (HsExpr id pat) SrcLoc -- See notes that follow
+ | ExprStmt (HsExpr id pat) PostTcType SrcLoc -- See notes that follow
+ -- The type is the *element type* of the expression
+ | ParStmt [[Stmt id pat]] -- List comp only: parallel set of quals
+ | ParStmtOut [([id], [Stmt id pat])] -- PLC after renaming; the ids are the binders
+ -- bound by the stmts
+\end{code}
- | GuardStmt (HsExpr id pat) -- List comps only
- SrcLoc
-
- | ExprStmt (HsExpr id pat) -- Do stmts; and guarded things at the end
- SrcLoc
+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
- | ReturnStmt (HsExpr id pat) -- List comps only, at the end
+\begin{code}
consLetStmt :: HsBinds id pat -> [Stmt id pat] -> [Stmt id pat]
consLetStmt EmptyBinds stmts = stmts
consLetStmt binds stmts = LetStmt binds : stmts
Outputable (Stmt id pat) 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 (GuardStmt expr _)
- = ppr expr
-pprStmt (ReturnStmt expr)
- = hsep [ptext SLIT("return"), ppr expr]
+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 (ParStmtOut stmtss)
+ = hsep (map (\stmts -> ptext SLIT("| ") <> ppr stmts) stmtss)
+
+pprDo :: (Outputable id, Outputable pat) => HsDoContext -> [Stmt id pat] -> SDoc
+pprDo DoExpr stmts = hang (ptext SLIT("do")) 2 (vcat (map ppr stmts))
+pprDo ListComp stmts = brackets $
+ hang (pprExpr expr <+> char '|')
+ 4 (interpp'SP quals)
+ where
+ ResultStmt expr _ = last stmts -- Last stmt should
+ quals = init stmts -- be an ResultStmt
\end{code}
%************************************************************************
pp_dotdot = ptext SLIT(" .. ")
\end{code}
+
+
+%************************************************************************
+%* *
+\subsection{HsMatchCtxt}
+%* *
+%************************************************************************
+
+\begin{code}
+data HsMatchContext id -- Context of a Match or Stmt
+ = DoCtxt HsDoContext -- Do-stmt or list comprehension
+ | FunRhs id -- Function binding for f
+ | CaseAlt -- Guard on a case alternative
+ | LambdaExpr -- Lambda
+ | PatBindRhs -- Pattern binding
+ | RecUpd -- Record update
+ deriving ()
+
+data HsDoContext = ListComp | DoExpr
+\end{code}
+
+\begin{code}
+isDoExpr (DoCtxt DoExpr) = True
+isDoExpr other = False
+\end{code}
+
+\begin{code}
+matchSeparator (FunRhs _) = SLIT("=")
+matchSeparator CaseAlt = SLIT("->")
+matchSeparator LambdaExpr = SLIT("->")
+matchSeparator PatBindRhs = SLIT("=")
+matchSeparator (DoCtxt _) = SLIT("<-")
+matchSeparator RecUpd = panic "When is this used?"
+\end{code}
+
+\begin{code}
+pprMatchContext (FunRhs fun) = ptext SLIT("In the definition of") <+> quotes (ppr fun)
+pprMatchContext CaseAlt = ptext SLIT("In a case alternative")
+pprMatchContext RecUpd = ptext SLIT("In a record-update construct")
+pprMatchContext PatBindRhs = ptext SLIT("In a pattern binding")
+pprMatchContext LambdaExpr = ptext SLIT("In a lambda abstraction")
+pprMatchContext (DoCtxt DoExpr) = ptext SLIT("In a 'do' expression pattern binding")
+pprMatchContext (DoCtxt ListComp) = ptext SLIT("In a 'list comprehension' pattern binding")
+
+-- 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 (DoCtxt DoExpr) = "'do' expression"
+matchContextErrString (DoCtxt ListComp) = "list comprehension"
+\end{code}
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