TcMatches: Typecheck some @Matches@
\begin{code}
-{-# OPTIONS -w #-}
--- The above warning supression flag is a temporary kludge.
--- While working on this module you are encouraged to remove it and fix
--- any warnings in the module. See
--- http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
--- for details
-
module TcMatches ( tcMatchesFun, tcGRHSsPat, tcMatchesCase, tcMatchLambda,
- matchCtxt, TcMatchCtxt(..),
+ TcMatchCtxt(..),
tcStmts, tcDoStmts, tcBody,
tcDoStmt, tcMDoStmt, tcGuardStmt
) where
-#include "HsVersions.h"
-
import {-# SOURCE #-} TcExpr( tcSyntaxOp, tcInferRho, tcMonoExpr, tcPolyExpr )
import HsSyn
import TcRnMonad
-import TcGadt
import Inst
import TcEnv
import TcPat
import Outputable
import Util
import SrcLoc
+import FastString
-import Control.Monad( liftM )
+import Control.Monad
\end{code}
%************************************************************************
tcMatches match_ctxt pat_tys rhs_ty matches
}
where
- doc = ptext SLIT("The equation(s) for") <+> quotes (ppr fun_name)
- <+> ptext SLIT("have") <+> speakNOf n_pats (ptext SLIT("argument"))
+ doc = ptext (sLit "The equation(s) for") <+> quotes (ppr fun_name)
+ <+> ptext (sLit "have") <+> speakNOf n_pats (ptext (sLit "argument"))
n_pats = matchGroupArity matches
match_ctxt = MC { mc_what = FunRhs fun_name inf, mc_body = tcBody }
\end{code}
tcMatches match_ctxt pat_tys rhs_ty match
where
n_pats = matchGroupArity match
- doc = sep [ ptext SLIT("The lambda expression")
+ doc = sep [ ptext (sLit "The lambda expression")
<+> quotes (pprSetDepth 1 $ pprMatches (LambdaExpr :: HsMatchContext Name) match),
-- The pprSetDepth makes the abstraction print briefly
- ptext SLIT("has") <+> speakNOf n_pats (ptext SLIT("argument"))]
+ ptext (sLit "has") <+> speakNOf n_pats (ptext (sLit "argument"))]
match_ctxt = MC { mc_what = LambdaExpr,
mc_body = tcBody }
\end{code}
\begin{code}
tcGRHSsPat :: GRHSs Name -> BoxyRhoType -> TcM (GRHSs TcId)
-- Used for pattern bindings
-tcGRHSsPat grhss res_ty = tcGRHSs match_ctxt grhss (emptyRefinement, res_ty)
- -- emptyRefinement: no refinement in a pattern binding
+tcGRHSsPat grhss res_ty = tcGRHSs match_ctxt grhss res_ty
where
match_ctxt = MC { mc_what = PatBindRhs,
mc_body = tcBody }
data TcMatchCtxt -- c.f. TcStmtCtxt, also in this module
= MC { mc_what :: HsMatchContext Name, -- What kind of thing this is
- mc_body :: LHsExpr Name -- Type checker for a body of an alternative
- -> (Refinement, BoxyRhoType)
+ mc_body :: LHsExpr Name -- Type checker for a body of
+ -- an alternative
+ -> BoxyRhoType
-> TcM (LHsExpr TcId) }
tcMatches ctxt pat_tys rhs_ty (MatchGroup matches _)
= tcGRHSs ctxt grhss rhs_ty -- No result signature
-- Result type sigs are no longer supported
- tc_grhss ctxt (Just res_sig) grhss (co, rhs_ty)
- = do { addErr (ptext SLIT("Ignoring (deprecated) result type signature")
- <+> ppr res_sig)
- ; tcGRHSs ctxt grhss (co, rhs_ty) }
+ tc_grhss _ (Just {}) _ _
+ = panic "tc_ghrss" -- Rejected by renamer
-- For (\x -> e), tcExpr has already said "In the expresssion \x->e"
-- so we don't want to add "In the lambda abstraction \x->e"
add_match_ctxt match thing_inside
= case mc_what ctxt of
LambdaExpr -> thing_inside
- m_ctxt -> addErrCtxt (matchCtxt m_ctxt match) thing_inside
+ m_ctxt -> addErrCtxt (pprMatchInCtxt m_ctxt match) thing_inside
-------------
-tcGRHSs :: TcMatchCtxt -> GRHSs Name -> (Refinement, BoxyRhoType)
+tcGRHSs :: TcMatchCtxt -> GRHSs Name -> BoxyRhoType
-> TcM (GRHSs TcId)
-- Notice that we pass in the full res_ty, so that we get
tcGRHSs ctxt (GRHSs grhss binds) res_ty
= do { (binds', grhss') <- tcLocalBinds binds $
- mappM (wrapLocM (tcGRHS ctxt res_ty)) grhss
+ mapM (wrapLocM (tcGRHS ctxt res_ty)) grhss
- ; returnM (GRHSs grhss' binds') }
+ ; return (GRHSs grhss' binds') }
-------------
-tcGRHS :: TcMatchCtxt -> (Refinement, BoxyRhoType) -> GRHS Name -> TcM (GRHS TcId)
+tcGRHS :: TcMatchCtxt -> BoxyRhoType -> GRHS Name -> TcM (GRHS TcId)
tcGRHS ctxt res_ty (GRHS guards rhs)
= do { (guards', rhs') <- tcStmts stmt_ctxt tcGuardStmt guards res_ty $
tcDoStmts ListComp stmts body res_ty
= do { (elt_ty, coi) <- boxySplitListTy res_ty
; (stmts', body') <- tcStmts ListComp (tcLcStmt listTyCon) stmts
- (emptyRefinement,elt_ty) $
+ elt_ty $
tcBody body
; return $ mkHsWrapCoI coi
(HsDo ListComp stmts' body' (mkListTy elt_ty)) }
tcDoStmts PArrComp stmts body res_ty
= do { (elt_ty, coi) <- boxySplitPArrTy res_ty
; (stmts', body') <- tcStmts PArrComp (tcLcStmt parrTyCon) stmts
- (emptyRefinement, elt_ty) $
+ elt_ty $
tcBody body
; return $ mkHsWrapCoI coi
(HsDo PArrComp stmts' body' (mkPArrTy elt_ty)) }
tcDoStmts DoExpr stmts body res_ty
= do { (stmts', body') <- tcStmts DoExpr tcDoStmt stmts
- (emptyRefinement, res_ty) $
+ res_ty $
tcBody body
; return (HsDo DoExpr stmts' body' res_ty) }
tcMonoExpr rhs (mkAppTy m_ty pat_ty)
; (stmts', body') <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts
- (emptyRefinement, res_ty') $
+ res_ty' $
tcBody body
; let names = [mfixName, bindMName, thenMName, returnMName, failMName]
mkHsWrapCoI coi
(HsDo (MDoExpr (names `zip` insts)) stmts' body' res_ty') }
-tcDoStmts ctxt stmts body res_ty = pprPanic "tcDoStmts" (pprStmtContext ctxt)
+tcDoStmts ctxt _ _ _ = pprPanic "tcDoStmts" (pprStmtContext ctxt)
-tcBody :: LHsExpr Name -> (Refinement, BoxyRhoType) -> TcM (LHsExpr TcId)
-tcBody body (reft, res_ty)
- = do { traceTc (text "tcBody" <+> ppr res_ty <+> ppr reft)
- ; let (co, res_ty') = refineResType reft res_ty
- ; body' <- tcPolyExpr body res_ty'
- ; return (mkLHsWrap co body') }
+tcBody :: LHsExpr Name -> BoxyRhoType -> TcM (LHsExpr TcId)
+tcBody body res_ty
+ = do { traceTc (text "tcBody" <+> ppr res_ty)
+ ; body' <- tcPolyExpr body res_ty
+ ; return body'
+ }
\end{code}
type TcStmtChecker
= forall thing. HsStmtContext Name
-> Stmt Name
- -> (Refinement, BoxyRhoType) -- Result type for comprehension
- -> ((Refinement,BoxyRhoType) -> TcM thing) -- Checker for what follows the stmt
+ -> BoxyRhoType -- Result type for comprehension
+ -> (BoxyRhoType -> TcM thing) -- Checker for what follows the stmt
-> TcM (Stmt TcId, thing)
- -- The incoming BoxyRhoType may be refined by type refinements
- -- before being passed to the thing_inside
-
tcStmts :: HsStmtContext Name
-> TcStmtChecker -- NB: higher-rank type
-> [LStmt Name]
- -> (Refinement, BoxyRhoType)
- -> ((Refinement, BoxyRhoType) -> TcM thing)
+ -> BoxyRhoType
+ -> (BoxyRhoType -> TcM thing)
-> TcM ([LStmt TcId], thing)
-- Note the higher-rank type. stmt_chk is applied at different
-- types in the equations for tcStmts
-tcStmts ctxt stmt_chk [] res_ty thing_inside
+tcStmts _ _ [] res_ty thing_inside
= do { thing <- thing_inside res_ty
; return ([], thing) }
tcStmts ctxt stmt_chk (L loc stmt : stmts) res_ty thing_inside
= do { (stmt', (stmts', thing)) <-
setSrcSpan loc $
- addErrCtxt (stmtCtxt ctxt stmt) $
+ addErrCtxt (pprStmtInCtxt ctxt stmt) $
stmt_chk ctxt stmt res_ty $ \ res_ty' ->
popErrCtxt $
tcStmts ctxt stmt_chk stmts res_ty' $
--------------------------------
-- Pattern guards
tcGuardStmt :: TcStmtChecker
-tcGuardStmt ctxt (ExprStmt guard _ _) res_ty thing_inside
+tcGuardStmt _ (ExprStmt guard _ _) res_ty thing_inside
= do { guard' <- tcMonoExpr guard boolTy
; thing <- thing_inside res_ty
; return (ExprStmt guard' noSyntaxExpr boolTy, thing) }
-tcGuardStmt ctxt (BindStmt pat rhs _ _) res_ty thing_inside
+tcGuardStmt _ (BindStmt pat rhs _ _) res_ty thing_inside
= do { (rhs', rhs_ty) <- tcInferRho rhs
; (pat', thing) <- tcLamPat pat rhs_ty res_ty thing_inside
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-tcGuardStmt ctxt stmt res_ty thing_inside
+tcGuardStmt _ stmt _ _
= pprPanic "tcGuardStmt: unexpected Stmt" (ppr stmt)
-> TcStmtChecker
-- A generator, pat <- rhs
-tcLcStmt m_tc ctxt (BindStmt pat rhs _ _) res_ty thing_inside
+tcLcStmt m_tc _ (BindStmt pat rhs _ _) res_ty thing_inside
= do { (rhs', pat_ty) <- withBox liftedTypeKind $ \ ty ->
tcMonoExpr rhs (mkTyConApp m_tc [ty])
; (pat', thing) <- tcLamPat pat pat_ty res_ty thing_inside
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-- A boolean guard
-tcLcStmt m_tc ctxt (ExprStmt rhs _ _) res_ty thing_inside
+tcLcStmt _ _ (ExprStmt rhs _ _) res_ty thing_inside
= do { rhs' <- tcMonoExpr rhs boolTy
; thing <- thing_inside res_ty
; return (ExprStmt rhs' noSyntaxExpr boolTy, thing) }
; return (ParStmt pairs', thing) }
where
-- loop :: [([LStmt Name], [Name])] -> TcM ([([LStmt TcId], [TcId])], thing)
- loop [] = do { thing <- thing_inside elt_ty -- No refinement from pattern
+ loop [] = do { thing <- thing_inside elt_ty
; return ([], thing) } -- matching in the branches
loop ((stmts, names) : pairs)
= do { (stmts', (ids, pairs', thing))
- <- tcStmts ctxt (tcLcStmt m_tc) stmts elt_ty $ \ elt_ty' ->
+ <- tcStmts ctxt (tcLcStmt m_tc) stmts elt_ty $ \ _elt_ty' ->
do { ids <- tcLookupLocalIds names
; (pairs', thing) <- loop pairs
; return (ids, pairs', thing) }
associateNewBinder :: TcId -> Name -> TcId
associateNewBinder oldBinder newBinder = mkLocalId newBinder (mkTyConApp m_tc [idType oldBinder])
-tcLcStmt m_tc ctxt stmt elt_ty thing_inside
+tcLcStmt _ _ stmt _ _
= pprPanic "tcLcStmt: unexpected Stmt" (ppr stmt)
--------------------------------
tcDoStmt :: TcStmtChecker
-tcDoStmt ctxt (BindStmt pat rhs bind_op fail_op) reft_res_ty@(_,res_ty) thing_inside
+tcDoStmt _ (BindStmt pat rhs bind_op fail_op) res_ty thing_inside
= do { (rhs', rhs_ty) <- tcInferRho rhs
- -- We should use type *inference* for the RHS computations, becuase of GADTs.
+ -- We should use type *inference* for the RHS computations,
+ -- becuase of GADTs.
-- do { pat <- rhs; <rest> }
-- is rather like
-- case rhs of { pat -> <rest> }
- -- We do inference on rhs, so that information about its type can be refined
- -- when type-checking the pattern.
-
- -- Deal with rebindable syntax; (>>=) :: rhs_ty -> (a -> res_ty) -> res_ty
- ; (bind_op', pat_ty) <-
+ -- We do inference on rhs, so that information about its type
+ -- can be refined when type-checking the pattern.
+
+ -- Deal with rebindable syntax:
+ -- (>>=) :: rhs_ty -> (pat_ty -> new_res_ty) -> res_ty
+ -- This level of generality is needed for using do-notation
+ -- in full generality; see Trac #1537
+ ; ((bind_op', new_res_ty), pat_ty) <-
withBox liftedTypeKind $ \ pat_ty ->
+ withBox liftedTypeKind $ \ new_res_ty ->
tcSyntaxOp DoOrigin bind_op
- (mkFunTys [rhs_ty, mkFunTy pat_ty res_ty] res_ty)
+ (mkFunTys [rhs_ty, mkFunTy pat_ty new_res_ty] res_ty)
-- If (but only if) the pattern can fail,
-- typecheck the 'fail' operator
; fail_op' <- if isIrrefutableHsPat pat
then return noSyntaxExpr
- else tcSyntaxOp DoOrigin fail_op (mkFunTy stringTy res_ty)
+ else tcSyntaxOp DoOrigin fail_op (mkFunTy stringTy new_res_ty)
- ; (pat', thing) <- tcLamPat pat pat_ty reft_res_ty thing_inside
+ ; (pat', thing) <- tcLamPat pat pat_ty new_res_ty thing_inside
; return (BindStmt pat' rhs' bind_op' fail_op', thing) }
-tcDoStmt ctxt (ExprStmt rhs then_op _) reft_res_ty@(_,res_ty) thing_inside
+tcDoStmt _ (ExprStmt rhs then_op _) res_ty thing_inside
= do { (rhs', rhs_ty) <- tcInferRho rhs
- -- Deal with rebindable syntax; (>>) :: rhs_ty -> res_ty -> res_ty
- ; then_op' <- tcSyntaxOp DoOrigin then_op
- (mkFunTys [rhs_ty, res_ty] res_ty)
+ -- Deal with rebindable syntax; (>>) :: rhs_ty -> new_res_ty -> res_ty
+ ; (then_op', new_res_ty) <-
+ withBox liftedTypeKind $ \ new_res_ty ->
+ tcSyntaxOp DoOrigin then_op
+ (mkFunTys [rhs_ty, new_res_ty] res_ty)
- ; thing <- thing_inside reft_res_ty
+ ; thing <- thing_inside new_res_ty
; return (ExprStmt rhs' then_op' rhs_ty, thing) }
-tcDoStmt ctxt stmt res_ty thing_inside
+tcDoStmt ctxt (RecStmt {}) _ _
+ = failWithTc (ptext (sLit "Illegal 'rec' stmt in") <+> pprStmtContext ctxt)
+ -- This case can't be caught in the renamer
+ -- see RnExpr.checkRecStmt
+
+tcDoStmt _ stmt _ _
= pprPanic "tcDoStmt: unexpected Stmt" (ppr stmt)
--------------------------------
tcMDoStmt :: (LHsExpr Name -> TcM (LHsExpr TcId, TcType)) -- RHS inference
-> TcStmtChecker
-tcMDoStmt tc_rhs ctxt (BindStmt pat rhs bind_op fail_op) res_ty thing_inside
+tcMDoStmt tc_rhs _ (BindStmt pat rhs _ _) res_ty thing_inside
= do { (rhs', pat_ty) <- tc_rhs rhs
; (pat', thing) <- tcLamPat pat pat_ty res_ty thing_inside
; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
-tcMDoStmt tc_rhs ctxt (ExprStmt rhs then_op _) res_ty thing_inside
+tcMDoStmt tc_rhs _ (ExprStmt rhs _ _) res_ty thing_inside
= do { (rhs', elt_ty) <- tc_rhs rhs
; thing <- thing_inside res_ty
; return (ExprStmt rhs' noSyntaxExpr elt_ty, thing) }
; let rec_ids = zipWith mkLocalId recNames rec_tys
; tcExtendIdEnv rec_ids $ do
{ (stmts', (later_ids, rec_rets))
- <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts res_ty $ \ res_ty' ->
+ <- tcStmts ctxt (tcMDoStmt tc_rhs) stmts res_ty $ \ _res_ty' ->
-- ToDo: res_ty not really right
do { rec_rets <- zipWithM tc_ret recNames rec_tys
; later_ids <- tcLookupLocalIds laterNames
; co_fn <- tcSubExp DoOrigin (idType poly_id) mono_ty
; return (mkHsWrap co_fn (HsVar poly_id)) }
-tcMDoStmt tc_rhs ctxt stmt res_ty thing_inside
+tcMDoStmt _ _ stmt _ _
= pprPanic "tcMDoStmt: unexpected Stmt" (ppr stmt)
\end{code}
checkArgs fun (MatchGroup (match1:matches) _)
| null bad_matches = return ()
| otherwise
- = failWithTc (vcat [ptext SLIT("Equations for") <+> quotes (ppr fun) <+>
- ptext SLIT("have different numbers of arguments"),
+ = failWithTc (vcat [ptext (sLit "Equations for") <+> quotes (ppr fun) <+>
+ ptext (sLit "have different numbers of arguments"),
nest 2 (ppr (getLoc match1)),
nest 2 (ppr (getLoc (head bad_matches)))])
where
args_in_match :: LMatch Name -> Int
args_in_match (L _ (Match pats _ _)) = length pats
-checkArgs fun other = panic "TcPat.checkArgs" -- Matches always non-empty
+checkArgs _ _ = panic "TcPat.checkArgs" -- Matches always non-empty
\end{code}
-\begin{code}
-matchCtxt ctxt match = hang (ptext SLIT("In") <+> pprMatchContext ctxt <> colon)
- 4 (pprMatch ctxt match)
-
-stmtCtxt ctxt stmt = hang (ptext SLIT("In") <+> pprStmtContext ctxt <> colon)
- 4 (ppr stmt)
-\end{code}
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