Typecheck arrow notation
\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 TcArrows ( tcProc ) where
-#include "HsVersions.h"
-
-import {-# SOURCE #-} TcExpr( tcMonoExpr, tcInferRho )
+import {-# SOURCE #-} TcExpr( tcMonoExpr, tcInferRho, tcSyntaxOp, tcCheckId )
import HsSyn
-import TcHsSyn
-
import TcMatches
-
import TcType
import TcMType
import TcBinds
-import TcSimplify
-import TcGadt
import TcPat
import TcUnify
import TcRnMonad
+import TcEnv
import Coercion
+import Id( mkLocalId )
import Inst
import Name
import TysWiredIn
import VarSet
import TysPrim
-import Type
import SrcLoc
import Outputable
+import FastString
import Util
import Control.Monad
\begin{code}
tcProc :: InPat Name -> LHsCmdTop Name -- proc pat -> expr
- -> BoxyRhoType -- Expected type of whole proc expression
- -> TcM (OutPat TcId, LHsCmdTop TcId, CoercionI)
+ -> TcRhoType -- Expected type of whole proc expression
+ -> TcM (OutPat TcId, LHsCmdTop TcId, Coercion)
tcProc pat cmd exp_ty
= newArrowScope $
- do { ((exp_ty1, res_ty), coi) <- boxySplitAppTy exp_ty
- ; ((arr_ty, arg_ty), coi1) <- boxySplitAppTy exp_ty1
+ do { (coi, (exp_ty1, res_ty)) <- matchExpectedAppTy exp_ty
+ ; (coi1, (arr_ty, arg_ty)) <- matchExpectedAppTy exp_ty1
; let cmd_env = CmdEnv { cmd_arr = arr_ty }
- ; (pat', cmd') <- tcProcPat pat arg_ty (emptyRefinement, res_ty) $
- tcCmdTop cmd_env cmd []
- ; let res_coi = mkTransCoI coi (mkAppTyCoI exp_ty1 coi1 res_ty IdCo)
- ; return (pat', cmd', res_coi)
- }
+ ; (pat', cmd') <- tcPat ProcExpr pat arg_ty $
+ tcCmdTop cmd_env cmd [] res_ty
+ ; let res_coi = mkTransCo coi (mkAppCo coi1 (mkReflCo res_ty))
+ ; return (pat', cmd', res_coi) }
\end{code}
tcCmdTop :: CmdEnv
-> LHsCmdTop Name
-> CmdStack
- -> (Refinement, TcTauType) -- Expected result type; always a monotype
- -- We know exactly how many cmd args are expected,
- -- albeit perhaps not their types; so we can pass
- -- in a CmdStack
+ -> TcTauType -- Expected result type; always a monotype
+ -- We know exactly how many cmd args are expected,
+ -- albeit perhaps not their types; so we can pass
+ -- in a CmdStack
-> TcM (LHsCmdTop TcId)
-tcCmdTop env (L loc (HsCmdTop cmd _ _ names)) cmd_stk reft_res_ty@(_,res_ty)
+tcCmdTop env (L loc (HsCmdTop cmd _ _ names)) cmd_stk res_ty
= setSrcSpan loc $
- do { cmd' <- tcGuardedCmd env cmd cmd_stk reft_res_ty
+ do { cmd' <- tcCmd env cmd (cmd_stk, res_ty)
; names' <- mapM (tcSyntaxName ProcOrigin (cmd_arr env)) names
; return (L loc $ HsCmdTop cmd' cmd_stk res_ty names') }
----------------------------------------
-tcGuardedCmd :: CmdEnv -> LHsExpr Name -> CmdStack
- -> (Refinement, TcTauType) -> TcM (LHsExpr TcId)
--- A wrapper that deals with the refinement (if any)
-tcGuardedCmd env expr stk (reft, res_ty)
- = do { let (co, res_ty') = refineResType reft res_ty
- ; body <- tcCmd env expr (stk, res_ty')
- ; return (mkLHsWrap co body) }
-
tcCmd :: CmdEnv -> LHsExpr Name -> (CmdStack, TcTauType) -> TcM (LHsExpr TcId)
-- The main recursive function
tcCmd env (L loc expr) res_ty
{ expr' <- tc_cmd env expr res_ty
; return (L loc expr') }
+tc_cmd :: CmdEnv -> HsExpr Name -> (CmdStack, TcTauType) -> TcM (HsExpr TcId)
tc_cmd env (HsPar cmd) res_ty
= do { cmd' <- tcCmd env cmd res_ty
; return (HsPar cmd') }
tc_cmd env in_cmd@(HsCase scrut matches) (stk, res_ty)
= addErrCtxt (cmdCtxt in_cmd) $ do
- (scrut', scrut_ty) <- addErrCtxt (caseScrutCtxt scrut) $
- tcInferRho scrut
+ (scrut', scrut_ty) <- tcInferRho scrut
matches' <- tcMatchesCase match_ctxt scrut_ty matches res_ty
return (HsCase scrut' matches')
where
match_ctxt = MC { mc_what = CaseAlt,
mc_body = mc_body }
- mc_body body res_ty' = tcGuardedCmd env body stk res_ty'
-
-tc_cmd env (HsIf pred b1 b2) res_ty
- = do { pred' <- tcMonoExpr pred boolTy
- ; b1' <- tcCmd env b1 res_ty
- ; b2' <- tcCmd env b2 res_ty
- ; return (HsIf pred' b1' b2')
+ mc_body body res_ty' = tcCmd env body (stk, res_ty')
+
+tc_cmd env (HsIf mb_fun pred b1 b2) (stack_ty,res_ty)
+ = do { pred_ty <- newFlexiTyVarTy openTypeKind
+ ; b_ty <- newFlexiTyVarTy openTypeKind
+ ; let if_ty = mkFunTys [pred_ty, b_ty, b_ty] res_ty
+ ; mb_fun' <- case mb_fun of
+ Nothing -> return Nothing
+ Just fun -> liftM Just (tcSyntaxOp IfOrigin fun if_ty)
+ ; pred' <- tcMonoExpr pred pred_ty
+ ; b1' <- tcCmd env b1 (stack_ty,b_ty)
+ ; b2' <- tcCmd env b2 (stack_ty,b_ty)
+ ; return (HsIf mb_fun' pred' b1' b2')
}
-------------------------------------------
tc_cmd env cmd@(HsApp fun arg) (cmd_stk, res_ty)
= addErrCtxt (cmdCtxt cmd) $
--- gaw 2004 FIX?
do { arg_ty <- newFlexiTyVarTy openTypeKind
; fun' <- tcCmd env fun (arg_ty:cmd_stk, res_ty)
-------------------------------------------
-- Lambda
-tc_cmd env cmd@(HsLam (MatchGroup [L mtch_loc (match@(Match pats maybe_rhs_sig grhss))] _))
+tc_cmd env cmd@(HsLam (MatchGroup [L mtch_loc (match@(Match pats _maybe_rhs_sig grhss))] _))
(cmd_stk, res_ty)
- = addErrCtxt (matchCtxt match_ctxt match) $
+ = addErrCtxt (pprMatchInCtxt match_ctxt match) $
do { -- Check the cmd stack is big enough
; checkTc (lengthAtLeast cmd_stk n_pats)
-- Check the patterns, and the GRHSs inside
; (pats', grhss') <- setSrcSpan mtch_loc $
- tcLamPats pats cmd_stk res_ty $
- tc_grhss grhss
+ tcPats LambdaExpr pats cmd_stk $
+ tc_grhss grhss res_ty
; let match' = L mtch_loc (Match pats' Nothing grhss')
; return (HsLam (MatchGroup [match'] res_ty))
; return (GRHSs grhss' binds') }
tc_grhs res_ty (GRHS guards body)
- = do { (guards', rhs') <- tcStmts pg_ctxt tcGuardStmt guards res_ty $
- tcGuardedCmd env body stk'
+ = do { (guards', rhs') <- tcStmtsAndThen pg_ctxt tcGuardStmt guards res_ty $
+ \ res_ty -> tcCmd env body (stk', res_ty)
; return (GRHS guards' rhs') }
-------------------------------------------
-- Do notation
-tc_cmd env cmd@(HsDo do_or_lc stmts body ty) (cmd_stk, res_ty)
+tc_cmd env cmd@(HsDo do_or_lc stmts _) (cmd_stk, res_ty)
= do { checkTc (null cmd_stk) (nonEmptyCmdStkErr cmd)
- ; (stmts', body') <- tcStmts do_or_lc tc_stmt stmts (emptyRefinement, res_ty) $
- tcGuardedCmd env body []
- ; return (HsDo do_or_lc stmts' body' res_ty) }
+ ; stmts' <- tcStmts do_or_lc (tcArrDoStmt env) stmts res_ty
+ ; return (HsDo do_or_lc stmts' res_ty) }
where
- tc_stmt = tcMDoStmt tc_rhs
- tc_rhs rhs = do { ty <- newFlexiTyVarTy liftedTypeKind
- ; rhs' <- tcCmd env rhs ([], ty)
- ; return (rhs', ty) }
-----------------------------------------------------------------
tc_cmd env cmd@(HsArrForm expr fixity cmd_args) (cmd_stk, res_ty)
= addErrCtxt (cmdCtxt cmd) $
do { cmds_w_tys <- zipWithM new_cmd_ty cmd_args [1..]
- ; span <- getSrcSpanM
- ; [w_tv] <- tcInstSkolTyVars ArrowSkol [alphaTyVar]
+ ; [w_tv] <- tcInstSkolTyVars [alphaTyVar]
; let w_ty = mkTyVarTy w_tv -- Just a convenient starting point
-- a ((w,t1) .. tn) t
e_res_ty
-- Check expr
- ; (expr', lie) <- escapeArrowScope (getLIE (tcMonoExpr expr e_ty))
- ; loc <- getInstLoc (SigOrigin ArrowSkol)
- ; inst_binds <- tcSimplifyCheck loc [w_tv] [] lie
-
- -- Check that the polymorphic variable hasn't been unified with anything
- -- and is not free in res_ty or the cmd_stk (i.e. t, t1..tn)
- ; checkSigTyVarsWrt (tyVarsOfTypes (res_ty:cmd_stk)) [w_tv]
+ ; (inst_binds, expr') <- checkConstraints ArrowSkol [w_tv] [] $
+ escapeArrowScope (tcMonoExpr expr e_ty)
-- OK, now we are in a position to unscramble
-- the s1..sm and check each cmd
; cmds' <- mapM (tc_cmd w_tv) cmds_w_tys
- ; return (HsArrForm (noLoc $ HsWrap (WpTyLam w_tv)
- (unLoc $ mkHsDictLet inst_binds expr'))
- fixity cmds')
- }
+ ; let wrap = WpTyLam w_tv <.> mkWpLet inst_binds
+ ; return (HsArrForm (mkLHsWrap wrap expr') fixity cmds') }
where
-- Make the types
-- b, ((e,s1) .. sm), s
-- Check that it has the right shape:
-- ((w,s1) .. sn)
-- where the si do not mention w
- ; checkTc (corner_ty `tcEqType` mkTyVarTy w_tv &&
+ ; checkTc (corner_ty `eqType` mkTyVarTy w_tv &&
not (w_tv `elemVarSet` tyVarsOfTypes arg_tys))
(badFormFun i tup_ty')
- ; tcCmdTop (env { cmd_arr = b }) cmd arg_tys (emptyRefinement, s) }
+ ; tcCmdTop (env { cmd_arr = b }) cmd arg_tys s }
unscramble :: TcType -> (TcType, [TcType])
-- unscramble ((w,s1) .. sn) = (w, [s1..sn])
- unscramble ty
+ unscramble ty = unscramble' ty []
+
+ unscramble' ty ss
= case tcSplitTyConApp_maybe ty of
Just (tc, [t,s]) | tc == pairTyCon
- -> let
- (w,ss) = unscramble t
- in (w, s:ss)
-
- other -> (ty, [])
+ -> unscramble' t (s:ss)
+ _ -> (ty, ss)
-----------------------------------------------------------------
-- Base case for illegal commands
-- This is where expressions that aren't commands get rejected
-tc_cmd env cmd _
- = failWithTc (vcat [ptext SLIT("The expression"), nest 2 (ppr cmd),
- ptext SLIT("was found where an arrow command was expected")])
+tc_cmd _ cmd _
+ = failWithTc (vcat [ptext (sLit "The expression"), nest 2 (ppr cmd),
+ ptext (sLit "was found where an arrow command was expected")])
+\end{code}
+
+
+%************************************************************************
+%* *
+ Stmts
+%* *
+%************************************************************************
+
+\begin{code}
+--------------------------------
+-- Mdo-notation
+-- The distinctive features here are
+-- (a) RecStmts, and
+-- (b) no rebindable syntax
+
+tcArrDoStmt :: CmdEnv -> TcStmtChecker
+tcArrDoStmt env _ (LastStmt rhs _) res_ty thing_inside
+ = do { rhs' <- tcCmd env rhs ([], res_ty)
+ ; thing <- thing_inside (panic "tcArrDoStmt")
+ ; return (LastStmt rhs' noSyntaxExpr, thing) }
+
+tcArrDoStmt env _ (ExprStmt rhs _ _ _) res_ty thing_inside
+ = do { (rhs', elt_ty) <- tc_arr_rhs env rhs
+ ; thing <- thing_inside res_ty
+ ; return (ExprStmt rhs' noSyntaxExpr noSyntaxExpr elt_ty, thing) }
+
+tcArrDoStmt env ctxt (BindStmt pat rhs _ _) res_ty thing_inside
+ = do { (rhs', pat_ty) <- tc_arr_rhs env rhs
+ ; (pat', thing) <- tcPat (StmtCtxt ctxt) pat pat_ty $
+ thing_inside res_ty
+ ; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
+
+tcArrDoStmt env ctxt (RecStmt { recS_stmts = stmts, recS_later_ids = laterNames
+ , recS_rec_ids = recNames }) res_ty thing_inside
+ = do { rec_tys <- newFlexiTyVarTys (length recNames) liftedTypeKind
+ ; let rec_ids = zipWith mkLocalId recNames rec_tys
+ ; tcExtendIdEnv rec_ids $ do
+ { (stmts', (later_ids, rec_rets))
+ <- tcStmtsAndThen ctxt (tcArrDoStmt env) stmts res_ty $ \ _res_ty' ->
+ -- ToDo: res_ty not really right
+ do { rec_rets <- zipWithM tcCheckId recNames rec_tys
+ ; later_ids <- tcLookupLocalIds laterNames
+ ; return (later_ids, rec_rets) }
+
+ ; thing <- tcExtendIdEnv later_ids (thing_inside res_ty)
+ -- NB: The rec_ids for the recursive things
+ -- already scope over this part. This binding may shadow
+ -- some of them with polymorphic things with the same Name
+ -- (see note [RecStmt] in HsExpr)
+
+ ; return (emptyRecStmt { recS_stmts = stmts', recS_later_ids = later_ids
+ , recS_rec_ids = rec_ids, recS_rec_rets = rec_rets
+ , recS_ret_ty = res_ty }, thing)
+ }}
+
+tcArrDoStmt _ _ stmt _ _
+ = pprPanic "tcArrDoStmt: unexpected Stmt" (ppr stmt)
+
+tc_arr_rhs :: CmdEnv -> LHsExpr Name -> TcM (LHsExpr TcId, TcType)
+tc_arr_rhs env rhs = do { ty <- newFlexiTyVarTy liftedTypeKind
+ ; rhs' <- tcCmd env rhs ([], ty)
+ ; return (rhs', ty) }
\end{code}
\begin{code}
+mkPairTy :: Type -> Type -> Type
mkPairTy t1 t2 = mkTyConApp pairTyCon [t1,t2]
arrowTyConKind :: Kind -- *->*->*
%************************************************************************
\begin{code}
-cmdCtxt cmd = ptext SLIT("In the command:") <+> ppr cmd
-
-caseScrutCtxt cmd
- = hang (ptext SLIT("In the scrutinee of a case command:")) 4 (ppr cmd)
+cmdCtxt :: HsExpr Name -> SDoc
+cmdCtxt cmd = ptext (sLit "In the command:") <+> ppr cmd
+nonEmptyCmdStkErr :: HsExpr Name -> SDoc
nonEmptyCmdStkErr cmd
- = hang (ptext SLIT("Non-empty command stack at command:"))
- 4 (ppr cmd)
+ = hang (ptext (sLit "Non-empty command stack at command:"))
+ 2 (ppr cmd)
+kappaUnderflow :: HsExpr Name -> SDoc
kappaUnderflow cmd
- = hang (ptext SLIT("Command stack underflow at command:"))
- 4 (ppr cmd)
+ = hang (ptext (sLit "Command stack underflow at command:"))
+ 2 (ppr cmd)
+badFormFun :: Int -> TcType -> SDoc
badFormFun i tup_ty'
- = hang (ptext SLIT("The type of the") <+> speakNth i <+> ptext SLIT("argument of a command form has the wrong shape"))
- 4 (ptext SLIT("Argument type:") <+> ppr tup_ty')
+ = hang (ptext (sLit "The type of the") <+> speakNth i <+> ptext (sLit "argument of a command form has the wrong shape"))
+ 2 (ptext (sLit "Argument type:") <+> ppr tup_ty')
\end{code}
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