\begin{code}
module TcArrows ( tcProc ) where
-import {-# SOURCE #-} TcExpr( tcMonoExpr, tcInferRho, tcSyntaxOp )
+import {-# SOURCE #-} TcExpr( tcMonoExpr, tcInferRho, tcSyntaxOp, tcCheckId )
import HsSyn
import TcMatches
import TcPat
import TcUnify
import TcRnMonad
+import TcEnv
import Coercion
+import Id( mkLocalId )
import Inst
import Name
import TysWiredIn
\begin{code}
tcProc :: InPat Name -> LHsCmdTop Name -- proc pat -> expr
-> TcRhoType -- Expected type of whole proc expression
- -> TcM (OutPat TcId, LHsCmdTop TcId, CoercionI)
+ -> TcM (OutPat TcId, LHsCmdTop TcId, Coercion)
tcProc pat cmd exp_ty
= newArrowScope $
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') <- tcPat ProcExpr pat arg_ty $
+ ; (pat', cmd') <- tcPat ProcExpr pat arg_ty $
tcCmdTop cmd_env cmd [] res_ty
- ; let res_coi = mkTransCoI coi (mkAppTyCoI coi1 (IdCo res_ty))
- ; return (pat', cmd', res_coi) }
+ ; let res_coi = mkTransCo coi (mkAppCo coi1 (mkReflCo res_ty))
+ ; return (pat', cmd', res_coi) }
\end{code}
tcCmdTop env (L loc (HsCmdTop cmd _ _ names)) cmd_stk res_ty
= setSrcSpan loc $
- do { cmd' <- tcGuardedCmd env cmd cmd_stk 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
- -> TcTauType -> TcM (LHsExpr TcId)
--- A wrapper that deals with the refinement (if any)
-tcGuardedCmd env expr stk res_ty
- = do { body <- tcCmd env expr (stk, res_ty)
- ; return body
- }
-
tcCmd :: CmdEnv -> LHsExpr Name -> (CmdStack, TcTauType) -> TcM (LHsExpr TcId)
-- The main recursive function
tcCmd env (L loc expr) res_ty
where
match_ctxt = MC { mc_what = CaseAlt,
mc_body = mc_body }
- mc_body body res_ty' = tcGuardedCmd env body stk res_ty'
+ 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
-- Check the patterns, and the GRHSs inside
; (pats', grhss') <- setSrcSpan mtch_loc $
- tcPats LambdaExpr pats cmd_stk $
- tc_grhss grhss res_ty
+ 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 (tcMDoStmt tc_rhs) stmts 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_rhs rhs = do { ty <- newFlexiTyVarTy liftedTypeKind
- ; rhs' <- tcCmd env rhs ([], ty)
- ; return (rhs', ty) }
-----------------------------------------------------------------
e_res_ty
-- Check expr
- ; (inst_binds, expr') <- checkConstraints ArrowSkol [w_tv] [] $
+ ; (inst_binds, expr') <- checkConstraints ArrowSkol [w_tv] [] $
escapeArrowScope (tcMonoExpr expr e_ty)
-- OK, now we are in a position to unscramble
-- 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')
%************************************************************************
%* *
+ 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}
+
+
+%************************************************************************
+%* *
Helpers
%* *
%************************************************************************
projects / ghc-hetmet.git / blobdiff