Typecheck arrow notation
\begin{code}
-{-# OPTIONS -fno-warn-tabs #-}
--- The above warning supression flag is a temporary kludge.
--- While working on this module you are encouraged to remove it and
--- detab the module (please do the detabbing in a separate patch). See
--- http://ghc.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#TabsvsSpaces
--- for details
+{-# LANGUAGE RankNTypes #-}
module TcArrows ( tcProc ) where
-import {-# SOURCE #-} TcExpr( tcMonoExpr, tcInferRho, tcSyntaxOp, tcCheckId, tcPolyExpr )
+import {-# SOURCE #-} TcExpr( tcMonoExpr, tcInferRho, tcSyntaxOp, tcCheckId, tcPolyExpr )
import HsSyn
import TcMatches
%************************************************************************
-%* *
- Proc
-%* *
+%* *
+ Proc
+%* *
%************************************************************************
\begin{code}
-tcProc :: InPat Name -> LHsCmdTop Name -- proc pat -> expr
- -> TcRhoType -- Expected type of whole proc expression
+tcProc :: InPat Name -> LHsCmdTop Name -- proc pat -> expr
+ -> TcRhoType -- Expected type of whole proc expression
-> TcM (OutPat TcId, LHsCmdTop TcId, TcCoercion)
tcProc pat cmd exp_ty
= newArrowScope $
- do { (co, (exp_ty1, res_ty)) <- matchExpectedAppTy exp_ty
- ; (co1, (arr_ty, arg_ty)) <- matchExpectedAppTy exp_ty1
- ; let cmd_env = CmdEnv { cmd_arr = arr_ty }
+ do { (co, (exp_ty1, res_ty)) <- matchExpectedAppTy exp_ty
+ ; (co1, (arr_ty, arg_ty)) <- matchExpectedAppTy exp_ty1
+ ; let cmd_env = CmdEnv { cmd_arr = arr_ty }
; (pat', cmd') <- tcPat ProcExpr pat arg_ty $
- tcCmdTop cmd_env cmd (unitTy, res_ty)
+ tcCmdTop cmd_env cmd (unitTy, res_ty)
; let res_co = mkTcTransCo co (mkTcAppCo co1 (mkTcNomReflCo res_ty))
; return (pat', cmd', res_co) }
\end{code}
%************************************************************************
-%* *
- Commands
-%* *
+%* *
+ Commands
+%* *
%************************************************************************
\begin{code}
data CmdEnv
= CmdEnv {
- cmd_arr :: TcType -- arrow type constructor, of kind *->*->*
+ cmd_arr :: TcType -- arrow type constructor, of kind *->*->*
}
mkCmdArrTy :: CmdEnv -> TcTauType -> TcTauType -> TcTauType
tcCmdTop env (L loc (HsCmdTop cmd _ _ names)) cmd_ty@(cmd_stk, res_ty)
= setSrcSpan loc $
- do { cmd' <- tcCmd env cmd cmd_ty
- ; names' <- mapM (tcSyntaxName ProcOrigin (cmd_arr env)) names
- ; return (L loc $ HsCmdTop cmd' cmd_stk res_ty names') }
+ do { cmd' <- tcCmd env cmd cmd_ty
+ ; names' <- mapM (tcSyntaxName ProcOrigin (cmd_arr env)) names
+ ; return (L loc $ HsCmdTop cmd' cmd_stk res_ty names') }
----------------------------------------
tcCmd :: CmdEnv -> LHsCmd Name -> CmdType -> TcM (LHsCmd TcId)
- -- The main recursive function
+ -- The main recursive function
tcCmd env (L loc cmd) res_ty
= setSrcSpan loc $ do
- { cmd' <- tc_cmd env cmd res_ty
- ; return (L loc cmd') }
+ { cmd' <- tc_cmd env cmd res_ty
+ ; return (L loc cmd') }
tc_cmd :: CmdEnv -> HsCmd Name -> CmdType -> TcM (HsCmd TcId)
tc_cmd env (HsCmdPar cmd) res_ty
- = do { cmd' <- tcCmd env cmd res_ty
- ; return (HsCmdPar cmd') }
+ = do { cmd' <- tcCmd env cmd res_ty
+ ; return (HsCmdPar cmd') }
tc_cmd env (HsCmdLet binds (L body_loc body)) res_ty
- = do { (binds', body') <- tcLocalBinds binds $
- setSrcSpan body_loc $
- tc_cmd env body res_ty
- ; return (HsCmdLet binds' (L body_loc body')) }
+ = do { (binds', body') <- tcLocalBinds binds $
+ setSrcSpan body_loc $
+ tc_cmd env body res_ty
+ ; return (HsCmdLet binds' (L body_loc body')) }
tc_cmd env in_cmd@(HsCmdCase scrut matches) (stk, res_ty)
= addErrCtxt (cmdCtxt in_cmd) $ do
}
tc_cmd env (HsCmdIf (Just fun) pred b1 b2) res_ty -- Rebindable syntax for if
- = do { pred_ty <- newFlexiTyVarTy openTypeKind
+ = do { pred_ty <- newFlexiTyVarTy openTypeKind
-- For arrows, need ifThenElse :: forall r. T -> r -> r -> r
-- because we're going to apply it to the environment, not
-- the return value.
; (_, [r_tv]) <- tcInstSkolTyVars [alphaTyVar]
- ; let r_ty = mkTyVarTy r_tv
+ ; let r_ty = mkTyVarTy r_tv
; let if_ty = mkFunTys [pred_ty, r_ty, r_ty] r_ty
; checkTc (not (r_tv `elemVarSet` tyVarsOfType pred_ty))
(ptext (sLit "Predicate type of `ifThenElse' depends on result type"))
- ; fun' <- tcSyntaxOp IfOrigin fun if_ty
- ; pred' <- tcMonoExpr pred pred_ty
- ; b1' <- tcCmd env b1 res_ty
- ; b2' <- tcCmd env b2 res_ty
+ ; fun' <- tcSyntaxOp IfOrigin fun if_ty
+ ; pred' <- tcMonoExpr pred pred_ty
+ ; b1' <- tcCmd env b1 res_ty
+ ; b2' <- tcCmd env b2 res_ty
; return (HsCmdIf (Just fun') pred' b1' b2')
}
-------------------------------------------
--- Arrow application
--- (f -< a) or (f -<< a)
+-- Arrow application
+-- (f -< a) or (f -<< a)
--
-- D |- fun :: a t1 t2
-- D,G |- arg :: t1
-- (plus -<< requires ArrowApply)
tc_cmd env cmd@(HsCmdArrApp fun arg _ ho_app lr) (_, res_ty)
- = addErrCtxt (cmdCtxt cmd) $
+ = addErrCtxt (cmdCtxt cmd) $
do { arg_ty <- newFlexiTyVarTy openTypeKind
- ; let fun_ty = mkCmdArrTy env arg_ty res_ty
- ; fun' <- select_arrow_scope (tcMonoExpr fun fun_ty)
+ ; let fun_ty = mkCmdArrTy env arg_ty res_ty
+ ; fun' <- select_arrow_scope (tcMonoExpr fun fun_ty)
-- ToDo: There should be no need for the escapeArrowScope stuff
-- See Note [Escaping the arrow scope] in TcRnTypes
- ; arg' <- tcMonoExpr arg arg_ty
+ ; arg' <- tcMonoExpr arg arg_ty
- ; return (HsCmdArrApp fun' arg' fun_ty ho_app lr) }
+ ; return (HsCmdArrApp fun' arg' fun_ty ho_app lr) }
where
-- Before type-checking f, use the environment of the enclosing
-- proc for the (-<) case.
HsFirstOrderApp -> escapeArrowScope tc
-------------------------------------------
--- Command application
+-- Command application
--
-- D,G |- exp : t
-- D;G |-a cmd : (t,stk) --> res
-- D;G |-a cmd exp : stk --> res
tc_cmd env cmd@(HsCmdApp fun arg) (cmd_stk, res_ty)
- = addErrCtxt (cmdCtxt cmd) $
+ = addErrCtxt (cmdCtxt cmd) $
do { arg_ty <- newFlexiTyVarTy openTypeKind
- ; fun' <- tcCmd env fun (mkPairTy arg_ty cmd_stk, res_ty)
- ; arg' <- tcMonoExpr arg arg_ty
- ; return (HsCmdApp fun' arg') }
+ ; fun' <- tcCmd env fun (mkPairTy arg_ty cmd_stk, res_ty)
+ ; arg' <- tcMonoExpr arg arg_ty
+ ; return (HsCmdApp fun' arg') }
-------------------------------------------
--- Lambda
+-- Lambda
--
-- D;G,x:t |-a cmd : stk --> res
-- ------------------------------
tc_cmd env
(HsCmdLam (MG { mg_alts = [L mtch_loc (match@(Match pats _maybe_rhs_sig grhss))], mg_origin = origin }))
(cmd_stk, res_ty)
- = addErrCtxt (pprMatchInCtxt match_ctxt match) $
- do { (co, arg_tys, cmd_stk') <- matchExpectedCmdArgs n_pats cmd_stk
+ = addErrCtxt (pprMatchInCtxt match_ctxt match) $
+ do { (co, arg_tys, cmd_stk') <- matchExpectedCmdArgs n_pats cmd_stk
- -- Check the patterns, and the GRHSs inside
- ; (pats', grhss') <- setSrcSpan mtch_loc $
+ -- Check the patterns, and the GRHSs inside
+ ; (pats', grhss') <- setSrcSpan mtch_loc $
tcPats LambdaExpr pats arg_tys $
tc_grhss grhss cmd_stk' res_ty
- ; let match' = L mtch_loc (Match pats' Nothing grhss')
+ ; let match' = L mtch_loc (Match pats' Nothing grhss')
arg_tys = map hsLPatType pats'
cmd' = HsCmdLam (MG { mg_alts = [match'], mg_arg_tys = arg_tys
, mg_res_ty = res_ty, mg_origin = origin })
- ; return (mkHsCmdCast co cmd') }
+ ; return (mkHsCmdCast co cmd') }
where
n_pats = length pats
- match_ctxt = (LambdaExpr :: HsMatchContext Name) -- Maybe KappaExpr?
+ match_ctxt = (LambdaExpr :: HsMatchContext Name) -- Maybe KappaExpr?
pg_ctxt = PatGuard match_ctxt
tc_grhss (GRHSs grhss binds) stk_ty res_ty
- = do { (binds', grhss') <- tcLocalBinds binds $
- mapM (wrapLocM (tc_grhs stk_ty res_ty)) grhss
- ; return (GRHSs grhss' binds') }
+ = do { (binds', grhss') <- tcLocalBinds binds $
+ mapM (wrapLocM (tc_grhs stk_ty res_ty)) grhss
+ ; return (GRHSs grhss' binds') }
tc_grhs stk_ty res_ty (GRHS guards body)
- = do { (guards', rhs') <- tcStmtsAndThen pg_ctxt tcGuardStmt guards res_ty $
- \ res_ty -> tcCmd env body (stk_ty, res_ty)
- ; return (GRHS guards' rhs') }
+ = do { (guards', rhs') <- tcStmtsAndThen pg_ctxt tcGuardStmt guards res_ty $
+ \ res_ty -> tcCmd env body (stk_ty, res_ty)
+ ; return (GRHS guards' rhs') }
-------------------------------------------
--- Do notation
+-- Do notation
tc_cmd env (HsCmdDo stmts _) (cmd_stk, res_ty)
- = do { co <- unifyType unitTy cmd_stk -- Expecting empty argument stack
- ; stmts' <- tcStmts ArrowExpr (tcArrDoStmt env) stmts res_ty
- ; return (mkHsCmdCast co (HsCmdDo stmts' res_ty)) }
+ = do { co <- unifyType unitTy cmd_stk -- Expecting empty argument stack
+ ; stmts' <- tcStmts ArrowExpr (tcArrDoStmt env) stmts res_ty
+ ; return (mkHsCmdCast co (HsCmdDo stmts' res_ty)) }
-----------------------------------------------------------------
--- Arrow ``forms'' (| e c1 .. cn |)
+-- Arrow ``forms'' (| e c1 .. cn |)
--
--- D; G |-a1 c1 : stk1 --> r1
--- ...
--- D; G |-an cn : stkn --> rn
--- D |- e :: forall e. a1 (e, stk1) t1
+-- D; G |-a1 c1 : stk1 --> r1
+-- ...
+-- D; G |-an cn : stkn --> rn
+-- D |- e :: forall e. a1 (e, stk1) t1
-- ...
-- -> an (e, stkn) tn
-- -> a (e, stk) t
--- e \not\in (stk, stk1, ..., stkm, t, t1, ..., tn)
--- ----------------------------------------------
--- D; G |-a (| e c1 ... cn |) : stk --> t
+-- e \not\in (stk, stk1, ..., stkm, t, t1, ..., tn)
+-- ----------------------------------------------
+-- D; G |-a (| e c1 ... cn |) : stk --> t
-tc_cmd env cmd@(HsCmdArrForm expr fixity cmd_args) (cmd_stk, res_ty)
- = addErrCtxt (cmdCtxt cmd) $
- do { (cmd_args', cmd_tys) <- mapAndUnzipM tc_cmd_arg cmd_args
+tc_cmd env cmd@(HsCmdArrForm expr fixity cmd_args) (cmd_stk, res_ty)
+ = addErrCtxt (cmdCtxt cmd) $
+ do { (cmd_args', cmd_tys) <- mapAndUnzipM tc_cmd_arg cmd_args
; let e_ty = mkForAllTy alphaTyVar $ -- We use alphaTyVar for 'w'
mkFunTys cmd_tys $
mkCmdArrTy env (mkPairTy alphaTy cmd_stk) res_ty
tc_cmd_arg :: LHsCmdTop Name -> TcM (LHsCmdTop TcId, TcType)
tc_cmd_arg cmd
= do { arr_ty <- newFlexiTyVarTy arrowTyConKind
- ; stk_ty <- newFlexiTyVarTy liftedTypeKind
- ; res_ty <- newFlexiTyVarTy liftedTypeKind
- ; let env' = env { cmd_arr = arr_ty }
- ; cmd' <- tcCmdTop env' cmd (stk_ty, res_ty)
- ; return (cmd', mkCmdArrTy env' (mkPairTy alphaTy stk_ty) res_ty) }
+ ; stk_ty <- newFlexiTyVarTy liftedTypeKind
+ ; res_ty <- newFlexiTyVarTy liftedTypeKind
+ ; let env' = env { cmd_arr = arr_ty }
+ ; cmd' <- tcCmdTop env' cmd (stk_ty, res_ty)
+ ; return (cmd', mkCmdArrTy env' (mkPairTy alphaTy stk_ty) res_ty) }
-----------------------------------------------------------------
--- Base case for illegal commands
+-- Base case for illegal commands
-- This is where expressions that aren't commands get rejected
tc_cmd _ cmd _
= failWithTc (vcat [ptext (sLit "The expression"), nest 2 (ppr cmd),
- ptext (sLit "was found where an arrow command was expected")])
+ ptext (sLit "was found where an arrow command was expected")])
matchExpectedCmdArgs :: Arity -> TcType -> TcM (TcCoercion, [TcType], TcType)
%************************************************************************
-%* *
- Stmts
-%* *
+%* *
+ Stmts
+%* *
%************************************************************************
\begin{code}
--------------------------------
--- Mdo-notation
+-- Mdo-notation
-- The distinctive features here are
--- (a) RecStmts, and
--- (b) no rebindable syntax
+-- (a) RecStmts, and
+-- (b) no rebindable syntax
tcArrDoStmt :: CmdEnv -> TcCmdStmtChecker
tcArrDoStmt env _ (LastStmt rhs _) res_ty thing_inside
- = do { rhs' <- tcCmd env rhs (unitTy, res_ty)
- ; thing <- thing_inside (panic "tcArrDoStmt")
- ; return (LastStmt rhs' noSyntaxExpr, thing) }
+ = do { rhs' <- tcCmd env rhs (unitTy, res_ty)
+ ; thing <- thing_inside (panic "tcArrDoStmt")
+ ; return (LastStmt rhs' noSyntaxExpr, thing) }
tcArrDoStmt env _ (BodyStmt rhs _ _ _) res_ty thing_inside
- = do { (rhs', elt_ty) <- tc_arr_rhs env rhs
- ; thing <- thing_inside res_ty
- ; return (BodyStmt rhs' noSyntaxExpr noSyntaxExpr elt_ty, thing) }
+ = do { (rhs', elt_ty) <- tc_arr_rhs env rhs
+ ; thing <- thing_inside res_ty
+ ; return (BodyStmt 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 $
+ = 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) }
+ ; return (BindStmt pat' rhs' noSyntaxExpr noSyntaxExpr, thing) }
tcArrDoStmt env ctxt (RecStmt { recS_stmts = stmts, recS_later_ids = later_names
, recS_rec_ids = rec_names }) res_ty thing_inside
; let tup_ids = zipWith mkLocalId tup_names tup_elt_tys
; tcExtendIdEnv tup_ids $ do
{ (stmts', tup_rets)
- <- tcStmtsAndThen ctxt (tcArrDoStmt env) stmts res_ty $ \ _res_ty' ->
- -- ToDo: res_ty not really right
+ <- tcStmtsAndThen ctxt (tcArrDoStmt env) stmts res_ty $ \ _res_ty' ->
+ -- ToDo: res_ty not really right
zipWithM tcCheckId tup_names tup_elt_tys
; thing <- 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)
+ -- 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)
; let rec_ids = takeList rec_names tup_ids
; later_ids <- tcLookupLocalIds later_names
, recS_later_rets = later_rets
, 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 -> LHsCmd Name -> TcM (LHsCmd TcId, TcType)
tc_arr_rhs env rhs = do { ty <- newFlexiTyVarTy liftedTypeKind
- ; rhs' <- tcCmd env rhs (unitTy, ty)
- ; return (rhs', ty) }
+ ; rhs' <- tcCmd env rhs (unitTy, ty)
+ ; return (rhs', ty) }
\end{code}
%************************************************************************
-%* *
- Helpers
-%* *
+%* *
+ Helpers
+%* *
%************************************************************************
mkPairTy :: Type -> Type -> Type
mkPairTy t1 t2 = mkTyConApp pairTyCon [t1,t2]
-arrowTyConKind :: Kind -- *->*->*
+arrowTyConKind :: Kind -- *->*->*
arrowTyConKind = mkArrowKinds [liftedTypeKind, liftedTypeKind] liftedTypeKind
\end{code}
%************************************************************************
-%* *
- Errors
-%* *
+%* *
+ Errors
+%* *
%************************************************************************
\begin{code}
git.haskell.org / ghc.git / blobdiff