+++ /dev/null
-%
-% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
-%
-\section{Typecheck arrow notation}
-
-\begin{code}
-module TcArrows ( tcProc ) where
-
-#include "HsVersions.h"
-
-import {-# SOURCE #-} TcExpr( tcMonoExpr, tcInferRho )
-
-import HsSyn
-import TcHsSyn ( mkHsDictLet )
-
-import TcMatches ( matchCtxt, tcStmts, tcMDoStmt, tcGuardStmt,
- TcMatchCtxt(..), tcMatchesCase )
-
-import TcType ( TcType, TcTauType, BoxyRhoType, mkFunTys, mkTyConApp,
- mkTyVarTy, mkAppTys, tcSplitTyConApp_maybe, tcEqType,
- SkolemInfo(..) )
-import TcMType ( newFlexiTyVarTy, tcInstSkolTyVars, zonkTcType )
-import TcBinds ( tcLocalBinds )
-import TcSimplify ( tcSimplifyCheck )
-import TcPat ( tcPat, tcPats, PatCtxt(..) )
-import TcUnify ( checkSigTyVarsWrt, boxySplitAppTy )
-import TcRnMonad
-import Inst ( tcSyntaxName )
-import Name ( Name )
-import TysWiredIn ( boolTy, pairTyCon )
-import VarSet
-import TysPrim ( alphaTyVar )
-import Type ( Kind, mkArrowKinds, liftedTypeKind, openTypeKind, tyVarsOfTypes )
-
-import SrcLoc ( Located(..) )
-import Outputable
-import Util ( lengthAtLeast )
-
-\end{code}
-
-%************************************************************************
-%* *
- Proc
-%* *
-%************************************************************************
-
-\begin{code}
-tcProc :: InPat Name -> LHsCmdTop Name -- proc pat -> expr
- -> BoxyRhoType -- Expected type of whole proc expression
- -> TcM (OutPat TcId, LHsCmdTop TcId)
-
-tcProc pat cmd exp_ty
- = newArrowScope $
- do { (exp_ty1, res_ty) <- boxySplitAppTy exp_ty
- ; (arr_ty, arg_ty) <- boxySplitAppTy exp_ty1
- ; let cmd_env = CmdEnv { cmd_arr = arr_ty }
- ; (pat', cmd') <- tcPat LamPat pat arg_ty res_ty $ \ res_ty' ->
- tcCmdTop cmd_env cmd ([], res_ty')
- ; return (pat', cmd') }
-\end{code}
-
-
-%************************************************************************
-%* *
- Commands
-%* *
-%************************************************************************
-
-\begin{code}
-type CmdStack = [TcTauType]
-data CmdEnv
- = CmdEnv {
- cmd_arr :: TcType -- arrow type constructor, of kind *->*->*
- }
-
-mkCmdArrTy :: CmdEnv -> TcTauType -> TcTauType -> TcTauType
-mkCmdArrTy env t1 t2 = mkAppTys (cmd_arr env) [t1, t2]
-
----------------------------------------
-tcCmdTop :: CmdEnv
- -> LHsCmdTop Name
- -> (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, res_ty)
- = setSrcSpan loc $
- 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') }
-
-
-----------------------------------------
-tcCmd :: CmdEnv -> LHsExpr Name -> (CmdStack, TcTauType) -> TcM (LHsExpr TcId)
- -- The main recursive function
-tcCmd env (L loc expr) res_ty
- = setSrcSpan loc $ do
- { expr' <- tc_cmd env expr res_ty
- ; return (L loc expr') }
-
-tc_cmd env (HsPar cmd) res_ty
- = do { cmd' <- tcCmd env cmd res_ty
- ; return (HsPar cmd') }
-
-tc_cmd env (HsLet binds (L body_loc body)) res_ty
- = do { (binds', body') <- tcLocalBinds binds $
- setSrcSpan body_loc $
- tc_cmd env body res_ty
- ; return (HsLet binds' (L body_loc body')) }
-
-tc_cmd env in_cmd@(HsCase scrut matches) (stk, res_ty)
- = addErrCtxt (cmdCtxt in_cmd) $
- addErrCtxt (caseScrutCtxt scrut) (
- tcInferRho scrut
- ) `thenM` \ (scrut', scrut_ty) ->
- tcMatchesCase match_ctxt scrut_ty matches res_ty `thenM` \ matches' ->
- returnM (HsCase scrut' matches')
- where
- match_ctxt = MC { mc_what = CaseAlt,
- mc_body = mc_body }
- mc_body body res_ty' = tcCmd 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')
- }
-
--------------------------------------------
--- Arrow application
--- (f -< a) or (f -<< a)
-
-tc_cmd env cmd@(HsArrApp fun arg _ ho_app lr) (cmd_stk, res_ty)
- = addErrCtxt (cmdCtxt cmd) $
- do { arg_ty <- newFlexiTyVarTy openTypeKind
- ; let fun_ty = mkCmdArrTy env (foldl mkPairTy arg_ty cmd_stk) res_ty
-
- ; fun' <- select_arrow_scope (tcMonoExpr fun fun_ty)
-
- ; arg' <- tcMonoExpr arg arg_ty
-
- ; return (HsArrApp fun' arg' fun_ty ho_app lr) }
- where
- -- Before type-checking f, use the environment of the enclosing
- -- proc for the (-<) case.
- -- Local bindings, inside the enclosing proc, are not in scope
- -- inside f. In the higher-order case (-<<), they are.
- select_arrow_scope tc = case ho_app of
- HsHigherOrderApp -> tc
- HsFirstOrderApp -> escapeArrowScope tc
-
--------------------------------------------
--- Command application
-
-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)
-
- ; arg' <- tcMonoExpr arg arg_ty
-
- ; return (HsApp fun' arg') }
-
--------------------------------------------
--- Lambda
-
--- gaw 2004
-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) $
-
- do { -- Check the cmd stack is big enough
- ; checkTc (lengthAtLeast cmd_stk n_pats)
- (kappaUnderflow cmd)
-
- -- Check the patterns, and the GRHSs inside
- ; (pats', grhss') <- setSrcSpan mtch_loc $
- tcPats LamPat pats cmd_stk res_ty $
- tc_grhss grhss
-
- ; let match' = L mtch_loc (Match pats' Nothing grhss')
- ; return (HsLam (MatchGroup [match'] res_ty))
- }
-
- where
- n_pats = length pats
- stk' = drop n_pats cmd_stk
- match_ctxt = LambdaExpr -- Maybe KappaExpr?
- pg_ctxt = PatGuard match_ctxt
-
- tc_grhss (GRHSs grhss binds) res_ty
- = do { (binds', grhss') <- tcLocalBinds binds $
- mapM (wrapLocM (tc_grhs res_ty)) grhss
- ; return (GRHSs grhss' binds') }
-
- tc_grhs res_ty (GRHS guards body)
- = do { (guards', rhs') <- tcStmts 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)
- = do { checkTc (null cmd_stk) (nonEmptyCmdStkErr cmd)
- ; (stmts', body') <- tcStmts do_or_lc tc_stmt stmts res_ty $ \ res_ty' ->
- tcCmd env body ([], res_ty')
- ; return (HsDo do_or_lc stmts' body' res_ty) }
- where
- tc_stmt = tcMDoStmt tc_rhs
- tc_rhs rhs = do { ty <- newFlexiTyVarTy liftedTypeKind
- ; rhs' <- tcCmd env rhs ([], ty)
- ; return (rhs', ty) }
-
-
------------------------------------------------------------------
--- Arrow ``forms'' (| e c1 .. cn |)
---
--- G |-b c : [s1 .. sm] s
--- pop(G) |- e : forall w. b ((w,s1) .. sm) s
--- -> a ((w,t1) .. tn) t
--- e \not\in (s, s1..sm, t, t1..tn)
--- ----------------------------------------------
--- G |-a (| e c |) : [t1 .. tn] t
-
-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 span) [alphaTyVar]
- ; let w_ty = mkTyVarTy w_tv -- Just a convenient starting point
-
- -- a ((w,t1) .. tn) t
- ; let e_res_ty = mkCmdArrTy env (foldl mkPairTy w_ty cmd_stk) res_ty
-
- -- b ((w,s1) .. sm) s
- -- -> a ((w,t1) .. tn) t
- ; let e_ty = mkFunTys [mkAppTys b [tup,s] | (_,_,b,tup,s) <- cmds_w_tys]
- e_res_ty
-
- -- Check expr
- ; (expr', lie) <- escapeArrowScope (getLIE (tcMonoExpr expr e_ty))
- ; inst_binds <- tcSimplifyCheck sig_msg [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]
-
- -- 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
-
- ; returnM (HsArrForm (mkHsTyLam [w_tv] (mkHsDictLet inst_binds expr')) fixity cmds')
- }
- where
- -- Make the types
- -- b, ((e,s1) .. sm), s
- new_cmd_ty :: LHsCmdTop Name -> Int
- -> TcM (LHsCmdTop Name, Int, TcType, TcType, TcType)
- new_cmd_ty cmd i
--- gaw 2004 FIX?
- = do { b_ty <- newFlexiTyVarTy arrowTyConKind
- ; tup_ty <- newFlexiTyVarTy liftedTypeKind
- -- We actually make a type variable for the tuple
- -- because we don't know how deeply nested it is yet
- ; s_ty <- newFlexiTyVarTy liftedTypeKind
- ; return (cmd, i, b_ty, tup_ty, s_ty)
- }
-
- tc_cmd w_tv (cmd, i, b, tup_ty, s)
- = do { tup_ty' <- zonkTcType tup_ty
- ; let (corner_ty, arg_tys) = unscramble tup_ty'
-
- -- Check that it has the right shape:
- -- ((w,s1) .. sn)
- -- where the si do not mention w
- ; checkTc (corner_ty `tcEqType` mkTyVarTy w_tv &&
- not (w_tv `elemVarSet` tyVarsOfTypes arg_tys))
- (badFormFun i tup_ty')
-
- ; tcCmdTop (env { cmd_arr = b }) cmd (arg_tys, s) }
-
- unscramble :: TcType -> (TcType, [TcType])
- -- unscramble ((w,s1) .. sn) = (w, [s1..sn])
- unscramble ty
- = case tcSplitTyConApp_maybe ty of
- Just (tc, [t,s]) | tc == pairTyCon
- -> let
- (w,ss) = unscramble t
- in (w, s:ss)
-
- other -> (ty, [])
-
- sig_msg = ptext SLIT("expected type of a command form")
-
------------------------------------------------------------------
--- 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")])
-\end{code}
-
-
-%************************************************************************
-%* *
- Helpers
-%* *
-%************************************************************************
-
-
-\begin{code}
-mkPairTy t1 t2 = mkTyConApp pairTyCon [t1,t2]
-
-arrowTyConKind :: Kind -- *->*->*
-arrowTyConKind = mkArrowKinds [liftedTypeKind, liftedTypeKind] liftedTypeKind
-\end{code}
-
-
-%************************************************************************
-%* *
- Errors
-%* *
-%************************************************************************
-
-\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)
-
-nonEmptyCmdStkErr cmd
- = hang (ptext SLIT("Non-empty command stack at command:"))
- 4 (ppr cmd)
-
-kappaUnderflow cmd
- = hang (ptext SLIT("Command stack underflow at command:"))
- 4 (ppr cmd)
-
-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')
-\end{code}
projects / ghc-hetmet.git / blobdiff