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 TcMType
import TcBinds
import TcSimplify
-import TcGadt
import TcPat
import TcUnify
import TcRnMonad
+import Coercion
import Inst
import Name
import TysWiredIn
import SrcLoc
import Outputable
import Util
+
+import Control.Monad
\end{code}
%************************************************************************
\begin{code}
tcProc :: InPat Name -> LHsCmdTop Name -- proc pat -> expr
-> BoxyRhoType -- Expected type of whole proc expression
- -> TcM (OutPat TcId, LHsCmdTop TcId)
+ -> TcM (OutPat TcId, LHsCmdTop TcId, CoercionI)
tcProc pat cmd exp_ty
= newArrowScope $
- do { (exp_ty1, res_ty) <- boxySplitAppTy exp_ty
- ; (arr_ty, arg_ty) <- boxySplitAppTy exp_ty1
+ do { ((exp_ty1, res_ty), coi) <- boxySplitAppTy exp_ty
+ ; ((arr_ty, arg_ty), coi1) <- boxySplitAppTy exp_ty1
; let cmd_env = CmdEnv { cmd_arr = arr_ty }
- ; (pat', cmd') <- tcLamPat pat arg_ty (emptyRefinement, res_ty) $
+ ; (pat', cmd') <- tcProcPat pat arg_ty res_ty $
tcCmdTop cmd_env cmd []
- ; return (pat', cmd') }
+ ; let res_coi = mkTransCoI coi (mkAppTyCoI exp_ty1 coi1 res_ty IdCo)
+ ; 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' <- tcGuardedCmd 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)
+ -> 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) }
+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
; 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')
+ = addErrCtxt (cmdCtxt in_cmd) $ do
+ (scrut', scrut_ty) <- addErrCtxt (caseScrutCtxt scrut) $
+ 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 }
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)
where
n_pats = length pats
stk' = drop n_pats cmd_stk
- match_ctxt = LambdaExpr -- Maybe KappaExpr?
+ match_ctxt = (LambdaExpr :: HsMatchContext Name) -- Maybe KappaExpr?
pg_ctxt = PatGuard match_ctxt
tc_grhss (GRHSs grhss binds) res_ty
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 (emptyRefinement, res_ty) $
+ ; (stmts', body') <- tcStmts do_or_lc tc_stmt stmts res_ty $
tcGuardedCmd env body []
; return (HsDo do_or_lc stmts' body' res_ty) }
where
= addErrCtxt (cmdCtxt cmd) $
do { cmds_w_tys <- zipWithM new_cmd_ty cmd_args [1..]
; span <- getSrcSpanM
- ; [w_tv] <- tcInstSkolTyVars (ArrowSkol span) [alphaTyVar]
+ ; [w_tv] <- tcInstSkolTyVars ArrowSkol [alphaTyVar]
; let w_ty = mkTyVarTy w_tv -- Just a convenient starting point
-- a ((w,t1) .. tn) t
-- Check expr
; (expr', lie) <- escapeArrowScope (getLIE (tcMonoExpr expr e_ty))
- ; inst_binds <- tcSimplifyCheck sig_msg [w_tv] [] lie
+ ; 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)
-- the s1..sm and check each cmd
; cmds' <- mapM (tc_cmd w_tv) cmds_w_tys
- ; returnM (HsArrForm (noLoc $ HsWrap (WpTyLam w_tv)
+ ; return (HsArrForm (noLoc $ HsWrap (WpTyLam w_tv)
(unLoc $ mkHsDictLet inst_binds expr'))
fixity cmds')
}
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])
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