-%
+2%
% (c) The GRASP/AQUA Project, Glasgow University, 1992-1998
%
\section[TcSplice]{Template Haskell splices}
import TcExpr ( tcMonoExpr )
import TcHsSyn ( TcExpr, TypecheckedHsExpr, mkHsLet, zonkTopExpr )
import TcSimplify ( tcSimplifyTop )
-import TcType ( TcType, openTypeKind )
+import TcType ( TcType, openTypeKind, mkAppTy )
import TcEnv ( spliceOK, tcMetaTy )
import TcRnTypes ( TopEnv(..) )
-import TcMType ( newTyVarTy )
+import TcMType ( newTyVarTy, zapToType )
import Name ( Name )
import TcRnMonad
import TysWiredIn ( mkListTy )
-import DsMeta ( exprTyConName, declTyConName )
+import DsMeta ( exprTyConName, declTyConName, decTyConName, qTyConName )
+import ErrUtils (Message)
import Outputable
+import Panic ( showException )
import GHC.Base ( unsafeCoerce# ) -- Should have a better home in the module hierarchy
+import Monad (liftM)
\end{code}
= newTyVarTy openTypeKind `thenM` \ any_ty ->
tcMonoExpr expr any_ty `thenM_`
tcMetaTy exprTyConName
+ -- Result type is Expr (= Q Exp)
tcBracket (DecBr decls)
= tcTopSrcDecls decls `thenM_`
- tcMetaTy declTyConName `thenM` \ decl_ty ->
- returnM (mkListTy decl_ty)
+ tcMetaTy decTyConName `thenM` \ decl_ty ->
+ tcMetaTy qTyConName `thenM` \ q_ty ->
+ returnM (mkAppTy q_ty (mkListTy decl_ty))
+ -- Result type is Q [Dec]
\end{code}
+
%************************************************************************
%* *
\subsection{Splicing an expression}
Brack _ ps_var lie_var ->
-- A splice inside brackets
- -- NB: ignore res_ty
+ -- NB: ignore res_ty, apart from zapping it to a mono-type
-- e.g. [| reverse $(h 4) |]
-- Here (h 4) :: Q Exp
-- but $(h 4) :: forall a.a i.e. anything!
+ zapToType res_ty `thenM_`
tcMetaTy exprTyConName `thenM` \ meta_exp_ty ->
setStage (Splice next_level) (
setLIEVar lie_var $
-- inner escape before dealing with the outer one
tcTopSplice expr res_ty
- = tcMetaTy exprTyConName `thenM` \ meta_exp_ty ->
- setStage topSpliceStage (
- getLIE (tcMonoExpr expr meta_exp_ty)
- ) `thenM` \ (expr', lie) ->
+ = checkNoErrs (
+ -- checkNoErrs: must not try to run the thing
+ -- if the type checker fails!
+
+ tcMetaTy exprTyConName `thenM` \ meta_exp_ty ->
+ setStage topSpliceStage (
+ getLIE (tcMonoExpr expr meta_exp_ty)
+ ) `thenM` \ (expr', lie) ->
-- Solve the constraints
- tcSimplifyTop lie `thenM` \ const_binds ->
- let
- q_expr = mkHsLet const_binds expr'
- in
- zonkTopExpr q_expr `thenM` \ zonked_q_expr ->
+ tcSimplifyTop lie `thenM` \ const_binds ->
+
+ -- Wrap the bindings around it and zonk
+ zonkTopExpr (mkHsLet const_binds expr')
+ ) `thenM` \ zonked_q_expr ->
-- Run the expression
traceTc (text "About to run" <+> ppr zonked_q_expr) `thenM_`
expr2 = convertToHsExpr simple_expr
in
traceTc (text "Got result" <+> ppr expr2) `thenM_`
+
+ showSplice "expression"
+ zonked_q_expr (ppr expr2) `thenM_`
initRn SourceMode (rnExpr expr2) `thenM` \ (exp3, fvs) ->
importSupportingDecls fvs `thenM` \ env ->
\begin{code}
-- Always at top level
tcSpliceDecls expr
- = tcMetaTy declTyConName `thenM` \ meta_dec_ty ->
+ = tcMetaTy decTyConName `thenM` \ meta_dec_ty ->
+ tcMetaTy qTyConName `thenM` \ meta_q_ty ->
setStage topSpliceStage (
- getLIE (tcMonoExpr expr (mkListTy meta_dec_ty))
+ getLIE (tcMonoExpr expr (mkAppTy meta_q_ty (mkListTy meta_dec_ty)))
) `thenM` \ (expr', lie) ->
-- Solve the constraints
tcSimplifyTop lie `thenM` \ const_binds ->
-- Run the expression
traceTc (text "About to run" <+> ppr zonked_q_expr) `thenM_`
runMetaD zonked_q_expr `thenM` \ simple_expr ->
- let
- -- simple_expr :: [Meta.Dec]
- decls :: [RdrNameHsDecl]
- decls = convertToHsDecls simple_expr
- in
+ -- simple_expr :: [Meta.Dec]
+ -- decls :: [RdrNameHsDecl]
+ handleErrors (convertToHsDecls simple_expr) `thenM` \ decls ->
traceTc (text "Got result" <+> vcat (map ppr decls)) `thenM_`
+ showSplice "declarations"
+ zonked_q_expr (vcat (map ppr decls)) `thenM_`
returnM decls
+
+ where handleErrors :: [Either a Message] -> TcM [a]
+ handleErrors [] = return []
+ handleErrors (Left x:xs) = liftM (x:) (handleErrors xs)
+ handleErrors (Right m:xs) = do addErrTc m
+ handleErrors xs
\end{code}
\begin{code}
runMetaE :: TypecheckedHsExpr -- Of type (Q Exp)
-> TcM Meta.Exp -- Of type Exp
-runMetaE e = runMeta tcRunQ e
+runMetaE e = runMeta e
-runMetaD :: TypecheckedHsExpr -- Of type [Q Dec]
+runMetaD :: TypecheckedHsExpr -- Of type Q [Dec]
-> TcM [Meta.Dec] -- Of type [Dec]
-runMetaD e = runMeta run_decl e
- where
- run_decl :: [Meta.Decl] -> TcM [Meta.Dec]
- run_decl ds = mappM tcRunQ ds
+runMetaD e = runMeta e
--- Warning: if Q is anything other than IO, we need to change this
-tcRunQ :: Meta.Q a -> TcM a
-tcRunQ thing = ioToTcRn thing
-
-
-runMeta :: (x -> TcM t) -- :: X -> IO t
- -> TypecheckedHsExpr -- Of type X
+runMeta :: TypecheckedHsExpr -- Of type X
-> TcM t -- Of type t
-runMeta run_it expr :: TcM t
+runMeta expr
= getTopEnv `thenM` \ top_env ->
+ getGblEnv `thenM` \ tcg_env ->
getEps `thenM` \ eps ->
getNameCache `thenM` \ name_cache ->
getModule `thenM` \ this_mod ->
- getGlobalRdrEnv `thenM` \ rdr_env ->
let
ghci_mode = top_mode top_env
pcs = PCS { pcs_nc = name_cache, pcs_EPS = eps }
- print_unqual = unQualInScope rdr_env
+ type_env = tcg_type_env tcg_env
+ rdr_env = tcg_rdr_env tcg_env
in
- if (ghci_mode == OneShot) then
- failWithTc (ptext SLIT("You must use --make or --interactive to run splice expressions"))
- -- The reason for this is that the demand-linker doesn't have
- -- enough information available to link all the things that
- -- are needed when you try to run a splice
- else
-
- ioToTcRn (HscMain.compileExpr hsc_env pcs this_mod
- print_unqual expr) `thenM` \ hval ->
-
- tryM (run_it (unsafeCoerce# hval)) `thenM` \ either_tval ->
+ -- Wrap the compile-and-run in an exception-catcher
+ -- Compiling might fail if linking fails
+ -- Running might fail if it throws an exception
+ tryM (ioToTcRn (do
+ hval <- HscMain.compileExpr
+ hsc_env pcs this_mod
+ rdr_env type_env expr
+ Meta.runQ (unsafeCoerce# hval) -- Coerce it to Q t, and run it
+ )) `thenM` \ either_tval ->
case either_tval of
- Left exn -> failWithTc (vcat [text "Exception when running compile-time code:",
+ Left exn -> failWithTc (vcat [text "Exception when trying to run compile-time code:",
nest 4 (vcat [text "Code:" <+> ppr expr,
- text ("Exn: " ++ show exn)])])
+ text ("Exn: " ++ Panic.showException exn)])])
Right v -> returnM v
\end{code}
%************************************************************************
\begin{code}
+showSplice :: String -> TypecheckedHsExpr -> SDoc -> TcM ()
+showSplice what before after
+ = getSrcLocM `thenM` \ loc ->
+ traceSplice (vcat [ppr loc <> colon <+> text "Splicing" <+> text what,
+ nest 2 (sep [nest 2 (ppr before),
+ text "======>",
+ nest 2 after])])
+
illegalSplice level
= ptext SLIT("Illegal splice at level") <+> ppr level
projects / ghc-hetmet.git / blobdiff