%
% (c) The University of Glasgow 2006
% (c) The GRASP/AQUA Project, Glasgow University, 19921998
%
TcSplice: Template Haskell splices
\begin{code}
module TcSplice( kcSpliceType, tcSpliceExpr, tcSpliceDecls, tcBracket,
lookupThName_maybe,
runQuasiQuoteExpr, runQuasiQuotePat, runAnnotation ) where
#include "HsVersions.h"
import HscMain
import TcRnDriver
import HsSyn
import Convert
import RnExpr
import RnEnv
import RdrName
import RnTypes
import TcExpr
import TcHsSyn
import TcSimplify
import TcUnify
import TcType
import TcEnv
import TcMType
import TcHsType
import TcIface
import TypeRep
import Name
import NameEnv
import PrelNames
import HscTypes
import OccName
import Var
import Module
import Annotations
import TcRnMonad
import Class
import Inst
import TyCon
import DataCon
import Id
import IdInfo
import TysWiredIn
import DsMeta
import DsExpr
import DsMonad hiding (Splice)
import Serialized
import ErrUtils
import SrcLoc
import Outputable
import Unique
import Data.Maybe
import BasicTypes
import Panic
import FastString
import Exception
import qualified Language.Haskell.TH as TH
import qualified Language.Haskell.TH.Syntax as TH
#ifdef GHCI
import GHC.Desugar ( AnnotationWrapper(..) )
#endif
import GHC.Exts ( unsafeCoerce#, Int#, Int(..) )
import System.IO.Error
\end{code}
Note [How toplevel splices are handled]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Toplevel splices (those not inside a [| .. |] quotation bracket) are handled
very straightforwardly:
1. tcTopSpliceExpr: typecheck the body e of the splice $(e)
2. runMetaT: desugar, compile, run it, and convert result back to
HsSyn RdrName (of the appropriate flavour, eg HsType RdrName,
HsExpr RdrName etc)
3. treat the result as if that's what you saw in the first place
e.g for HsType, rename and kindcheck
for HsExpr, rename and typecheck
(The last step is different for decls, becuase they can *only* be
toplevel: we return the result of step 2.)
Note [How brackets and nested splices are handled]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Nested splices (those inside a [| .. |] quotation bracket), are treated
quite differently.
* After typechecking, the bracket [| |] carries
a) A mutable list of PendingSplice
type PendingSplice = (Name, LHsExpr Id)
b) The quoted expression e, *renamed*: (HsExpr Name)
The expression e has been typechecked, but the result of
that typechecking is discarded.
* The brakcet is desugared by DsMeta.dsBracket. It
a) Extends the ds_meta environment with the PendingSplices
attached to the bracket
b) Converts the quoted (HsExpr Name) to a CoreExpr that, when
run, will produce a suitable TH expression/type/decl. This
is why we leave the *renamed* expression attached to the bracket:
the quoted expression should not be decorated with all the goop
added by the type checker
* Each splice carries a unique Name, called a "splice point", thus
${n}(e). The name is initialised to an (Unqual "splice") when the
splice is created; the renamer gives it a unique.
* When the type checker typechecks a nested splice ${n}(e), it
typechecks e
adds the typechecked expression (of type (HsExpr Id))
as a pending splice to the enclosing bracket
returns something noncommittal
Eg for [| f ${n}(g x) |], the typechecker
attaches the typechecked term (g x) to the pending splices for n
in the outer bracket
returns a noncommittal type \alpha.
Remember that the bracket discards the typechecked term altogether
* When DsMeta (used to desugar the body of the bracket) comes across
a splice, it looks up the splice's Name, n, in the ds_meta envt,
to find an (HsExpr Id) that should be substituted for the splice;
it just desugars it to get a CoreExpr (DsMeta.repSplice).
Example:
Source: f = [| Just $(g 3) |]
The [| |] part is a HsBracket
Typechecked: f = [| Just ${s7}(g 3) |]{s7 = g Int 3}
The [| |] part is a HsBracketOut, containing *renamed*
(not typechecked) expression
The "s7" is the "splice point"; the (g Int 3) part
is a typechecked expression
Desugared: f = do { s7 <- g Int 3
; return (ConE "Data.Maybe.Just" s7) }
Note [Template Haskell state diagram]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Here are the ThStages, s, their corresponding level numbers
(the result of (thLevel s)), and their state transitions.
| Comp | ---------> | Splice | -----|
| 1 | | 0 | <----|
^ | ^ |
$ | | [||] $ | | [||]
| v | v
| Brack Comp | | Brack Splice |
| 2 | | 1 |
* Normal toplevel declarations start in state Comp
(which has level 1).
Annotations start in state Splice, since they are
treated very like a splice (only without a '$')
* Code compiled in state Splice (and only such code)
will be *run at compile time*, with the result replacing
the splice
* The original paper used level 1 instead of 0, etc.
* The original paper did not allow a splice within a
splice, but there is no reason not to. This is the
$ transition in the top right.
Note [Template Haskell levels]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Imported things are impLevel (= 0)
* In GHCi, variables bound by a previous command are treated
as impLevel, because we have bytecode for them.
* Variables are bound at the "current level"
* The current level starts off at outerLevel (= 1)
* The level is decremented by splicing $(..)
incremented by brackets [| |]
incremented by namequoting 'f
When a variable is used, we compare
bind: binding level, and
use: current level at usage site
Generally
bind > use Always error (bound later than used)
[| \x -> $(f x) |]
bind = use Always OK (bound same stage as used)
[| \x -> $(f [| x |]) |]
bind < use Inside brackets, it depends
Inside splice, OK
Inside neither, OK
For (bind < use) inside brackets, there are three cases:
Imported things OK f = [| map |]
Toplevel things OK g = [| f |]
Nontoplevel Only if there is a liftable instance
h = \(x:Int) -> [| x |]
See Note [What is a toplevel Id?]
Note [Quoting names]
~~~~~~~~~~~~~~~~~~~~
A quoted name 'n is a bit like a quoted expression [| n |], except that we
have no crossstage lifting (c.f. TcExpr.thBrackId). So, after incrementing
the uselevel to account for the brackets, the cases are:
bind > use Error
bind = use OK
bind < use
Imported things OK
Toplevel things OK
Nontoplevel Error
See Note [What is a toplevel Id?] in TcEnv. Examples:
f 'map
\x. f 'x
\y. [| \x. $(f 'y) |]
[| \x. $(f 'x) |]
Note [What is a toplevel Id?]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In the levelcontrol criteria above, we need to know what a "top level Id" is.
There are three kinds:
* Imported from another module (GlobalId, ExternalName)
* Bound at the top level of this module (ExternalName)
* In GHCi, bound by a previous stmt (GlobalId)
It's strange that there is no one criterion tht picks out all three, but that's
how it is right now. (The obvious thing is to give an ExternalName to GHCi Ids
bound in an earlier Stmt, but what module would you choose? See
Note [Interactivelybound Ids in GHCi] in TcRnDriver.)
The predicate we use is TcEnv.thTopLevelId.
%************************************************************************
%* *
\subsection{Main interface + stubs for the nonGHCI case
%* *
%************************************************************************
\begin{code}
tcBracket :: HsBracket Name -> BoxyRhoType -> TcM (LHsExpr TcId)
tcSpliceDecls :: LHsExpr Name -> TcM [LHsDecl RdrName]
tcSpliceExpr :: HsSplice Name -> BoxyRhoType -> TcM (HsExpr TcId)
kcSpliceType :: HsSplice Name -> TcM (HsType Name, TcKind)
lookupThName_maybe :: TH.Name -> TcM (Maybe Name)
runQuasiQuoteExpr :: HsQuasiQuote Name -> TcM (LHsExpr RdrName)
runQuasiQuotePat :: HsQuasiQuote Name -> TcM (LPat RdrName)
runAnnotation :: CoreAnnTarget -> LHsExpr Name -> TcM Annotation
#ifndef GHCI
tcBracket x _ = pprPanic "Cant do tcBracket without GHCi" (ppr x)
tcSpliceExpr e = pprPanic "Cant do tcSpliceExpr without GHCi" (ppr e)
tcSpliceDecls x = pprPanic "Cant do tcSpliceDecls without GHCi" (ppr x)
kcSpliceType x = pprPanic "Cant do kcSpliceType without GHCi" (ppr x)
lookupThName_maybe n = pprPanic "Cant do lookupThName_maybe without GHCi" (ppr n)
runQuasiQuoteExpr q = pprPanic "Cant do runQuasiQuoteExpr without GHCi" (ppr q)
runQuasiQuotePat q = pprPanic "Cant do runQuasiQuotePat without GHCi" (ppr q)
runAnnotation _ q = pprPanic "Cant do runAnnotation without GHCi" (ppr q)
#else
\end{code}
%************************************************************************
%* *
\subsection{Quoting an expression}
%* *
%************************************************************************
\begin{code}
tcBracket brack res_ty
= addErrCtxt (hang (ptext (sLit "In the Template Haskell quotation"))
2 (ppr brack)) $
do {
cur_stage <- getStage
; checkTc (not (isBrackStage cur_stage)) illegalBracket
; recordThUse
; pending_splices <- newMutVar []
; lie_var <- getLIEVar
; (meta_ty, lie) <- setStage (Brack cur_stage pending_splices lie_var)
(getLIE (tc_bracket cur_stage brack))
; tcSimplifyBracket lie
; _ <- boxyUnify meta_ty res_ty
; pendings <- readMutVar pending_splices
; return (noLoc (HsBracketOut brack pendings)) }
tc_bracket :: ThStage -> HsBracket Name -> TcM TcType
tc_bracket outer_stage (VarBr name)
= do { thing <- tcLookup name
; case thing of
AGlobal _ -> return ()
ATcId { tct_level = bind_lvl, tct_id = id }
| thTopLevelId id
-> keepAliveTc id
| otherwise
-> do { checkTc (thLevel outer_stage + 1 == bind_lvl)
(quotedNameStageErr name) }
_ -> pprPanic "th_bracket" (ppr name)
; tcMetaTy nameTyConName
}
tc_bracket _ (ExpBr expr)
= do { any_ty <- newFlexiTyVarTy liftedTypeKind
; _ <- tcMonoExprNC expr any_ty
; tcMetaTy expQTyConName }
tc_bracket _ (TypBr typ)
= do { _ <- tcHsSigTypeNC ThBrackCtxt typ
; tcMetaTy typeQTyConName }
tc_bracket _ (DecBr decls)
= do { _ <- tcTopSrcDecls emptyModDetails decls
; decl_ty <- tcMetaTy decTyConName
; q_ty <- tcMetaTy qTyConName
; return (mkAppTy q_ty (mkListTy decl_ty))
}
tc_bracket _ (PatBr _)
= failWithTc (ptext (sLit "Tempate Haskell pattern brackets are not supported yet"))
quotedNameStageErr :: Name -> SDoc
quotedNameStageErr v
= sep [ ptext (sLit "Stage error: the non-top-level quoted name") <+> ppr (VarBr v)
, ptext (sLit "must be used at the same stage at which is is bound")]
\end{code}
%************************************************************************
%* *
\subsection{Splicing an expression}
%* *
%************************************************************************
\begin{code}
tcSpliceExpr (HsSplice name expr) res_ty
= setSrcSpan (getLoc expr) $ do
{ stage <- getStage
; case stage of {
Splice -> tcTopSplice expr res_ty ;
Comp -> tcTopSplice expr res_ty ;
Brack pop_stage ps_var lie_var -> do
{ _ <- unBox res_ty
; meta_exp_ty <- tcMetaTy expQTyConName
; expr' <- setStage pop_stage $
setLIEVar lie_var $
tcMonoExpr expr meta_exp_ty
; ps <- readMutVar ps_var
; writeMutVar ps_var ((name,expr') : ps)
; return (panic "tcSpliceExpr")
}}}
tcTopSplice :: LHsExpr Name -> BoxyRhoType -> TcM (HsExpr Id)
tcTopSplice expr res_ty
= do { meta_exp_ty <- tcMetaTy expQTyConName
; zonked_q_expr <- tcTopSpliceExpr (tcMonoExpr expr meta_exp_ty)
; traceTc (text "About to run" <+> ppr zonked_q_expr)
; expr2 <- runMetaE convertToHsExpr zonked_q_expr
; traceTc (text "Got result" <+> ppr expr2)
; showSplice "expression" expr (ppr expr2)
; (exp3, _fvs) <- checkNoErrs (rnLExpr expr2)
; exp4 <- tcMonoExpr exp3 res_ty
; return (unLoc exp4) }
tcTopSpliceExpr :: TcM (LHsExpr Id) -> TcM (LHsExpr Id)
tcTopSpliceExpr tc_action
= checkNoErrs $
setStage Splice $
do {
(expr', lie) <- getLIE tc_action
; const_binds <- tcSimplifyTop lie
; zonkTopLExpr (mkHsDictLet const_binds expr') }
\end{code}
%************************************************************************
%* *
Splicing a type
%* *
%************************************************************************
Very like splicing an expression, but we don't yet share code.
\begin{code}
kcSpliceType (HsSplice name hs_expr)
= setSrcSpan (getLoc hs_expr) $ do
{ stage <- getStage
; case stage of {
Splice -> kcTopSpliceType hs_expr ;
Comp -> kcTopSpliceType hs_expr ;
Brack pop_level ps_var lie_var -> do
{ meta_ty <- tcMetaTy typeQTyConName
; expr' <- setStage pop_level $
setLIEVar lie_var $
tcMonoExpr hs_expr meta_ty
; ps <- readMutVar ps_var
; writeMutVar ps_var ((name,expr') : ps)
; kind <- newKindVar
; return (HsSpliceTyOut kind, kind)
}}}
kcTopSpliceType :: LHsExpr Name -> TcM (HsType Name, TcKind)
kcTopSpliceType expr
= do { meta_ty <- tcMetaTy typeQTyConName
; zonked_q_expr <- tcTopSpliceExpr (tcMonoExpr expr meta_ty)
; traceTc (text "About to run" <+> ppr zonked_q_expr)
; hs_ty2 <- runMetaT convertToHsType zonked_q_expr
; traceTc (text "Got result" <+> ppr hs_ty2)
; showSplice "type" expr (ppr hs_ty2)
; let doc = ptext (sLit "In the spliced type") <+> ppr hs_ty2
; hs_ty3 <- checkNoErrs (rnLHsType doc hs_ty2)
; (ty4, kind) <- kcLHsType hs_ty3
; return (unLoc ty4, kind) }
\end{code}
%************************************************************************
%* *
\subsection{Splicing an expression}
%* *
%************************************************************************
\begin{code}
tcSpliceDecls expr
= do { meta_dec_ty <- tcMetaTy decTyConName
; meta_q_ty <- tcMetaTy qTyConName
; let list_q = mkAppTy meta_q_ty (mkListTy meta_dec_ty)
; zonked_q_expr <- tcTopSpliceExpr (tcMonoExpr expr list_q)
; traceTc (text "About to run" <+> ppr zonked_q_expr)
; decls <- runMetaD convertToHsDecls zonked_q_expr
; traceTc (text "Got result" <+> vcat (map ppr decls))
; showSplice "declarations"
expr
(ppr (getLoc expr) $$ (vcat (map ppr decls)))
; return decls }
\end{code}
%************************************************************************
%* *
Annotations
%* *
%************************************************************************
\begin{code}
runAnnotation target expr = do
loc <- getSrcSpanM
data_class <- tcLookupClass dataClassName
to_annotation_wrapper_id <- tcLookupId toAnnotationWrapperName
zonked_wrapped_expr' <- tcTopSpliceExpr $
do { (expr', expr_ty) <- tcInferRhoNC expr
; wrapper <- instCall AnnOrigin [expr_ty] [mkClassPred data_class [expr_ty]]
; let specialised_to_annotation_wrapper_expr
= L loc (HsWrap wrapper (HsVar to_annotation_wrapper_id))
; return (L loc (HsApp specialised_to_annotation_wrapper_expr expr')) }
flip runMetaAW zonked_wrapped_expr' $ \annotation_wrapper ->
case annotation_wrapper of
AnnotationWrapper value | let serialized = toSerialized serializeWithData value ->
seqSerialized serialized `seq` Annotation {
ann_target = target,
ann_value = serialized
}
\end{code}
%************************************************************************
%* *
Quasiquoting
%* *
%************************************************************************
Note [Quasiquote overview]
~~~~~~~~~~~~~~~~~~~~~~~~~~~
The GHC "quasi-quote" extension is described by Geoff Mainland's paper
"Why it's nice to be quoted: quasiquoting for Haskell" (Haskell
Workshop 2007).
Briefly, one writes
[:p| stuff |]
and the arbitrary string "stuff" gets parsed by the parser 'p', whose
type should be Language.Haskell.TH.Quote.QuasiQuoter. 'p' must be
defined in another module, because we are going to run it here. It's
a bit like a TH splice:
$(p "stuff")
However, you can do this in patterns as well as terms. Becuase of this,
the splice is run by the *renamer* rather than the type checker.
\begin{code}
runQuasiQuote :: Outputable hs_syn
=> HsQuasiQuote Name
-> Name
-> String
-> Name
-> (SrcSpan -> th_syn -> Either Message hs_syn)
-> TcM hs_syn
runQuasiQuote (HsQuasiQuote _name quoter q_span quote) quote_selector desc meta_ty convert
= do {
; this_mod <- getModule
; let is_local = case nameModule_maybe quoter of
Just mod | mod == this_mod -> True
| otherwise -> False
Nothing -> True
; traceTc (text "runQQ" <+> ppr quoter <+> ppr is_local)
; checkTc (not is_local) (quoteStageError quoter)
; let quoterExpr = L q_span $! HsVar $! quoter
; let quoteExpr = L q_span $! HsLit $! HsString quote
; let expr = L q_span $
HsApp (L q_span $
HsApp (L q_span (HsVar quote_selector)) quoterExpr) quoteExpr
; meta_exp_ty <- tcMetaTy meta_ty
; zonked_q_expr <- tcTopSpliceExpr (tcMonoExpr expr meta_exp_ty)
; traceTc (text "About to run" <+> ppr zonked_q_expr)
; result <- runMetaQ convert zonked_q_expr
; traceTc (text "Got result" <+> ppr result)
; showSplice desc quoteExpr (ppr result)
; return result
}
runQuasiQuoteExpr quasiquote
= runQuasiQuote quasiquote quoteExpName "expression" expQTyConName convertToHsExpr
runQuasiQuotePat quasiquote
= runQuasiQuote quasiquote quotePatName "pattern" patQTyConName convertToPat
quoteStageError :: Name -> SDoc
quoteStageError quoter
= sep [ptext (sLit "GHC stage restriction:") <+> ppr quoter,
nest 2 (ptext (sLit "is used in a quasiquote, and must be imported, not defined locally"))]
\end{code}
%************************************************************************
%* *
\subsection{Running an expression}
%* *
%************************************************************************
\begin{code}
runMetaAW :: (AnnotationWrapper -> output)
-> LHsExpr Id
-> TcM output
runMetaAW k = runMeta False (\_ -> return . Right . k)
runQThen :: (SrcSpan -> input -> Either Message output)
-> SrcSpan
-> TH.Q input
-> TcM (Either Message output)
runQThen f expr_span what = TH.runQ what >>= (return . f expr_span)
runMetaQ :: (SrcSpan -> input -> Either Message output)
-> LHsExpr Id
-> TcM output
runMetaQ = runMeta True . runQThen
runMetaE :: (SrcSpan -> TH.Exp -> Either Message (LHsExpr RdrName))
-> LHsExpr Id
-> TcM (LHsExpr RdrName)
runMetaE = runMetaQ
runMetaP :: (SrcSpan -> TH.Pat -> Either Message (Pat RdrName))
-> LHsExpr Id
-> TcM (Pat RdrName)
runMetaP = runMetaQ
runMetaT :: (SrcSpan -> TH.Type -> Either Message (LHsType RdrName))
-> LHsExpr Id
-> TcM (LHsType RdrName)
runMetaT = runMetaQ
runMetaD :: (SrcSpan -> [TH.Dec] -> Either Message [LHsDecl RdrName])
-> LHsExpr Id
-> TcM [LHsDecl RdrName]
runMetaD = runMetaQ
runMeta :: Bool
-> (SrcSpan -> input -> TcM (Either Message output))
-> LHsExpr Id
-> TcM output
runMeta show_code run_and_convert expr
= do {
ds_expr <- initDsTc (dsLExpr expr)
; hsc_env <- getTopEnv
; src_span <- getSrcSpanM
; either_hval <- tryM $ liftIO $
HscMain.compileExpr hsc_env src_span ds_expr
; case either_hval of {
Left exn -> failWithTc (mk_msg "compile and link" exn) ;
Right hval -> do
{
let expr_span = getLoc expr
; either_tval <- tryAllM $
setSrcSpan expr_span $
do { mb_result <- run_and_convert expr_span (unsafeCoerce# hval)
; case mb_result of
Left err -> failWithTc err
Right result -> return $! result }
; case either_tval of
Right v -> return v
Left se ->
case fromException se of
Just IOEnvFailure ->
failM
_ -> failWithTc (mk_msg "run" se)
}}}
where
mk_msg s exn = vcat [text "Exception when trying to" <+> text s <+> text "compile-time code:",
nest 2 (text (Panic.showException exn)),
if show_code then nest 2 (text "Code:" <+> ppr expr) else empty]
\end{code}
Note [Exceptions in TH]
~~~~~~~~~~~~~~~~~~~~~~~
Supppose we have something like this
$( f 4 )
where
f :: Int -> Q [Dec]
f n | n>3 = fail "Too many declarations"
| otherwise = ...
The 'fail' is a usergenerated failure, and should be displayed as a
perfectly ordinary compiler error message, not a panic or anything
like that. Here's how it's processed:
* 'fail' is the monad fail. The monad instance for Q in TH.Syntax
effectively transforms (fail s) to
qReport True s >> fail
where 'qReport' comes from the Quasi class and fail from its monad
superclass.
* The TcM monad is an instance of Quasi (see TcSplice), and it implements
(qReport True s) by using addErr to add an error message to the bag of errors.
The 'fail' in TcM raises an IOEnvFailure exception
* So, when running a splice, we catch all exceptions; then for
an IOEnvFailure exception, we assume the error is already
in the errorbag (above)
other errors, we add an error to the bag
and then fail
To call runQ in the Tc monad, we need to make TcM an instance of Quasi:
\begin{code}
instance TH.Quasi (IOEnv (Env TcGblEnv TcLclEnv)) where
qNewName s = do { u <- newUnique
; let i = getKey u
; return (TH.mkNameU s i) }
qReport True msg = addErr (text msg)
qReport False msg = addReport (text msg) empty
qLocation = do { m <- getModule
; l <- getSrcSpanM
; return (TH.Loc { TH.loc_filename = unpackFS (srcSpanFile l)
, TH.loc_module = moduleNameString (moduleName m)
, TH.loc_package = packageIdString (modulePackageId m)
, TH.loc_start = (srcSpanStartLine l, srcSpanStartCol l)
, TH.loc_end = (srcSpanEndLine l, srcSpanEndCol l) }) }
qReify v = reify v
qRecover recover main = do { (msgs, mb_res) <- tryTcErrs main
; case mb_res of
Just val -> do { addMessages msgs
; return val }
Nothing -> recover
}
qRunIO io = liftIO io
\end{code}
%************************************************************************
%* *
\subsection{Errors and contexts}
%* *
%************************************************************************
\begin{code}
showSplice :: String -> LHsExpr Name -> SDoc -> TcM ()
showSplice what before after
= do { loc <- getSrcSpanM
; traceSplice (vcat [ppr loc <> colon <+> text "Splicing" <+> text what,
nest 2 (sep [nest 2 (ppr before),
text "======>",
nest 2 after])]) }
illegalBracket :: SDoc
illegalBracket = ptext (sLit "Template Haskell brackets cannot be nested (without intervening splices)")
#endif /* GHCI */
\end{code}
%************************************************************************
%* *
Reification
%* *
%************************************************************************
\begin{code}
reify :: TH.Name -> TcM TH.Info
reify th_name
= do { name <- lookupThName th_name
; thing <- tcLookupTh name
; traceIf (text "reify" <+> text (show th_name) <+> brackets (ppr_ns th_name) <+> ppr name)
; reifyThing thing
}
where
ppr_ns (TH.Name _ (TH.NameG TH.DataName _pkg _mod)) = text "data"
ppr_ns (TH.Name _ (TH.NameG TH.TcClsName _pkg _mod)) = text "tc"
ppr_ns (TH.Name _ (TH.NameG TH.VarName _pkg _mod)) = text "var"
ppr_ns _ = panic "reify/ppr_ns"
lookupThName :: TH.Name -> TcM Name
lookupThName th_name = do
mb_name <- lookupThName_maybe th_name
case mb_name of
Nothing -> failWithTc (notInScope th_name)
Just name -> return name
lookupThName_maybe th_name
= do { names <- mapMaybeM lookup (thRdrNameGuesses th_name)
; return (listToMaybe names) }
where
lookup rdr_name
= do {
; rdr_env <- getLocalRdrEnv
; case lookupLocalRdrEnv rdr_env rdr_name of
Just name -> return (Just name)
Nothing -> lookupGlobalOccRn_maybe rdr_name }
tcLookupTh :: Name -> TcM TcTyThing
tcLookupTh name
= do { (gbl_env, lcl_env) <- getEnvs
; case lookupNameEnv (tcl_env lcl_env) name of {
Just thing -> return thing;
Nothing -> do
{ if nameIsLocalOrFrom (tcg_mod gbl_env) name
then
case lookupNameEnv (tcg_type_env gbl_env) name of
Just thing -> return (AGlobal thing)
Nothing -> failWithTc (notInEnv name)
else do
{ (eps,hpt) <- getEpsAndHpt
; dflags <- getDOpts
; case lookupType dflags hpt (eps_PTE eps) name of
Just thing -> return (AGlobal thing)
Nothing -> do { thing <- tcImportDecl name
; return (AGlobal thing) }
}}}}
notInScope :: TH.Name -> SDoc
notInScope th_name = quotes (text (TH.pprint th_name)) <+>
ptext (sLit "is not in scope at a reify")
notInEnv :: Name -> SDoc
notInEnv name = quotes (ppr name) <+>
ptext (sLit "is not in the type environment at a reify")
reifyThing :: TcTyThing -> TcM TH.Info
reifyThing (AGlobal (AnId id))
= do { ty <- reifyType (idType id)
; fix <- reifyFixity (idName id)
; let v = reifyName id
; case idDetails id of
ClassOpId cls -> return (TH.ClassOpI v ty (reifyName cls) fix)
_ -> return (TH.VarI v ty Nothing fix)
}
reifyThing (AGlobal (ATyCon tc)) = reifyTyCon tc
reifyThing (AGlobal (AClass cls)) = reifyClass cls
reifyThing (AGlobal (ADataCon dc))
= do { let name = dataConName dc
; ty <- reifyType (idType (dataConWrapId dc))
; fix <- reifyFixity name
; return (TH.DataConI (reifyName name) ty
(reifyName (dataConOrigTyCon dc)) fix)
}
reifyThing (ATcId {tct_id = id, tct_type = ty})
= do { ty1 <- zonkTcType ty
; ty2 <- reifyType ty1
; fix <- reifyFixity (idName id)
; return (TH.VarI (reifyName id) ty2 Nothing fix) }
reifyThing (ATyVar tv ty)
= do { ty1 <- zonkTcType ty
; ty2 <- reifyType ty1
; return (TH.TyVarI (reifyName tv) ty2) }
reifyThing (AThing {}) = panic "reifyThing AThing"
reifyTyCon :: TyCon -> TcM TH.Info
reifyTyCon tc
| isFunTyCon tc
= return (TH.PrimTyConI (reifyName tc) 2 False)
| isPrimTyCon tc
= return (TH.PrimTyConI (reifyName tc) (tyConArity tc) (isUnLiftedTyCon tc))
| isOpenTyCon tc
= let flavour = reifyFamFlavour tc
tvs = tyConTyVars tc
kind = tyConKind tc
kind'
| isLiftedTypeKind kind = Nothing
| otherwise = Just $ reifyKind kind
in
return (TH.TyConI $
TH.FamilyD flavour (reifyName tc) (reifyTyVars tvs) kind')
| isSynTyCon tc
= do { let (tvs, rhs) = synTyConDefn tc
; rhs' <- reifyType rhs
; return (TH.TyConI $
TH.TySynD (reifyName tc) (reifyTyVars tvs) rhs')
}
reifyTyCon tc
= do { cxt <- reifyCxt (tyConStupidTheta tc)
; let tvs = tyConTyVars tc
; cons <- mapM (reifyDataCon (mkTyVarTys tvs)) (tyConDataCons tc)
; let name = reifyName tc
r_tvs = reifyTyVars tvs
deriv = []
decl | isNewTyCon tc = TH.NewtypeD cxt name r_tvs (head cons) deriv
| otherwise = TH.DataD cxt name r_tvs cons deriv
; return (TH.TyConI decl) }
reifyDataCon :: [Type] -> DataCon -> TcM TH.Con
reifyDataCon tys dc
| isVanillaDataCon dc
= do { arg_tys <- reifyTypes (dataConInstOrigArgTys dc tys)
; let stricts = map reifyStrict (dataConStrictMarks dc)
fields = dataConFieldLabels dc
name = reifyName dc
[a1,a2] = arg_tys
[s1,s2] = stricts
; ASSERT( length arg_tys == length stricts )
if not (null fields) then
return (TH.RecC name (zip3 (map reifyName fields) stricts arg_tys))
else
if dataConIsInfix dc then
ASSERT( length arg_tys == 2 )
return (TH.InfixC (s1,a1) name (s2,a2))
else
return (TH.NormalC name (stricts `zip` arg_tys)) }
| otherwise
= failWithTc (ptext (sLit "Can't reify a GADT data constructor:")
<+> quotes (ppr dc))
reifyClass :: Class -> TcM TH.Info
reifyClass cls
= do { cxt <- reifyCxt theta
; ops <- mapM reify_op op_stuff
; return (TH.ClassI $ TH.ClassD cxt (reifyName cls) (reifyTyVars tvs) fds' ops) }
where
(tvs, fds, theta, _, _, op_stuff) = classExtraBigSig cls
fds' = map reifyFunDep fds
reify_op (op, _) = do { ty <- reifyType (idType op)
; return (TH.SigD (reifyName op) ty) }
reifyType :: TypeRep.Type -> TcM TH.Type
reifyType ty@(ForAllTy _ _) = reify_for_all ty
reifyType ty@(PredTy {} `FunTy` _) = reify_for_all ty
reifyType (TyVarTy tv) = return (TH.VarT (reifyName tv))
reifyType (TyConApp tc tys) = reify_tc_app (reifyName tc) tys
reifyType (AppTy t1 t2) = do { [r1,r2] <- reifyTypes [t1,t2] ; return (r1 `TH.AppT` r2) }
reifyType (FunTy t1 t2) = do { [r1,r2] <- reifyTypes [t1,t2] ; return (TH.ArrowT `TH.AppT` r1 `TH.AppT` r2) }
reifyType ty@(PredTy {}) = pprPanic "reifyType PredTy" (ppr ty)
reify_for_all :: TypeRep.Type -> TcM TH.Type
reify_for_all ty
= do { cxt' <- reifyCxt cxt;
; tau' <- reifyType tau
; return (TH.ForallT (reifyTyVars tvs) cxt' tau') }
where
(tvs, cxt, tau) = tcSplitSigmaTy ty
reifyTypes :: [Type] -> TcM [TH.Type]
reifyTypes = mapM reifyType
reifyKind :: Kind -> TH.Kind
reifyKind ki
= let (kis, ki') = splitKindFunTys ki
kis_rep = map reifyKind kis
ki'_rep = reifyNonArrowKind ki'
in
foldr TH.ArrowK ki'_rep kis_rep
where
reifyNonArrowKind k | isLiftedTypeKind k = TH.StarK
| otherwise = pprPanic "Exotic form of kind"
(ppr k)
reifyCxt :: [PredType] -> TcM [TH.Pred]
reifyCxt = mapM reifyPred
reifyFunDep :: ([TyVar], [TyVar]) -> TH.FunDep
reifyFunDep (xs, ys) = TH.FunDep (map reifyName xs) (map reifyName ys)
reifyFamFlavour :: TyCon -> TH.FamFlavour
reifyFamFlavour tc | isOpenSynTyCon tc = TH.TypeFam
| isOpenTyCon tc = TH.DataFam
| otherwise
= panic "TcSplice.reifyFamFlavour: not a type family"
reifyTyVars :: [TyVar] -> [TH.TyVarBndr]
reifyTyVars = map reifyTyVar
where
reifyTyVar tv | isLiftedTypeKind kind = TH.PlainTV name
| otherwise = TH.KindedTV name (reifyKind kind)
where
kind = tyVarKind tv
name = reifyName tv
reify_tc_app :: TH.Name -> [TypeRep.Type] -> TcM TH.Type
reify_tc_app tc tys = do { tys' <- reifyTypes tys
; return (foldl TH.AppT (TH.ConT tc) tys') }
reifyPred :: TypeRep.PredType -> TcM TH.Pred
reifyPred (ClassP cls tys)
= do { tys' <- reifyTypes tys
; return $ TH.ClassP (reifyName cls) tys'
}
reifyPred p@(IParam _ _) = noTH (sLit "implicit parameters") (ppr p)
reifyPred (EqPred ty1 ty2)
= do { ty1' <- reifyType ty1
; ty2' <- reifyType ty2
; return $ TH.EqualP ty1' ty2'
}
reifyName :: NamedThing n => n -> TH.Name
reifyName thing
| isExternalName name = mk_varg pkg_str mod_str occ_str
| otherwise = TH.mkNameU occ_str (getKey (getUnique name))
where
name = getName thing
mod = ASSERT( isExternalName name ) nameModule name
pkg_str = packageIdString (modulePackageId mod)
mod_str = moduleNameString (moduleName mod)
occ_str = occNameString occ
occ = nameOccName name
mk_varg | OccName.isDataOcc occ = TH.mkNameG_d
| OccName.isVarOcc occ = TH.mkNameG_v
| OccName.isTcOcc occ = TH.mkNameG_tc
| otherwise = pprPanic "reifyName" (ppr name)
reifyFixity :: Name -> TcM TH.Fixity
reifyFixity name
= do { fix <- lookupFixityRn name
; return (conv_fix fix) }
where
conv_fix (BasicTypes.Fixity i d) = TH.Fixity i (conv_dir d)
conv_dir BasicTypes.InfixR = TH.InfixR
conv_dir BasicTypes.InfixL = TH.InfixL
conv_dir BasicTypes.InfixN = TH.InfixN
reifyStrict :: BasicTypes.StrictnessMark -> TH.Strict
reifyStrict MarkedStrict = TH.IsStrict
reifyStrict MarkedUnboxed = TH.IsStrict
reifyStrict NotMarkedStrict = TH.NotStrict
noTH :: LitString -> SDoc -> TcM a
noTH s d = failWithTc (hsep [ptext (sLit "Can't represent") <+> ptext s <+>
ptext (sLit "in Template Haskell:"),
nest 2 d])
\end{code}