DsMeta.hs 69.6 KB
Newer Older
1
-----------------------------------------------------------------------------
Simon Marlow's avatar
Simon Marlow committed
2
3
4
--
-- (c) The University of Glasgow 2006
--
5
6
7
8
-- The purpose of this module is to transform an HsExpr into a CoreExpr which
-- when evaluated, returns a (Meta.Q Meta.Exp) computation analogous to the
-- input HsExpr. We do this in the DsM monad, which supplies access to
-- CoreExpr's of the "smart constructors" of the Meta.Exp datatype.
9
10
11
12
13
--
-- It also defines a bunch of knownKeyNames, in the same way as is done
-- in prelude/PrelNames.  It's much more convenient to do it here, becuase
-- otherwise we have to recompile PrelNames whenever we add a Name, which is
-- a Royal Pain (triggers other recompilation).
14
15
-----------------------------------------------------------------------------

Simon Marlow's avatar
Simon Marlow committed
16
{-# OPTIONS -fno-warn-unused-imports #-}
17
18
19
-- 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
Ian Lynagh's avatar
Ian Lynagh committed
20
--     http://hackage.haskell.org/trac/ghc/wiki/Commentary/CodingStyle#Warnings
21
-- for details
22
-- The kludge is only needed in this module because of trac #2267.
23

24
25
module DsMeta( dsBracket, 
	       templateHaskellNames, qTyConName, nameTyConName,
26
27
28
	       liftName, expQTyConName, patQTyConName, decQTyConName, typeQTyConName,
	       decTyConName, typeTyConName, mkNameG_dName, mkNameG_vName, mkNameG_tcName,
	       quoteExpName, quotePatName
29
	        ) where
30

31
32
#include "HsVersions.h"

33
34
import {-# SOURCE #-}	DsExpr ( dsExpr )

Simon Marlow's avatar
Simon Marlow committed
35
import MatchLit
Simon Marlow's avatar
Simon Marlow committed
36
import DsUtils
37
38
import DsMonad

39
import qualified Language.Haskell.TH as TH
40

41
import HsSyn
Simon Marlow's avatar
Simon Marlow committed
42
43
44
45
46
47
import Class
import PrelNames
-- To avoid clashes with DsMeta.varName we must make a local alias for
-- OccName.varName we do this by removing varName from the import of
-- OccName above, making a qualified instance of OccName and using
-- OccNameAlias.varName where varName ws previously used in this file.
Simon Marlow's avatar
Simon Marlow committed
48
import qualified OccName
49

Simon Marlow's avatar
Simon Marlow committed
50
51
import Module
import Id
Simon Marlow's avatar
Simon Marlow committed
52
import Name
53
import NameEnv
Simon Marlow's avatar
Simon Marlow committed
54
55
56
import TcType
import TyCon
import TysWiredIn
57
import CoreSyn
58
import MkCore
Simon Marlow's avatar
Simon Marlow committed
59
60
61
62
import CoreUtils
import SrcLoc
import Unique
import BasicTypes
63
import Outputable
Simon Marlow's avatar
Simon Marlow committed
64
65
66
import Bag
import FastString
import ForeignCall
67

Simon Marlow's avatar
Simon Marlow committed
68
69
70
import Data.Maybe
import Control.Monad
import Data.List
Ian Lynagh's avatar
Ian Lynagh committed
71

72
73
-----------------------------------------------------------------------------
dsBracket :: HsBracket Name -> [PendingSplice] -> DsM CoreExpr
74
-- Returns a CoreExpr of type TH.ExpQ
75
76
77
-- The quoted thing is parameterised over Name, even though it has
-- been type checked.  We don't want all those type decorations!

78
79
dsBracket brack splices
  = dsExtendMetaEnv new_bit (do_brack brack)
80
  where
81
    new_bit = mkNameEnv [(n, Splice (unLoc e)) | (n,e) <- splices]
82

83
    do_brack (VarBr n)  = do { MkC e1  <- lookupOcc n ; return e1 }
84
85
    do_brack (ExpBr e)  = do { MkC e1  <- repLE e     ; return e1 }
    do_brack (PatBr p)  = do { MkC p1  <- repLP p     ; return p1 }
86
    do_brack (TypBr t)  = do { MkC t1  <- repLTy t    ; return t1 }
87
    do_brack (DecBr ds) = do { MkC ds1 <- repTopDs ds ; return ds1 }
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103

{- -------------- Examples --------------------

  [| \x -> x |]
====>
  gensym (unpackString "x"#) `bindQ` \ x1::String ->
  lam (pvar x1) (var x1)


  [| \x -> $(f [| x |]) |]
====>
  gensym (unpackString "x"#) `bindQ` \ x1::String ->
  lam (pvar x1) (f (var x1))
-}


104
105
106
107
-------------------------------------------------------
-- 			Declarations
-------------------------------------------------------

108
repTopDs :: HsGroup Name -> DsM (Core (TH.Q [TH.Dec]))
109
repTopDs group
110
 = do { let { bndrs = map unLoc (groupBinders group) } ;
111
	ss <- mkGenSyms bndrs ;
112

113
114
115
116
117
	-- Bind all the names mainly to avoid repeated use of explicit strings.
	-- Thus	we get
	--	do { t :: String <- genSym "T" ;
	--	     return (Data t [] ...more t's... }
	-- The other important reason is that the output must mention
118
	-- only "T", not "Foo:T" where Foo is the current module
119
120

	
121
	decls <- addBinds ss (do {
122
			val_ds  <- rep_val_binds (hs_valds group) ;
123
			tycl_ds <- mapM repTyClD (hs_tyclds group) ;
124
			inst_ds <- mapM repInstD' (hs_instds group) ;
125
			for_ds <- mapM repForD (hs_fords group) ;
126
			-- more needed
127
			return (de_loc $ sort_by_loc $ val_ds ++ catMaybes tycl_ds ++ inst_ds ++ for_ds) }) ;
128

129
	decl_ty <- lookupType decQTyConName ;
130
	let { core_list = coreList' decl_ty decls } ;
131
132
133

	dec_ty <- lookupType decTyConName ;
	q_decs  <- repSequenceQ dec_ty core_list ;
134
135

	wrapNongenSyms ss q_decs
136
137
138
	-- Do *not* gensym top-level binders
      }

Ian Lynagh's avatar
Ian Lynagh committed
139
groupBinders :: HsGroup Name -> [Located Name]
140
141
groupBinders (HsGroup { hs_valds = val_decls, hs_tyclds = tycl_decls,
			hs_fords = foreign_decls })
142
-- Collect the binders of a Group
143
  = collectHsValBinders val_decls ++
144
    [n | d <- tycl_decls, n <- tyClDeclNames (unLoc d)] ++
145
    [n | L _ (ForeignImport n _ _) <- foreign_decls]
146
147


148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
{- 	Note [Binders and occurrences]
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
When we desugar [d| data T = MkT |]
we want to get
	Data "T" [] [Con "MkT" []] []
and *not*
	Data "Foo:T" [] [Con "Foo:MkT" []] []
That is, the new data decl should fit into whatever new module it is
asked to fit in.   We do *not* clone, though; no need for this:
	Data "T79" ....

But if we see this:
	data T = MkT 
	foo = reifyDecl T

then we must desugar to
	foo = Data "Foo:T" [] [Con "Foo:MkT" []] []

166
167
So in repTopDs we bring the binders into scope with mkGenSyms and addBinds.
And we use lookupOcc, rather than lookupBinder
168
169
170
171
in repTyClD and repC.

-}

172
repTyClD :: LTyClDecl Name -> DsM (Maybe (SrcSpan, Core TH.DecQ))
173

174
175
176
177
repTyClD (L loc (TyData { tcdND = DataType, tcdCtxt = cxt, 
		    tcdLName = tc, tcdTyVars = tvs, 
		    tcdCons = cons, tcdDerivs = mb_derivs }))
 = do { tc1 <- lookupLOcc tc ;		-- See note [Binders and occurrences] 
178
        dec <- addTyVarBinds tvs $ \bndrs -> do {
179
      	       cxt1    <- repLContext cxt ;
180
               cons1   <- mapM repC cons ;
181
      	       cons2   <- coreList conQTyConName cons1 ;
182
      	       derivs1 <- repDerivs mb_derivs ;
183
184
	       bndrs1  <- coreList nameTyConName bndrs ;
      	       repData cxt1 tc1 bndrs1 cons2 derivs1 } ;
185
        return $ Just (loc, dec) }
186

187
188
189
190
repTyClD (L loc (TyData { tcdND = NewType, tcdCtxt = cxt, 
		    tcdLName = tc, tcdTyVars = tvs, 
		    tcdCons = [con], tcdDerivs = mb_derivs }))
 = do { tc1 <- lookupLOcc tc ;		-- See note [Binders and occurrences] 
191
        dec <- addTyVarBinds tvs $ \bndrs -> do {
192
      	       cxt1   <- repLContext cxt ;
193
194
               con1   <- repC con ;
      	       derivs1 <- repDerivs mb_derivs ;
195
196
	       bndrs1  <- coreList nameTyConName bndrs ;
      	       repNewtype cxt1 tc1 bndrs1 con1 derivs1 } ;
197
198
        return $ Just (loc, dec) }

199
200
repTyClD (L loc (TySynonym { tcdLName = tc, tcdTyVars = tvs, tcdSynRhs = ty }))
 = do { tc1 <- lookupLOcc tc ;		-- See note [Binders and occurrences] 
201
        dec <- addTyVarBinds tvs $ \bndrs -> do {
202
	       ty1     <- repLTy ty ;
203
204
	       bndrs1  <- coreList nameTyConName bndrs ;
	       repTySyn tc1 bndrs1 ty1 } ;
205
 	return (Just (loc, dec)) }
206

207
repTyClD (L loc (ClassDecl { tcdCtxt = cxt, tcdLName = cls, 
208
		      tcdTyVars = tvs, 
209
		      tcdFDs = fds,
210
211
		      tcdSigs = sigs, tcdMeths = meth_binds }))
 = do { cls1 <- lookupLOcc cls ;		-- See note [Binders and occurrences] 
212
    	dec  <- addTyVarBinds tvs $ \bndrs -> do {
213
 		  cxt1   <- repLContext cxt ;
214
 		  sigs1  <- rep_sigs sigs ;
215
 		  binds1 <- rep_binds meth_binds ;
216
	          fds1 <- repLFunDeps fds;
217
 		  decls1 <- coreList decQTyConName (sigs1 ++ binds1) ;
218
	          bndrs1 <- coreList nameTyConName bndrs ;
219
 		  repClass cxt1 cls1 bndrs1 fds1 decls1 } ;
220
    	return $ Just (loc, dec) }
221
222

-- Un-handled cases
223
repTyClD (L loc d) = putSrcSpanDs loc $
224
		     do { warnDs (hang ds_msg 4 (ppr d))
225
			; return Nothing }
226

227
228
229
230
231
232
233
234
235
236
237
238
239
-- represent fundeps
--
repLFunDeps :: [Located (FunDep Name)] -> DsM (Core [TH.FunDep])
repLFunDeps fds = do fds' <- mapM repLFunDep fds
                     fdList <- coreList funDepTyConName fds'
                     return fdList

repLFunDep :: Located (FunDep Name) -> DsM (Core TH.FunDep)
repLFunDep (L _ (xs, ys)) = do xs' <- mapM lookupBinder xs
                               ys' <- mapM lookupBinder ys
                               xs_list <- coreList nameTyConName xs'
                               ys_list <- coreList nameTyConName ys'
                               repFunDep xs_list ys_list
240

Ian Lynagh's avatar
Ian Lynagh committed
241
repInstD' :: LInstDecl Name -> DsM (SrcSpan, Core TH.DecQ)
242
repInstD' (L loc (InstDecl ty binds _ _))		-- Ignore user pragmas for now
Ian Lynagh's avatar
Ian Lynagh committed
243
 = do	{ i <- addTyVarBinds tvs $ \_ ->
244
245
246
247
248
249
250
251
252
253
254
255
256
		-- We must bring the type variables into scope, so their occurrences
		-- don't fail,  even though the binders don't appear in the resulting 
		-- data structure
		do {  cxt1 <- repContext cxt
		   ; inst_ty1 <- repPred (HsClassP cls tys)
		   ; ss <- mkGenSyms (collectHsBindBinders binds)
		   ; binds1 <- addBinds ss (rep_binds binds)
		   ; decls1 <- coreList decQTyConName binds1
		   ; decls2 <- wrapNongenSyms ss decls1
		   -- wrapNonGenSyms: do not clone the class op names!
		   -- They must be called 'op' etc, not 'op34'
		   ; repInst cxt1 inst_ty1 decls2 }

257
	; return (loc, i)}
258
 where
259
   (tvs, cxt, cls, tys) = splitHsInstDeclTy (unLoc ty)
260

261
repForD :: Located (ForeignDecl Name) -> DsM (SrcSpan, Core TH.DecQ)
262
repForD (L loc (ForeignImport name typ (CImport cc s ch cn cis)))
263
264
265
266
 = do MkC name' <- lookupLOcc name
      MkC typ' <- repLTy typ
      MkC cc' <- repCCallConv cc
      MkC s' <- repSafety s
267
      cis' <- conv_cimportspec cis
268
269
270
      MkC str <- coreStringLit $ static
                              ++ unpackFS ch ++ " "
                              ++ unpackFS cn ++ " "
271
                              ++ cis'
272
273
274
      dec <- rep2 forImpDName [cc', s', str, name', typ']
      return (loc, dec)
 where
275
276
277
278
    conv_cimportspec (CLabel cls) = notHandled "Foreign label" (doubleQuotes (ppr cls))
    conv_cimportspec (CFunction DynamicTarget) = return "dynamic"
    conv_cimportspec (CFunction (StaticTarget fs)) = return (unpackFS fs)
    conv_cimportspec CWrapper = return "wrapper"
279
280
281
    static = case cis of
                 CFunction (StaticTarget _) -> "static "
                 _ -> ""
282
repForD decl = notHandled "Foreign declaration" (ppr decl)
283
284
285
286

repCCallConv :: CCallConv -> DsM (Core TH.Callconv)
repCCallConv CCallConv = rep2 cCallName []
repCCallConv StdCallConv = rep2 stdCallName []
Ian Lynagh's avatar
Ian Lynagh committed
287
repCCallConv CmmCallConv = notHandled "repCCallConv" (ppr CmmCallConv)
288
289
290
291
292
293

repSafety :: Safety -> DsM (Core TH.Safety)
repSafety PlayRisky = rep2 unsafeName []
repSafety (PlaySafe False) = rep2 safeName []
repSafety (PlaySafe True) = rep2 threadsafeName []

Ian Lynagh's avatar
Ian Lynagh committed
294
ds_msg :: SDoc
Ian Lynagh's avatar
Ian Lynagh committed
295
ds_msg = ptext (sLit "Cannot desugar this Template Haskell declaration:")
296

297
298
299
300
-------------------------------------------------------
-- 			Constructors
-------------------------------------------------------

301
repC :: LConDecl Name -> DsM (Core TH.ConQ)
Ian Lynagh's avatar
Ian Lynagh committed
302
repC (L _ (ConDecl con _ [] (L _ []) details ResTyH98 _))
303
  = do { con1 <- lookupLOcc con ;		-- See note [Binders and occurrences] 
304
	 repConstr con1 details }
305
repC (L loc (ConDecl con expl tvs (L cloc ctxt) details ResTyH98 doc))
306
  = do { addTyVarBinds tvs $ \bndrs -> do {
307
             c' <- repC (L loc (ConDecl con expl [] (L cloc []) details ResTyH98 doc));
308
309
310
311
312
             ctxt' <- repContext ctxt;
             bndrs' <- coreList nameTyConName bndrs;
             rep2 forallCName [unC bndrs', unC ctxt', unC c']
         }
       }
313
repC (L loc con_decl)		-- GADTs
314
315
  = putSrcSpanDs loc $
    notHandled "GADT declaration" (ppr con_decl) 
316

317
repBangTy :: LBangType Name -> DsM (Core (TH.StrictTypeQ))
318
319
320
repBangTy ty= do 
  MkC s <- rep2 str []
  MkC t <- repLTy ty'
321
  rep2 strictTypeName [s, t]
322
323
324
  where 
    (str, ty') = case ty of
		   L _ (HsBangTy _ ty) -> (isStrictName,  ty)
Ian Lynagh's avatar
Ian Lynagh committed
325
		   _                   -> (notStrictName, ty)
326
327
328
329
330

-------------------------------------------------------
-- 			Deriving clause
-------------------------------------------------------

331
repDerivs :: Maybe [LHsType Name] -> DsM (Core [TH.Name])
332
repDerivs Nothing = coreList nameTyConName []
333
repDerivs (Just ctxt)
334
  = do { strs <- mapM rep_deriv ctxt ; 
335
	 coreList nameTyConName strs }
336
  where
337
    rep_deriv :: LHsType Name -> DsM (Core TH.Name)
338
	-- Deriving clauses must have the simple H98 form
339
    rep_deriv (L _ (HsPredTy (HsClassP cls []))) = lookupOcc cls
340
    rep_deriv other = notHandled "Non-H98 deriving clause" (ppr other)
341
342
343
344
345
346


-------------------------------------------------------
--   Signatures in a class decl, or a group of bindings
-------------------------------------------------------

347
rep_sigs :: [LSig Name] -> DsM [Core TH.DecQ]
348
349
350
rep_sigs sigs = do locs_cores <- rep_sigs' sigs
                   return $ de_loc $ sort_by_loc locs_cores

351
rep_sigs' :: [LSig Name] -> DsM [(SrcSpan, Core TH.DecQ)]
352
	-- We silently ignore ones we don't recognise
353
rep_sigs' sigs = do { sigs1 <- mapM rep_sig sigs ;
354
355
		     return (concat sigs1) }

356
rep_sig :: LSig Name -> DsM [(SrcSpan, Core TH.DecQ)]
357
358
	-- Singleton => Ok
	-- Empty     => Too hard, signature ignored
359
rep_sig (L loc (TypeSig nm ty)) = rep_proto nm ty loc
Ian Lynagh's avatar
Ian Lynagh committed
360
rep_sig _                       = return []
361

362
363
364
rep_proto :: Located Name -> LHsType Name -> SrcSpan -> DsM [(SrcSpan, Core TH.DecQ)]
rep_proto nm ty loc = do { nm1 <- lookupLOcc nm ; 
		       ty1 <- repLTy ty ; 
365
		       sig <- repProto nm1 ty1 ;
366
		       return [(loc, sig)] }
367
368
369
370
371


-------------------------------------------------------
-- 			Types
-------------------------------------------------------
372

chak's avatar
chak committed
373
374
-- gensym a list of type variables and enter them into the meta environment;
-- the computations passed as the second argument is executed in that extended
chak's avatar
chak committed
375
-- meta environment and gets the *new* names on Core-level as an argument
chak's avatar
chak committed
376
--
377
addTyVarBinds :: [LHsTyVarBndr Name]	         -- the binders to be added
378
379
	      -> ([Core TH.Name] -> DsM (Core (TH.Q a))) -- action in the ext env
	      -> DsM (Core (TH.Q a))
380
addTyVarBinds tvs m =
chak's avatar
chak committed
381
  do
382
    let names = map (hsTyVarName.unLoc) tvs
383
    freshNames <- mkGenSyms names
chak's avatar
chak committed
384
385
386
    term       <- addBinds freshNames $ do
		    bndrs <- mapM lookupBinder names 
		    m bndrs
387
    wrapGenSyns freshNames term
chak's avatar
chak committed
388

chak's avatar
chak committed
389
390
-- represent a type context
--
391
392
393
repLContext :: LHsContext Name -> DsM (Core TH.CxtQ)
repLContext (L _ ctxt) = repContext ctxt

394
repContext :: HsContext Name -> DsM (Core TH.CxtQ)
chak's avatar
chak committed
395
repContext ctxt = do 
396
	            preds    <- mapM repLPred ctxt
397
		    predList <- coreList typeQTyConName preds
chak's avatar
chak committed
398
		    repCtxt predList
399

chak's avatar
chak committed
400
401
-- represent a type predicate
--
402
403
404
repLPred :: LHsPred Name -> DsM (Core TH.TypeQ)
repLPred (L _ p) = repPred p

405
repPred :: HsPred Name -> DsM (Core TH.TypeQ)
chak's avatar
chak committed
406
407
repPred (HsClassP cls tys) = do
			       tcon <- repTy (HsTyVar cls)
408
			       tys1 <- repLTys tys
chak's avatar
chak committed
409
			       repTapps tcon tys1
410
repPred p@(HsEqualP _ _) = notHandled "Equational constraint" (ppr p)
411
repPred p@(HsIParam _ _) = notHandled "Implicit parameter constraint" (ppr p)
chak's avatar
chak committed
412
413
414

-- yield the representation of a list of types
--
415
416
repLTys :: [LHsType Name] -> DsM [Core TH.TypeQ]
repLTys tys = mapM repLTy tys
417

chak's avatar
chak committed
418
419
-- represent a type
--
420
421
422
repLTy :: LHsType Name -> DsM (Core TH.TypeQ)
repLTy (L _ ty) = repTy ty

423
424
425
repTy :: HsType Name -> DsM (Core TH.TypeQ)
repTy (HsForAllTy _ tvs ctxt ty)  = 
  addTyVarBinds tvs $ \bndrs -> do
426
427
    ctxt1  <- repLContext ctxt
    ty1    <- repLTy ty
428
429
    bndrs1 <- coreList nameTyConName bndrs
    repTForall bndrs1 ctxt1 ty1
430

431
repTy (HsTyVar n)
chak's avatar
chak committed
432
  | isTvOcc (nameOccName n)       = do 
433
				      tv1 <- lookupTvOcc n
chak's avatar
chak committed
434
435
436
437
438
				      repTvar tv1
  | otherwise		          = do 
				      tc1 <- lookupOcc n
				      repNamedTyCon tc1
repTy (HsAppTy f a)               = do 
439
440
				      f1 <- repLTy f
				      a1 <- repLTy a
chak's avatar
chak committed
441
442
				      repTapp f1 a1
repTy (HsFunTy f a)               = do 
443
444
				      f1   <- repLTy f
				      a1   <- repLTy a
chak's avatar
chak committed
445
446
447
				      tcon <- repArrowTyCon
				      repTapps tcon [f1, a1]
repTy (HsListTy t)		  = do
448
				      t1   <- repLTy t
chak's avatar
chak committed
449
450
451
				      tcon <- repListTyCon
				      repTapp tcon t1
repTy (HsPArrTy t)                = do
452
				      t1   <- repLTy t
453
				      tcon <- repTy (HsTyVar (tyConName parrTyCon))
chak's avatar
chak committed
454
				      repTapp tcon t1
Ian Lynagh's avatar
Ian Lynagh committed
455
repTy (HsTupleTy _ tys)	  = do
456
				      tys1 <- repLTys tys 
chak's avatar
chak committed
457
458
				      tcon <- repTupleTyCon (length tys)
				      repTapps tcon tys1
459
460
461
repTy (HsOpTy ty1 n ty2) 	  = repLTy ((nlHsTyVar (unLoc n) `nlHsAppTy` ty1) 
					   `nlHsAppTy` ty2)
repTy (HsParTy t)  	       	  = repLTy t
462
repTy (HsPredTy pred)             = repPred pred
463
464
repTy ty@(HsNumTy _)              = notHandled "Number types (for generics)" (ppr ty)
repTy ty			  = notHandled "Exotic form of type" (ppr ty)
465
466


chak's avatar
chak committed
467
-----------------------------------------------------------------------------
468
-- 		Expressions
chak's avatar
chak committed
469
-----------------------------------------------------------------------------
470

471
472
473
repLEs :: [LHsExpr Name] -> DsM (Core [TH.ExpQ])
repLEs es = do { es'  <- mapM repLE es ;
		 coreList expQTyConName es' }
474

chak's avatar
chak committed
475
476
477
-- FIXME: some of these panics should be converted into proper error messages
--	  unless we can make sure that constructs, which are plainly not
--	  supported in TH already lead to error messages at an earlier stage
478
repLE :: LHsExpr Name -> DsM (Core TH.ExpQ)
479
repLE (L loc e) = putSrcSpanDs loc (repE e)
480

481
repE :: HsExpr Name -> DsM (Core TH.ExpQ)
chak's avatar
chak committed
482
483
484
repE (HsVar x)            =
  do { mb_val <- dsLookupMetaEnv x 
     ; case mb_val of
chak's avatar
chak committed
485
	Nothing	         -> do { str <- globalVar x
chak's avatar
chak committed
486
487
488
489
			       ; repVarOrCon x str }
	Just (Bound y)   -> repVarOrCon x (coreVar y)
	Just (Splice e)  -> do { e' <- dsExpr e
			       ; return (MkC e') } }
Ian Lynagh's avatar
Ian Lynagh committed
490
repE e@(HsIPVar _) = notHandled "Implicit parameters" (ppr e)
491
492
493
494
495

	-- Remember, we're desugaring renamer output here, so
	-- HsOverlit can definitely occur
repE (HsOverLit l) = do { a <- repOverloadedLiteral l; repLit a }
repE (HsLit l)     = do { a <- repLiteral l;           repLit a }
496
repE (HsLam (MatchGroup [m] _)) = repLambda m
497
repE (HsApp x y)   = do {a <- repLE x; b <- repLE y; repApp a b}
498

Ian Lynagh's avatar
Ian Lynagh committed
499
repE (OpApp e1 op _ e2) =
500
501
502
  do { arg1 <- repLE e1; 
       arg2 <- repLE e2; 
       the_op <- repLE op ;
503
       repInfixApp arg1 the_op arg2 } 
Ian Lynagh's avatar
Ian Lynagh committed
504
repE (NegApp x _)        = do
505
			      a         <- repLE x
chak's avatar
chak committed
506
507
			      negateVar <- lookupOcc negateName >>= repVar
			      negateVar `repApp` a
508
509
510
repE (HsPar x)            = repLE x
repE (SectionL x y)       = do { a <- repLE x; b <- repLE y; repSectionL a b } 
repE (SectionR x y)       = do { a <- repLE x; b <- repLE y; repSectionR a b } 
511
512
513
repE (HsCase e (MatchGroup ms _)) = do { arg <- repLE e
				       ; ms2 <- mapM repMatchTup ms
				       ; repCaseE arg (nonEmptyCoreList ms2) }
514
515
516
517
repE (HsIf x y z)         = do
			      a <- repLE x
			      b <- repLE y
			      c <- repLE z
chak's avatar
chak committed
518
519
			      repCond a b c
repE (HsLet bs e)         = do { (ss,ds) <- repBinds bs
520
			       ; e2 <- addBinds ss (repLE e)
chak's avatar
chak committed
521
			       ; z <- repLetE ds e2
522
			       ; wrapGenSyns ss z }
chak's avatar
chak committed
523
-- FIXME: I haven't got the types here right yet
Ian Lynagh's avatar
Ian Lynagh committed
524
repE (HsDo DoExpr sts body _) 
525
 = do { (ss,zs) <- repLSts sts; 
526
	body'	<- addBinds ss $ repLE body;
527
528
	ret	<- repNoBindSt body';	
        e       <- repDoE (nonEmptyCoreList (zs ++ [ret]));
529
        wrapGenSyns ss e }
Ian Lynagh's avatar
Ian Lynagh committed
530
repE (HsDo ListComp sts body _)
531
 = do { (ss,zs) <- repLSts sts; 
532
	body'	<- addBinds ss $ repLE body;
533
534
	ret	<- repNoBindSt body';	
        e       <- repComp (nonEmptyCoreList (zs ++ [ret]));
535
        wrapGenSyns ss e }
536
repE e@(HsDo _ _ _ _) = notHandled "mdo and [: :]" (ppr e)
Ian Lynagh's avatar
Ian Lynagh committed
537
538
repE (ExplicitList _ es) = do { xs <- repLEs es; repListExp xs }
repE e@(ExplicitPArr _ _) = notHandled "Parallel arrays" (ppr e)
539
repE e@(ExplicitTuple es boxed) 
540
  | isBoxed boxed         = do { xs <- repLEs es; repTup xs }
541
  | otherwise		  = notHandled "Unboxed tuples" (ppr e)
542
repE (RecordCon c _ flds)
543
 = do { x <- lookupLOcc c;
544
545
        fs <- repFields flds;
        repRecCon x fs }
546
repE (RecordUpd e flds _ _ _)
547
 = do { x <- repLE e;
548
549
        fs <- repFields flds;
        repRecUpd x fs }
550

551
repE (ExprWithTySig e ty) = do { e1 <- repLE e; t1 <- repLTy ty; repSigExp e1 t1 }
552
repE (ArithSeq _ aseq) =
chak's avatar
chak committed
553
  case aseq of
554
    From e              -> do { ds1 <- repLE e; repFrom ds1 }
chak's avatar
chak committed
555
    FromThen e1 e2      -> do 
556
557
		             ds1 <- repLE e1
			     ds2 <- repLE e2
chak's avatar
chak committed
558
559
			     repFromThen ds1 ds2
    FromTo   e1 e2      -> do 
560
561
			     ds1 <- repLE e1
			     ds2 <- repLE e2
chak's avatar
chak committed
562
563
			     repFromTo ds1 ds2
    FromThenTo e1 e2 e3 -> do 
564
565
566
			     ds1 <- repLE e1
			     ds2 <- repLE e2
			     ds3 <- repLE e3
chak's avatar
chak committed
567
			     repFromThenTo ds1 ds2 ds3
568
569
570
571
572
repE (HsSpliceE (HsSplice n _)) 
  = do { mb_val <- dsLookupMetaEnv n
       ; case mb_val of
		 Just (Splice e) -> do { e' <- dsExpr e
				       ; return (MkC e') }
Ian Lynagh's avatar
Ian Lynagh committed
573
		 _ -> pprPanic "HsSplice" (ppr n) }
574
			-- Should not happen; statically checked
575

576
577
578
repE e@(PArrSeq {})      = notHandled "Parallel arrays" (ppr e)
repE e@(HsCoreAnn {})    = notHandled "Core annotations" (ppr e)
repE e@(HsSCC {})        = notHandled "Cost centres" (ppr e)
andy@galois.com's avatar
andy@galois.com committed
579
repE e@(HsTickPragma {}) = notHandled "Tick Pragma" (ppr e)
580
581
repE e@(HsBracketOut {}) = notHandled "TH brackets" (ppr e)
repE e 			 = notHandled "Expression form" (ppr e)
582
583
584
585

-----------------------------------------------------------------------------
-- Building representations of auxillary structures like Match, Clause, Stmt, 

586
repMatchTup ::  LMatch Name -> DsM (Core TH.MatchQ) 
Ian Lynagh's avatar
Ian Lynagh committed
587
repMatchTup (L _ (Match [p] _ (GRHSs guards wheres))) =
588
  do { ss1 <- mkGenSyms (collectPatBinders p) 
589
     ; addBinds ss1 $ do {
590
     ; p1 <- repLP p
591
     ; (ss2,ds) <- repBinds wheres
592
593
594
     ; addBinds ss2 $ do {
     ; gs    <- repGuards guards
     ; match <- repMatch p1 gs ds
595
     ; wrapGenSyns (ss1++ss2) match }}}
Ian Lynagh's avatar
Ian Lynagh committed
596
repMatchTup _ = panic "repMatchTup: case alt with more than one arg"
597

598
repClauseTup ::  LMatch Name -> DsM (Core TH.ClauseQ)
Ian Lynagh's avatar
Ian Lynagh committed
599
repClauseTup (L _ (Match ps _ (GRHSs guards wheres))) =
600
  do { ss1 <- mkGenSyms (collectPatsBinders ps) 
601
     ; addBinds ss1 $ do {
602
       ps1 <- repLPs ps
603
     ; (ss2,ds) <- repBinds wheres
604
605
606
     ; addBinds ss2 $ do {
       gs <- repGuards guards
     ; clause <- repClause ps1 gs ds
607
     ; wrapGenSyns (ss1++ss2) clause }}}
608

609
repGuards ::  [LGRHS Name] ->  DsM (Core TH.BodyQ)
610
repGuards [L _ (GRHS [] e)]
611
  = do {a <- repLE e; repNormal a }
612
repGuards other 
613
614
615
616
  = do { zs <- mapM process other;
     let {(xs, ys) = unzip zs};
	 gd <- repGuarded (nonEmptyCoreList ys);
     wrapGenSyns (concat xs) gd }
617
  where 
618
    process :: LGRHS Name -> DsM ([GenSymBind], (Core (TH.Q (TH.Guard, TH.Exp))))
619
    process (L _ (GRHS [L _ (ExprStmt e1 _ _)] e2))
620
621
           = do { x <- repLNormalGE e1 e2;
                  return ([], x) }
622
    process (L _ (GRHS ss rhs))
623
           = do (gs, ss') <- repLSts ss
624
		rhs' <- addBinds gs $ repLE rhs
625
                g <- repPatGE (nonEmptyCoreList ss') rhs'
626
                return (gs, g)
627

628
629
repFields :: HsRecordBinds Name -> DsM (Core [TH.Q TH.FieldExp])
repFields (HsRecFields { rec_flds = flds })
630
631
632
633
  = do	{ fnames <- mapM lookupLOcc (map hsRecFieldId flds)
	; es <- mapM repLE (map hsRecFieldArg flds)
	; fs <- zipWithM repFieldExp fnames es
	; coreList fieldExpQTyConName fs }
634

635
636
637

-----------------------------------------------------------------------------
-- Representing Stmt's is tricky, especially if bound variables
638
-- shadow each other. Consider:  [| do { x <- f 1; x <- f x; g x } |]
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
-- First gensym new names for every variable in any of the patterns.
-- both static (x'1 and x'2), and dynamic ((gensym "x") and (gensym "y"))
-- if variables didn't shaddow, the static gensym wouldn't be necessary
-- and we could reuse the original names (x and x).
--
-- do { x'1 <- gensym "x"
--    ; x'2 <- gensym "x"   
--    ; doE [ BindSt (pvar x'1) [| f 1 |]
--          , BindSt (pvar x'2) [| f x |] 
--          , NoBindSt [| g x |] 
--          ]
--    }

-- The strategy is to translate a whole list of do-bindings by building a
-- bigger environment, and a bigger set of meta bindings 
-- (like:  x'1 <- gensym "x" ) and then combining these with the translations
-- of the expressions within the Do
      
-----------------------------------------------------------------------------
-- The helper function repSts computes the translation of each sub expression
-- and a bunch of prefix bindings denoting the dynamic renaming.

661
662
663
repLSts :: [LStmt Name] -> DsM ([GenSymBind], [Core TH.StmtQ])
repLSts stmts = repSts (map unLoc stmts)

664
repSts :: [Stmt Name] -> DsM ([GenSymBind], [Core TH.StmtQ])
665
repSts (BindStmt p e _ _ : ss) =
666
   do { e2 <- repLE e 
667
      ; ss1 <- mkGenSyms (collectPatBinders p) 
668
      ; addBinds ss1 $ do {
669
      ; p1 <- repLP p; 
670
671
672
673
      ; (ss2,zs) <- repSts ss
      ; z <- repBindSt p1 e2
      ; return (ss1++ss2, z : zs) }}
repSts (LetStmt bs : ss) =
674
   do { (ss1,ds) <- repBinds bs
675
676
677
      ; z <- repLetSt ds
      ; (ss2,zs) <- addBinds ss1 (repSts ss)
      ; return (ss1++ss2, z : zs) } 
678
repSts (ExprStmt e _ _ : ss) =       
679
   do { e2 <- repLE e
680
681
682
      ; z <- repNoBindSt e2 
      ; (ss2,zs) <- repSts ss
      ; return (ss2, z : zs) }
683
684
repSts []    = return ([],[])
repSts other = notHandled "Exotic statement" (ppr other)
685
686


687
688
689
-----------------------------------------------------------
--			Bindings
-----------------------------------------------------------
690

691
692
693
694
695
repBinds :: HsLocalBinds Name -> DsM ([GenSymBind], Core [TH.DecQ]) 
repBinds EmptyLocalBinds
  = do	{ core_list <- coreList decQTyConName []
	; return ([], core_list) }

696
repBinds b@(HsIPBinds _) = notHandled "Implicit parameters" (ppr b)
697
698
699

repBinds (HsValBinds decs)
 = do	{ let { bndrs = map unLoc (collectHsValBinders decs) }
700
701
702
703
		-- No need to worrry about detailed scopes within
		-- the binding group, because we are talking Names
		-- here, so we can safely treat it as a mutually 
		-- recursive group
704
	; ss        <- mkGenSyms bndrs
705
706
707
	; prs       <- addBinds ss (rep_val_binds decs)
	; core_list <- coreList decQTyConName 
				(de_loc (sort_by_loc prs))
708
	; return (ss, core_list) }
709

710
rep_val_binds :: HsValBinds Name -> DsM [(SrcSpan, Core TH.DecQ)]
711
-- Assumes: all the binders of the binding are alrady in the meta-env
712
713
rep_val_binds (ValBindsOut binds sigs)
 = do { core1 <- rep_binds' (unionManyBags (map snd binds))
714
      ;	core2 <- rep_sigs' sigs
715
      ;	return (core1 ++ core2) }
Ian Lynagh's avatar
Ian Lynagh committed
716
rep_val_binds (ValBindsIn _ _)
717
 = panic "rep_val_binds: ValBindsIn"
718

719
rep_binds :: LHsBinds Name -> DsM [Core TH.DecQ]
720
721
722
723
724
rep_binds binds = do { binds_w_locs <- rep_binds' binds
		     ; return (de_loc (sort_by_loc binds_w_locs)) }

rep_binds' :: LHsBinds Name -> DsM [(SrcSpan, Core TH.DecQ)]
rep_binds' binds = mapM rep_bind (bagToList binds)
725

726
rep_bind :: LHsBind Name -> DsM (SrcSpan, Core TH.DecQ)
727
-- Assumes: all the binders of the binding are alrady in the meta-env
728
729
730
731

-- Note GHC treats declarations of a variable (not a pattern) 
-- e.g.  x = g 5 as a Fun MonoBinds. This is indicated by a single match 
-- with an empty list of patterns
732
rep_bind (L loc (FunBind { fun_id = fn, 
Ian Lynagh's avatar
Ian Lynagh committed
733
			   fun_matches = MatchGroup [L _ (Match [] _ (GRHSs guards wheres))] _ }))
734
 = do { (ss,wherecore) <- repBinds wheres
735
	; guardcore <- addBinds ss (repGuards guards)
736
737
738
739
740
	; fn'  <- lookupLBinder fn
	; p    <- repPvar fn'
	; ans  <- repVal p guardcore wherecore
	; ans' <- wrapGenSyns ss ans
	; return (loc, ans') }
741

742
rep_bind (L loc (FunBind { fun_id = fn, fun_matches = MatchGroup ms _ }))
743
 =   do { ms1 <- mapM repClauseTup ms
744
	; fn' <- lookupLBinder fn
745
        ; ans <- repFun fn' (nonEmptyCoreList ms1)
746
        ; return (loc, ans) }
747

748
rep_bind (L loc (PatBind { pat_lhs = pat, pat_rhs = GRHSs guards wheres }))
749
 =   do { patcore <- repLP pat 
750
        ; (ss,wherecore) <- repBinds wheres
751
	; guardcore <- addBinds ss (repGuards guards)
752
753
754
        ; ans  <- repVal patcore guardcore wherecore
	; ans' <- wrapGenSyns ss ans
        ; return (loc, ans') }
755

Ian Lynagh's avatar
Ian Lynagh committed
756
rep_bind (L _ (VarBind { var_id = v, var_rhs = e}))
757
 =   do { v' <- lookupBinder v 
758
	; e2 <- repLE e
759
760
        ; x <- repNormal e2
        ; patcore <- repPvar v'
761
	; empty_decls <- coreList decQTyConName [] 
762
        ; ans <- repVal patcore x empty_decls
763
        ; return (srcLocSpan (getSrcLoc v), ans) }
764

Ian Lynagh's avatar
Ian Lynagh committed
765
rep_bind (L _ (AbsBinds {})) = panic "rep_bind: AbsBinds"
766

767
-----------------------------------------------------------------------------
768
-- Since everything in a Bind is mutually recursive we need rename all
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
-- all the variables simultaneously. For example: 
-- [| AndMonoBinds (f x = x + g 2) (g x = f 1 + 2) |] would translate to
-- do { f'1 <- gensym "f"
--    ; g'2 <- gensym "g"
--    ; [ do { x'3 <- gensym "x"; fun f'1 [pvar x'3] [| x + g2 |]},
--        do { x'4 <- gensym "x"; fun g'2 [pvar x'4] [| f 1 + 2 |]}
--      ]}
-- This requires collecting the bindings (f'1 <- gensym "f"), and the 
-- environment ( f |-> f'1 ) from each binding, and then unioning them 
-- together. As we do this we collect GenSymBinds's which represent the renamed 
-- variables bound by the Bindings. In order not to lose track of these 
-- representations we build a shadow datatype MB with the same structure as 
-- MonoBinds, but which has slots for the representations


-----------------------------------------------------------------------------
785
-- GHC allows a more general form of lambda abstraction than specified
786
787
788
789
790
-- by Haskell 98. In particular it allows guarded lambda's like : 
-- (\  x | even x -> 0 | odd x -> 1) at the moment we can't represent this in
-- Haskell Template's Meta.Exp type so we punt if it isn't a simple thing like
-- (\ p1 .. pn -> exp) by causing an error.  

791
repLambda :: LMatch Name -> DsM (Core TH.ExpQ)
792
repLambda (L _ (Match ps _ (GRHSs [L _ (GRHS [] e)] EmptyLocalBinds)))
793
 = do { let bndrs = collectPatsBinders ps ;
794
      ; ss  <- mkGenSyms bndrs
795
      ; lam <- addBinds ss (
796
		do { xs <- repLPs ps; body <- repLE e; repLam xs body })
797
      ; wrapGenSyns ss lam }
798

799
repLambda (L _ m) = notHandled "Guarded labmdas" (pprMatch (LambdaExpr :: HsMatchContext Name) m)
800
801
802

  
-----------------------------------------------------------------------------
803
--			Patterns
804
805
806
807
808
809
-- repP deals with patterns.  It assumes that we have already
-- walked over the pattern(s) once to collect the binders, and 
-- have extended the environment.  So every pattern-bound 
-- variable should already appear in the environment.

-- Process a list of patterns
810
repLPs :: [LPat Name] -> DsM (Core [TH.PatQ])
811
repLPs ps = do { ps' <- mapM repLP ps ;
812
		 coreList patQTyConName ps' }
813

814
repLP :: LPat Name -> DsM (Core TH.PatQ)
815
repLP (L _ p) = repP p
816

817
repP :: Pat Name -> DsM (Core TH.PatQ)
818
819
820
821
822
823
824
825
repP (WildPat _)       = repPwild 
repP (LitPat l)        = do { l2 <- repLiteral l; repPlit l2 }
repP (VarPat x)        = do { x' <- lookupBinder x; repPvar x' }
repP (LazyPat p)       = do { p1 <- repLP p; repPtilde p1 }
repP (AsPat x p)       = do { x' <- lookupLBinder x; p1 <- repLP p; repPaspat x' p1 }
repP (ParPat p)        = repLP p 
repP (ListPat ps _)    = do { qs <- repLPs ps; repPlist qs }
repP (TuplePat ps _ _) = do { qs <- repLPs ps; repPtup qs }
826
repP (ConPatIn dc details)
827
 = do { con_str <- lookupLOcc dc
828
      ; case details of
829
830
831
832
         PrefixCon ps -> do { qs <- repLPs ps; repPcon con_str qs }
         RecCon rec   -> do { let flds = rec_flds rec
			    ; vs <- sequence $ map lookupLOcc (map hsRecFieldId flds)
                            ; ps <- sequence $ map repLP (map hsRecFieldArg flds)
833
                            ; fps <- zipWithM (\x y -> rep2 fieldPatName [unC x,unC y]) vs ps
834
                            ; fps' <- coreList fieldPatQTyConName fps
835
                            ; repPrec con_str fps' }
836
837
838
         InfixCon p1 p2 -> do { p1' <- repLP p1;
                                p2' <- repLP p2;
                                repPinfix p1' con_str p2' }
839
   }
840
repP (NPat l Nothing _)  = do { a <- repOverloadedLiteral l; repPlit a }
Ian Lynagh's avatar
Ian Lynagh committed
841
repP p@(NPat _ (Just _) _) = notHandled "Negative overloaded patterns" (ppr p)
842
843
844
845
846
847
848
849
850
repP p@(SigPatIn {})  = notHandled "Type signatures in patterns" (ppr p)
	-- The problem is to do with scoped type variables.
	-- To implement them, we have to implement the scoping rules
	-- here in DsMeta, and I don't want to do that today!
	--	 do { p' <- repLP p; t' <- repLTy t; repPsig p' t' }
	--	repPsig :: Core TH.PatQ -> Core TH.TypeQ -> DsM (Core TH.PatQ)
	--	repPsig (MkC p) (MkC t) = rep2 sigPName [p, t]

repP other = notHandled "Exotic pattern" (ppr other)
851

852
853
854
----------------------------------------------------------
-- Declaration ordering helpers

855
sort_by_loc :: [(SrcSpan, a)] -> [(SrcSpan, a)]
856
857
858
sort_by_loc xs = sortBy comp xs
    where comp x y = compare (fst x) (fst y)

859
de_loc :: [(a, b)] -> [b]