Syntax.hs 43 KB
Newer Older
1
{-# LANGUAGE UnboxedTuples #-}
Ian Lynagh's avatar
Ian Lynagh committed
2
{-# OPTIONS_GHC -fno-warn-warnings-deprecations #-}
3
-- The -fno-warn-warnings-deprecations flag is a temporary kludge.
Ian Lynagh's avatar
Ian Lynagh committed
4 5 6 7
-- 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/WorkingConventions#Warnings
-- for details
8

9 10 11 12 13 14 15 16 17 18 19 20 21 22
-----------------------------------------------------------------------------
-- |
-- Module      :  Language.Haskell.Syntax
-- Copyright   :  (c) The University of Glasgow 2003
-- License     :  BSD-style (see the file libraries/base/LICENSE)
-- 
-- Maintainer  :  libraries@haskell.org
-- Stability   :  experimental
-- Portability :  portable
--
-- Abstract syntax definitions for Template Haskell.
--
-----------------------------------------------------------------------------

23
module Language.Haskell.TH.Syntax where
24 25 26

import GHC.Base		( Int(..), Int#, (<#), (==#) )

27
import Data.Data (Data(..), Typeable, mkConstr, mkDataType, constrIndex)
Ross Paterson's avatar
Ross Paterson committed
28
import qualified Data.Data as Data
29
import Control.Applicative( Applicative(..) )
30
import Data.IORef
31
import System.IO.Unsafe	( unsafePerformIO )
32
import Control.Monad (liftM)
33
import System.IO	( hPutStrLn, stderr )
34
import Data.Char        ( isAlpha )
reinerp's avatar
reinerp committed
35
import Data.Word        ( Word8 )
36 37 38 39 40 41 42

-----------------------------------------------------
--
--		The Quasi class
--
-----------------------------------------------------

43
class (Monad m, Applicative m) => Quasi m where
44
  qNewName :: String -> m Name
aavogt's avatar
aavogt committed
45
	-- ^ Fresh names
46 47

	-- Error reporting and recovery
aavogt's avatar
aavogt committed
48
  qReport  :: Bool -> String -> m ()	-- ^ Report an error (True) or warning (False)
49
					-- ...but carry on; use 'fail' to stop
aavogt's avatar
aavogt committed
50 51 52
  qRecover :: m a -- ^ the error handler
           -> m a -- ^ action which may fail
           -> m a		-- ^ Recover from the monadic 'fail'
53 54
 
	-- Inspect the type-checker's environment
55 56 57 58 59 60 61 62
  qLookupName :: Bool -> String -> m (Maybe Name)
       -- True <=> type namespace, False <=> value namespace
  qReify          :: Name -> m Info
  qReifyInstances :: Name -> [Type] -> m [Dec]
       -- Is (n tys) an instance?
       -- Returns list of matching instance Decs 
       --    (with empty sub-Decs)
       -- Works for classes and type functions
63

64
  qLocation :: m Loc
65 66

  qRunIO :: IO a -> m a
aavogt's avatar
aavogt committed
67
  -- ^ Input/output (dangerous)
68

GregWeber's avatar
GregWeber committed
69
  qAddDependentFile :: FilePath -> m ()
70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89

-----------------------------------------------------
--	The IO instance of Quasi
-- 
--  This instance is used only when running a Q
--  computation in the IO monad, usually just to
--  print the result.  There is no interesting
--  type environment, so reification isn't going to
--  work.
--
-----------------------------------------------------

instance Quasi IO where
  qNewName s = do { n <- readIORef counter
                 ; writeIORef counter (n+1)
                 ; return (mkNameU s n) }

  qReport True  msg = hPutStrLn stderr ("Template Haskell error: " ++ msg)
  qReport False msg = hPutStrLn stderr ("Template Haskell error: " ++ msg)

90
  qLookupName _ _     = badIO "lookupName"
91
  qReify _            = badIO "reify"
92
  qReifyInstances _ _ = badIO "classInstances"
93 94
  qLocation    	      = badIO "currentLocation"
  qRecover _ _ 	      = badIO "recover" -- Maybe we could fix this?
GregWeber's avatar
GregWeber committed
95
  qAddDependentFile _ = badIO "addDependentFile"
96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116

  qRunIO m = m
  
badIO :: String -> IO a
badIO op = do	{ qReport True ("Can't do `" ++ op ++ "' in the IO monad")
		; fail "Template Haskell failure" }

-- Global variable to generate unique symbols
counter :: IORef Int
{-# NOINLINE counter #-}
counter = unsafePerformIO (newIORef 0)


-----------------------------------------------------
--
--		The Q monad
--
-----------------------------------------------------

newtype Q a = Q { unQ :: forall m. Quasi m => m a }

117 118 119 120 121 122 123 124 125 126 127
-- \"Runs\" the 'Q' monad. Normal users of Template Haskell
-- should not need this function, as the splice brackets @$( ... )@
-- are the usual way of running a 'Q' computation.
--
-- This function is primarily used in GHC internals, and for debugging
-- splices by running them in 'IO'. 
--
-- Note that many functions in 'Q', such as 'reify' and other compiler
-- queries, are not supported when running 'Q' in 'IO'; these operations
-- simply fail at runtime. Indeed, the only operations guaranteed to succeed
-- are 'newName', 'runIO', 'reportError' and 'reportWarning'.
128 129 130 131 132 133 134
runQ :: Quasi m => Q a -> m a
runQ (Q m) = m

instance Monad Q where
  return x   = Q (return x)
  Q m >>= k  = Q (m >>= \x -> unQ (k x))
  Q m >> Q n = Q (m >> n)
135
  fail s     = report True s >> Q (fail "Q monad failure")
136

137 138 139
instance Functor Q where
  fmap f (Q x) = Q (fmap f x)

140 141 142 143
instance Applicative Q where 
  pure x = Q (pure x) 
  Q f <*> Q x = Q (f <*> x) 

144 145
----------------------------------------------------
-- Packaged versions for the programmer, hiding the Quasi-ness
146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180

{- | 
Generate a fresh name, which cannot be captured. 

For example, this:

@f = $(do
  nm1 <- newName \"x\"
  let nm2 = 'mkName' \"x\"
  return ('LamE' ['VarP' nm1] (LamE [VarP nm2] ('VarE' nm1)))
 )@

will produce the splice

>f = \x0 -> \x -> x0

In particular, the occurrence @VarE nm1@ refers to the binding @VarP nm1@,
and is not captured by the binding @VarP nm2@.

Although names generated by @newName@ cannot /be captured/, they can
/capture/ other names. For example, this:

>g = $(do
>  nm1 <- newName "x"
>  let nm2 = mkName "x"
>  return (LamE [VarP nm2] (LamE [VarP nm1] (VarE nm2)))
> )

will produce the splice

>g = \x -> \x0 -> x0

since the occurrence @VarE nm2@ is captured by the innermost binding
of @x@, namely @VarP nm1@.
-}
181 182 183
newName :: String -> Q Name
newName s = Q (qNewName s)

184 185
-- | Report an error (True) or warning (False), 
-- but carry on; use 'fail' to stop.
186 187 188
report  :: Bool -> String -> Q ()
report b s = Q (qReport b s)

189 190 191
-- | Recover from errors raised by 'reportError' or 'fail'.
recover :: Q a -- ^ handler to invoke on failure
        -> Q a -- ^ computation to run
aavogt's avatar
aavogt committed
192
        -> Q a
193 194
recover (Q r) (Q m) = Q (qRecover r m)

195 196 197 198 199
-- We don't export lookupName; the Bool isn't a great API
-- Instead we export lookupTypeName, lookupValueName
lookupName :: Bool -> String -> Q (Maybe Name)
lookupName ns s = Q (qLookupName ns s)

200 201
-- | Look up the given name in the (type namespace of the) current splice's scope. See "Language.Haskell.TH.Syntax#namelookup" for more details.
lookupTypeName :: String -> Q (Maybe Name)
202
lookupTypeName  s = Q (qLookupName True s)
203 204 205

-- | Look up the given name in the (value namespace of the) current splice's scope. See "Language.Haskell.TH.Syntax#namelookup" for more details.
lookupValueName :: String -> Q (Maybe Name)
206 207
lookupValueName s = Q (qLookupName False s)

208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276
{-
Note [Name lookup]
~~~~~~~~~~~~~~~~~~
-}
{- $namelookup #namelookup#
The functions 'lookupTypeName' and 'lookupValueName' provide
a way to query the current splice's context for what names
are in scope. The function 'lookupTypeName' queries the type
namespace, whereas 'lookupValueName' queries the value namespace,
but the functions are otherwise identical.

A call @lookupValueName s@ will check if there is a value
with name @s@ in scope at the current splice's location. If
there is, the @Name@ of this value is returned;
if not, then @Nothing@ is returned.

The returned name cannot be \"captured\". 
For example:

> f = "global"
> g = $( do
>          Just nm <- lookupValueName "f"
>          [| let f = "local" in $( varE nm ) |]

In this case, @g = \"global\"@; the call to @lookupValueName@
returned the global @f@, and this name was /not/ captured by
the local definition of @f@.

The lookup is performed in the context of the /top-level/ splice
being run. For example:

> f = "global"
> g = $( [| let f = "local" in 
>            $(do
>                Just nm <- lookupValueName "f"
>                varE nm
>             ) |] )

Again in this example, @g = \"global\"@, because the call to
@lookupValueName@ queries the context of the outer-most @$(...)@.

Operators should be queried without any surrounding parentheses, like so:

> lookupValueName "+"

Qualified names are also supported, like so:

> lookupValueName "Prelude.+"
> lookupValueName "Prelude.map"

-}


{- | 'reify' looks up information about the 'Name'.

It is sometimes useful to construct the argument name using 'lookupTypeName' or 'lookupValueName'
to ensure that we are reifying from the right namespace. For instance, in this context:

> data D = D

which @D@ does @reify (mkName \"D\")@ return information about? (Answer: @D@-the-type, but don't rely on it.)
To ensure we get information about @D@-the-value, use 'lookupValueName':

> do
>   Just nm <- lookupValueName "D"
>   reify nm

and to get information about @D@-the-type, use 'lookupTypeName'.
-}
277 278 279
reify :: Name -> Q Info
reify v = Q (qReify v)

280 281 282 283 284 285
{- | @reifyInstances nm tys@ returns a list of visible instances of @nm tys@. That is, 
if @nm@ is the name of a type class, then all instances of this class at the types @tys@
are returned. Alternatively, if @nm@ is the name of a data family or type family,
all instances of this family at the types @tys@ are returned.
-}
reifyInstances :: Name -> [Type] -> Q [InstanceDec]
286
reifyInstances cls tys = Q (qReifyInstances cls tys)
287

288
-- | Is the list of instances returned by 'reifyInstances' nonempty?
289 290 291
isInstance :: Name -> [Type] -> Q Bool
isInstance nm tys = do { decs <- reifyInstances nm tys
                       ; return (not (null decs)) }
292

293
-- | The location at which this computation is spliced.
294 295
location :: Q Loc
location = Q qLocation
296

dons's avatar
dons committed
297
-- |The 'runIO' function lets you run an I\/O computation in the 'Q' monad.
298 299 300 301 302 303
-- Take care: you are guaranteed the ordering of calls to 'runIO' within 
-- a single 'Q' computation, but not about the order in which splices are run.  
--
-- Note: for various murky reasons, stdout and stderr handles are not 
-- necesarily flushed when the  compiler finishes running, so you should
-- flush them yourself.
304 305 306
runIO :: IO a -> Q a
runIO m = Q (qRunIO m)

GregWeber's avatar
GregWeber committed
307 308 309 310 311 312 313
-- | Record external files that runIO is using (dependent upon).
-- The compiler can then recognize that it should re-compile the file using this TH when the external file changes.
-- Note that ghc -M will still not know about these dependencies - it does not execute TH.
-- Expects an absolute file path.
addDependentFile :: FilePath -> Q ()
addDependentFile fp = Q (qAddDependentFile fp)

314
instance Quasi Q where
GregWeber's avatar
GregWeber committed
315 316 317 318 319 320 321 322 323
  qNewName  	    = newName
  qReport   	    = report
  qRecover  	    = recover 
  qReify    	    = reify
  qReifyInstances   = reifyInstances
  qLookupName       = lookupName
  qLocation 	    = location
  qRunIO    	    = runIO
  qAddDependentFile = addDependentFile
324 325 326 327


----------------------------------------------------
-- The following operations are used solely in DsMeta when desugaring brackets
328
-- They are not necessary for the user, who can use ordinary return and (>>=) etc
329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361

returnQ :: a -> Q a
returnQ = return

bindQ :: Q a -> (a -> Q b) -> Q b
bindQ = (>>=)

sequenceQ :: [Q a] -> Q [a]
sequenceQ = sequence


-----------------------------------------------------
--
--		The Lift class
--
-----------------------------------------------------

class Lift t where
  lift :: t -> Q Exp
  
instance Lift Integer where
  lift x = return (LitE (IntegerL x))

instance Lift Int where
  lift x= return (LitE (IntegerL (fromIntegral x)))

instance Lift Char where
  lift x = return (LitE (CharL x))

instance Lift Bool where
  lift True  = return (ConE trueName)
  lift False = return (ConE falseName)

362 363 364 365 366 367 368 369
instance Lift a => Lift (Maybe a) where
  lift Nothing  = return (ConE nothingName)
  lift (Just x) = liftM (ConE justName `AppE`) (lift x)

instance (Lift a, Lift b) => Lift (Either a b) where
  lift (Left x)  = liftM (ConE leftName  `AppE`) (lift x)
  lift (Right y) = liftM (ConE rightName `AppE`) (lift y)

370 371 372
instance Lift a => Lift [a] where
  lift xs = do { xs' <- mapM lift xs; return (ListE xs') }

373 374 375 376
liftString :: String -> Q Exp
-- Used in TcExpr to short-circuit the lifting for strings
liftString s = return (LitE (StringL s))

377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403
instance (Lift a, Lift b) => Lift (a, b) where
  lift (a, b)
    = liftM TupE $ sequence [lift a, lift b]

instance (Lift a, Lift b, Lift c) => Lift (a, b, c) where
  lift (a, b, c)
    = liftM TupE $ sequence [lift a, lift b, lift c]

instance (Lift a, Lift b, Lift c, Lift d) => Lift (a, b, c, d) where
  lift (a, b, c, d)
    = liftM TupE $ sequence [lift a, lift b, lift c, lift d]

instance (Lift a, Lift b, Lift c, Lift d, Lift e)
      => Lift (a, b, c, d, e) where
  lift (a, b, c, d, e)
    = liftM TupE $ sequence [lift a, lift b, lift c, lift d, lift e]

instance (Lift a, Lift b, Lift c, Lift d, Lift e, Lift f)
      => Lift (a, b, c, d, e, f) where
  lift (a, b, c, d, e, f)
    = liftM TupE $ sequence [lift a, lift b, lift c, lift d, lift e, lift f]

instance (Lift a, Lift b, Lift c, Lift d, Lift e, Lift f, Lift g)
      => Lift (a, b, c, d, e, f, g) where
  lift (a, b, c, d, e, f, g)
    = liftM TupE $ sequence [lift a, lift b, lift c, lift d, lift e, lift f, lift g]

404 405 406 407 408 409 410 411 412 413
-- TH has a special form for literal strings,
-- which we should take advantage of.
-- NB: the lhs of the rule has no args, so that
--     the rule will apply to a 'lift' all on its own
--     which happens to be the way the type checker 
--     creates it.
{-# RULES "TH:liftString" lift = \s -> return (LitE (StringL s)) #-}


trueName, falseName :: Name
Ian Lynagh's avatar
Ian Lynagh committed
414 415
trueName  = mkNameG DataName "ghc-prim" "GHC.Types" "True"
falseName = mkNameG DataName "ghc-prim" "GHC.Types" "False"
416

417 418 419 420 421 422 423 424
nothingName, justName :: Name
nothingName = mkNameG DataName "base" "Data.Maybe" "Nothing"
justName    = mkNameG DataName "base" "Data.Maybe" "Just"

leftName, rightName :: Name
leftName  = mkNameG DataName "base" "Data.Either" "Left"
rightName = mkNameG DataName "base" "Data.Either" "Right"

425 426 427 428 429

-----------------------------------------------------
--		Names and uniques 
-----------------------------------------------------

430 431 432 433 434 435 436 437 438
newtype ModName = ModName String	-- Module name
 deriving (Eq,Ord,Typeable,Data)

newtype PkgName = PkgName String	-- package name
 deriving (Eq,Ord,Typeable,Data)

newtype OccName = OccName String
 deriving (Eq,Ord,Typeable,Data)

439
mkModName :: String -> ModName
440
mkModName s = ModName s
441 442

modString :: ModName -> String
443
modString (ModName m) = m
444

445 446

mkPkgName :: String -> PkgName
447
mkPkgName s = PkgName s
448 449

pkgString :: PkgName -> String
450
pkgString (PkgName m) = m
451 452


453 454 455 456 457
-----------------------------------------------------
--		OccName
-----------------------------------------------------

mkOccName :: String -> OccName
458
mkOccName s = OccName s
459 460

occString :: OccName -> String
461
occString (OccName occ) = occ
462 463 464 465 466


-----------------------------------------------------
--		 Names
-----------------------------------------------------
467
-- 
aavogt's avatar
aavogt committed
468
-- For "global" names ('NameG') we need a totally unique name,
469 470
-- so we must include the name-space of the thing
--
aavogt's avatar
aavogt committed
471
-- For unique-numbered things ('NameU'), we've got a unique reference
472 473
-- anyway, so no need for name space
--
aavogt's avatar
aavogt committed
474
-- For dynamically bound thing ('NameS') we probably want them to
475 476
-- in a context-dependent way, so again we don't want the name
-- space.  For example:
aavogt's avatar
aavogt committed
477 478 479
--
-- > let v = mkName "T" in [| data $v = $v |]
--
480
-- Here we use the same Name for both type constructor and data constructor
aavogt's avatar
aavogt committed
481 482 483 484 485 486 487 488 489 490
--
--
-- NameL and NameG are bound *outside* the TH syntax tree
-- either globally (NameG) or locally (NameL). Ex:
--
-- > f x = $(h [| (map, x) |])
--
-- The 'map' will be a NameG, and 'x' wil be a NameL
--
-- These Names should never appear in a binding position in a TH syntax tree
491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547

{- $namecapture #namecapture#
Much of 'Name' API is concerned with the problem of /name capture/, which
can be seen in the following example.

> f expr = [| let x = 0 in $expr |]
> ...
> g x = $( f [| x |] )
> h y = $( f [| y |] )

A naive desugaring of this would yield:

> g x = let x = 0 in x
> h y = let x = 0 in y

All of a sudden, @g@ and @h@ have different meanings! In this case,
we say that the @x@ in the RHS of @g@ has been /captured/
by the binding of @x@ in @f@.

What we actually want is for the @x@ in @f@ to be distinct from the
@x@ in @g@, so we get the following desugaring:

> g x = let x' = 0 in x
> h y = let x' = 0 in y

which avoids name capture as desired. 

In the general case, we say that a @Name@ can be captured if
the thing it refers to can be changed by adding new declarations.
-}

{- |
An abstract type representing names in the syntax tree.

'Name's can be constructed in several ways, which come with different
name-capture guarantees (see "Language.Haskell.TH.Syntax#namecapture" for
an explanation of name capture):

  * the built-in syntax @'f@ and @''T@ can be used to construct names, 
    The expression @'f@ gives a @Name@ which refers to the value @f@ 
    currently in scope, and @''T@ gives a @Name@ which refers to the
    type @T@ currently in scope. These names can never be captured.
    
  * 'lookupValueName' and 'lookupTypeName' are similar to @'f@ and 
     @''T@ respectively, but the @Name@s are looked up at the point
     where the current splice is being run. These names can never be
     captured.

  * 'newName' monadically generates a new name, which can never
     be captured.
     
  * 'mkName' generates a capturable name.

Names constructed using @newName@ and @mkName@ may be used in bindings
(such as @let x = ...@ or @\x -> ...@), but names constructed using
@lookupValueName@, @lookupTypeName@, @'f@, @''T@ may not.
-}
548
data Name = Name OccName NameFlavour deriving (Typeable, Data)
549 550

data NameFlavour
aavogt's avatar
aavogt committed
551 552 553 554 555 556
  = NameS           -- ^ An unqualified name; dynamically bound
  | NameQ ModName   -- ^ A qualified name; dynamically bound
  | NameU Int#      -- ^ A unique local name
  | NameL Int#      -- ^ Local name bound outside of the TH AST
  | NameG NameSpace PkgName ModName -- ^ Global name bound outside of the TH AST:
                -- An original name (occurrences only, not binders)
557 558
		-- Need the namespace too to be sure which 
		-- thing we are naming
559 560
  deriving ( Typeable )

aavogt's avatar
aavogt committed
561
-- |
562 563 564 565 566 567 568 569 570 571
-- Although the NameFlavour type is abstract, the Data instance is not. The reason for this
-- is that currently we use Data to serialize values in annotations, and in order for that to
-- work for Template Haskell names introduced via the 'x syntax we need gunfold on NameFlavour
-- to work. Bleh!
--
-- The long term solution to this is to use the binary package for annotation serialization and
-- then remove this instance. However, to do _that_ we need to wait on binary to become stable, since
-- boot libraries cannot be upgraded seperately from GHC itself.
--
-- This instance cannot be derived automatically due to bug #2701
572
instance Data NameFlavour where
573 574 575 576 577 578 579 580 581 582 583 584
     gfoldl _ z NameS          = z NameS
     gfoldl k z (NameQ mn)     = z NameQ `k` mn
     gfoldl k z (NameU i)      = z (\(I# i') -> NameU i') `k` (I# i)
     gfoldl k z (NameL i)      = z (\(I# i') -> NameL i') `k` (I# i)
     gfoldl k z (NameG ns p m) = z NameG `k` ns `k` p `k` m
     gunfold k z c = case constrIndex c of
         1 -> z NameS
         2 -> k $ z NameQ
         3 -> k $ z (\(I# i) -> NameU i)
         4 -> k $ z (\(I# i) -> NameL i)
         5 -> k $ k $ k $ z NameG
         _ -> error "gunfold: NameFlavour"
585 586 587 588 589 590 591
     toConstr NameS = con_NameS
     toConstr (NameQ _) = con_NameQ
     toConstr (NameU _) = con_NameU
     toConstr (NameL _) = con_NameL
     toConstr (NameG _ _ _) = con_NameG
     dataTypeOf _ = ty_NameFlavour

Ross Paterson's avatar
Ross Paterson committed
592 593 594 595 596 597
con_NameS, con_NameQ, con_NameU, con_NameL, con_NameG :: Data.Constr
con_NameS = mkConstr ty_NameFlavour "NameS" [] Data.Prefix
con_NameQ = mkConstr ty_NameFlavour "NameQ" [] Data.Prefix
con_NameU = mkConstr ty_NameFlavour "NameU" [] Data.Prefix
con_NameL = mkConstr ty_NameFlavour "NameL" [] Data.Prefix
con_NameG = mkConstr ty_NameFlavour "NameG" [] Data.Prefix
Ian Lynagh's avatar
Ian Lynagh committed
598

Ross Paterson's avatar
Ross Paterson committed
599
ty_NameFlavour :: Data.DataType
600 601 602
ty_NameFlavour = mkDataType "Language.Haskell.TH.Syntax.NameFlavour"
                            [con_NameS, con_NameQ, con_NameU,
                             con_NameL, con_NameG]
603

aavogt's avatar
aavogt committed
604 605 606
data NameSpace = VarName	-- ^ Variables
	       | DataName	-- ^ Data constructors 
	       | TcClsName	-- ^ Type constructors and classes; Haskell has them
607
				-- in the same name space for now.
608
	       deriving( Eq, Ord, Data, Typeable )
609 610 611

type Uniq = Int

612
-- | The name without its module prefix
613 614 615
nameBase :: Name -> String
nameBase (Name occ _) = occString occ

616
-- | Module prefix of a name, if it exists
617
nameModule :: Name -> Maybe String
Ian Lynagh's avatar
Ian Lynagh committed
618
nameModule (Name _ (NameQ m))     = Just (modString m)
619
nameModule (Name _ (NameG _ _ m)) = Just (modString m)
Ian Lynagh's avatar
Ian Lynagh committed
620
nameModule _                      = Nothing
621

622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645
{- | 
Generate a capturable name. Occurrences of such names will be
resolved according to the Haskell scoping rules at the occurrence
site.

For example:

> f = [| pi + $(varE (mkName "pi")) |]
> ...
> g = let pi = 3 in $f

In this case, @g@ is desugared to

> g = Prelude.pi + 3

Note that @mkName@ may be used with qualified names:

> mkName "Prelude.pi"

See also 'Language.Haskell.TH.Lib.dyn' for a useful combinator. The above example could
be rewritten using 'dyn' as

> f = [| pi + $(dyn "pi") |]
-}
646
mkName :: String -> Name
647
-- The string can have a '.', thus "Foo.baz",
648 649 650 651 652 653
-- giving a dynamically-bound qualified name,
-- in which case we want to generate a NameQ
--
-- Parse the string to see if it has a "." in it
-- so we know whether to generate a qualified or unqualified name
-- It's a bit tricky because we need to parse 
aavogt's avatar
aavogt committed
654 655 656
--
-- > Foo.Baz.x   as    Qual Foo.Baz x
--
657 658 659 660 661
-- So we parse it from back to front
mkName str
  = split [] (reverse str)
  where
    split occ []        = Name (mkOccName occ) NameS
662 663 664 665 666 667 668 669 670
    split occ ('.':rev)	| not (null occ), 
			  not (null rev), head rev /= '.'
			= Name (mkOccName occ) (NameQ (mkModName (reverse rev)))
	-- The 'not (null occ)' guard ensures that
	-- 	mkName "&." = Name "&." NameS
	-- The 'rev' guards ensure that
	--	mkName ".&" = Name ".&" NameS
	--	mkName "Data.Bits..&" = Name ".&" (NameQ "Data.Bits")
	-- This rather bizarre case actually happened; (.&.) is in Data.Bits
671
    split occ (c:rev)   = split (c:occ) rev
672

aavogt's avatar
aavogt committed
673 674
-- | Only used internally
mkNameU :: String -> Uniq -> Name
675 676
mkNameU s (I# u) = Name (mkOccName s) (NameU u)

aavogt's avatar
aavogt committed
677 678
-- | Only used internally
mkNameL :: String -> Uniq -> Name
679 680
mkNameL s (I# u) = Name (mkOccName s) (NameL u)

aavogt's avatar
aavogt committed
681 682 683
-- | Used for 'x etc, but not available to the programmer
mkNameG :: NameSpace -> String -> String -> String -> Name
mkNameG ns pkg modu occ
Ian Lynagh's avatar
Ian Lynagh committed
684
  = Name (mkOccName occ) (NameG ns (mkPkgName pkg) (mkModName modu))
685

686
mkNameG_v, mkNameG_tc, mkNameG_d :: String -> String -> String -> Name
687 688 689 690 691 692 693 694 695 696 697 698 699 700 701
mkNameG_v  = mkNameG VarName
mkNameG_tc = mkNameG TcClsName
mkNameG_d  = mkNameG DataName

instance Eq Name where
  v1 == v2 = cmpEq (v1 `compare` v2)

instance Ord Name where
  (Name o1 f1) `compare` (Name o2 f2) = (f1 `compare` f2)   `thenCmp`
				        (o1 `compare` o2)

instance Eq NameFlavour where
  f1 == f2 = cmpEq (f1 `compare` f2)

instance Ord NameFlavour where
702
	-- NameS < NameQ < NameU < NameL < NameG
703
  NameS `compare` NameS = EQ
Ian Lynagh's avatar
Ian Lynagh committed
704
  NameS `compare` _     = LT
705

706 707
  (NameQ _)  `compare` NameS      = GT
  (NameQ m1) `compare` (NameQ m2) = m1 `compare` m2
Ian Lynagh's avatar
Ian Lynagh committed
708
  (NameQ _)  `compare` _          = LT
709 710 711

  (NameU _)  `compare` NameS      = GT
  (NameU _)  `compare` (NameQ _)  = GT
712 713 714
  (NameU u1) `compare` (NameU u2) | u1  <# u2 = LT
				  | u1 ==# u2 = EQ
				  | otherwise = GT
Ian Lynagh's avatar
Ian Lynagh committed
715
  (NameU _)  `compare` _     = LT
716

717 718 719 720 721 722
  (NameL _)  `compare` NameS      = GT
  (NameL _)  `compare` (NameQ _)  = GT
  (NameL _)  `compare` (NameU _)  = GT
  (NameL u1) `compare` (NameL u2) | u1  <# u2 = LT
				  | u1 ==# u2 = EQ
				  | otherwise = GT
Ian Lynagh's avatar
Ian Lynagh committed
723
  (NameL _)  `compare` _          = LT
724

725 726 727
  (NameG ns1 p1 m1) `compare` (NameG ns2 p2 m2) = (ns1 `compare` ns2) `thenCmp`
                                            (p1 `compare` p2) `thenCmp`
					    (m1 `compare` m2) 
Ian Lynagh's avatar
Ian Lynagh committed
728
  (NameG _ _ _)    `compare` _ = GT
729

Ian Lynagh's avatar
Ian Lynagh committed
730 731 732 733 734 735 736 737 738 739 740 741 742 743 744
data NameIs = Alone | Applied | Infix

showName :: Name -> String
showName = showName' Alone

showName' :: NameIs -> Name -> String
showName' ni nm
 = case ni of
       Alone        -> nms
       Applied
        | pnam      -> nms
        | otherwise -> "(" ++ nms ++ ")"
       Infix
        | pnam      -> "`" ++ nms ++ "`"
        | otherwise -> nms
745
    where
746 747 748 749 750
	-- For now, we make the NameQ and NameG print the same, even though
	-- NameQ is a qualified name (so what it means depends on what the
	-- current scope is), and NameG is an original name (so its meaning
	-- should be independent of what's in scope.
	-- We may well want to distinguish them in the end.
751 752
	-- Ditto NameU and NameL
        nms = case nm of
Ian Lynagh's avatar
Ian Lynagh committed
753 754 755 756 757
                    Name occ NameS         -> occString occ
                    Name occ (NameQ m)     -> modString m ++ "." ++ occString occ
                    Name occ (NameG _ _ m) -> modString m ++ "." ++ occString occ
                    Name occ (NameU u)     -> occString occ ++ "_" ++ show (I# u)
                    Name occ (NameL u)     -> occString occ ++ "_" ++ show (I# u)
758 759 760

        pnam = classify nms

Ian Lynagh's avatar
Ian Lynagh committed
761 762
        -- True if we are function style, e.g. f, [], (,)
        -- False if we are operator style, e.g. +, :+
763
        classify "" = False -- shouldn't happen; . operator is handled below
Ian Lynagh's avatar
Ian Lynagh committed
764
        classify (x:xs) | isAlpha x || (x `elem` "_[]()") =
765 766 767 768
                            case dropWhile (/='.') xs of
                                  (_:xs') -> classify xs'
                                  []      -> True
                        | otherwise = False
769

770
instance Show Name where
Ian Lynagh's avatar
Ian Lynagh committed
771
  show = showName
772

773
-- Tuple data and type constructors
774 775 776 777
-- | Tuple data constructor
tupleDataName :: Int -> Name
-- | Tuple type constructor
tupleTypeName :: Int -> Name
778

779
tupleDataName 0 = mk_tup_name 0 DataName
780
tupleDataName 1 = error "tupleDataName 1"
781
tupleDataName n = mk_tup_name (n-1) DataName
782

783
tupleTypeName 0 = mk_tup_name 0 TcClsName
784
tupleTypeName 1 = error "tupleTypeName 1"
785
tupleTypeName n = mk_tup_name (n-1) TcClsName
786

Ian Lynagh's avatar
Ian Lynagh committed
787
mk_tup_name :: Int -> NameSpace -> Name
788
mk_tup_name n_commas space
Ian Lynagh's avatar
Ian Lynagh committed
789
  = Name occ (NameG space (mkPkgName "ghc-prim") tup_mod)
790 791
  where
    occ = mkOccName ('(' : replicate n_commas ',' ++ ")")
Ian Lynagh's avatar
Ian Lynagh committed
792
    tup_mod = mkModName "GHC.Tuple"
793

794
-- Unboxed tuple data and type constructors
795 796 797 798
-- | Unboxed tuple data constructor
unboxedTupleDataName :: Int -> Name
-- | Unboxed tuple type constructor
unboxedTupleTypeName :: Int -> Name
799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814

unboxedTupleDataName 0 = error "unboxedTupleDataName 0"
unboxedTupleDataName 1 = error "unboxedTupleDataName 1"
unboxedTupleDataName n = mk_unboxed_tup_name (n-1) DataName

unboxedTupleTypeName 0 = error "unboxedTupleTypeName 0"
unboxedTupleTypeName 1 = error "unboxedTupleTypeName 1"
unboxedTupleTypeName n = mk_unboxed_tup_name (n-1) TcClsName

mk_unboxed_tup_name :: Int -> NameSpace -> Name
mk_unboxed_tup_name n_commas space
  = Name occ (NameG space (mkPkgName "ghc-prim") tup_mod)
  where
    occ = mkOccName ("(#" ++ replicate n_commas ',' ++ "#)")
    tup_mod = mkModName "GHC.Tuple"

815

816

817 818 819 820 821 822 823 824 825 826 827
-----------------------------------------------------
--		Locations
-----------------------------------------------------

data Loc
  = Loc { loc_filename :: String
	, loc_package  :: String
	, loc_module   :: String
	, loc_start    :: CharPos
	, loc_end      :: CharPos }

828
type CharPos = (Int, Int)	-- ^ Line and character position
829

830

831 832 833 834 835 836
-----------------------------------------------------
--
--	The Info returned by reification
--
-----------------------------------------------------

aavogt's avatar
aavogt committed
837 838
-- | Obtained from 'reify' in the 'Q' Monad.
data Info
839 840 841 842 843 844 845
  = 
  -- | A class, with a list of its visible instances
  ClassI 
      Dec
      [InstanceDec]
  
  -- | A class method
846
  | ClassOpI
847 848 849 850 851 852
       Name
       Type
       ParentName
       Fixity
  
  -- | A \"plain\" type constructor. \"Fancier\" type constructors are returned using 'PrimTyConI' or 'FamilyI' as appropriate
853 854 855
  | TyConI 
        Dec

856 857
  -- | A type or data family, with a list of its visible instances
  | FamilyI 
858 859
        Dec
        [InstanceDec]
860 861 862 863 864 865 866 867
  
  -- | A \"primitive\" type constructor, which can't be expressed with a 'Dec'. Examples: @(->)@, @Int#@.
  | PrimTyConI 
       Name
       Arity
       Unlifted
  
  -- | A data constructor
868
  | DataConI 
869 870 871 872
       Name
       Type
       ParentName
       Fixity
873

874 875 876 877 878 879 880 881 882 883
  {- | 
  A \"value\" variable (as opposed to a type variable, see 'TyVarI').
  
  The @Maybe Dec@ field contains @Just@ the declaration which 
  defined the variable -- including the RHS of the declaration -- 
  or else @Nothing@, in the case where the RHS is unavailable to
  the compiler. At present, this value is _always_ @Nothing@:
  returning the RHS has not yet been implemented because of
  lack of interest.
  -}
884
  | VarI 
885 886 887 888
       Name
       Type
       (Maybe Dec)
       Fixity
889

890 891 892 893 894 895 896
  {- | 
  A type variable.
  
  The @Type@ field contains the type which underlies the variable.
  At present, this is always @'VarT' theName@, but future changes
  may permit refinement of this.
  -}
897 898 899
  | TyVarI 	-- Scoped type variable
	Name
	Type	-- What it is bound to
900
  deriving( Show, Data, Typeable )
901

902 903 904 905 906 907 908 909 910 911 912 913
{- | 
In 'ClassOpI' and 'DataConI', name of the parent class or type
-}
type ParentName = Name

-- | In 'PrimTyConI', arity of the type constructor
type Arity = Int

-- | In 'PrimTyConI', is the type constructor unlifted?
type Unlifted = Bool

-- | 'InstanceDec' desribes a single instance of a class or type function.
914
-- It is just a 'Dec', but guaranteed to be one of the following:
915 916 917 918 919 920
--
--   * 'InstanceD' (with empty @['Dec']@)
--
--   * 'DataInstD' or 'NewtypeInstD' (with empty derived @['Name']@)
--
--   * 'TySynInstD'
921
type InstanceDec = Dec
922

923 924 925 926
data Fixity          = Fixity Int FixityDirection
    deriving( Eq, Show, Data, Typeable )
data FixityDirection = InfixL | InfixR | InfixN
    deriving( Eq, Show, Data, Typeable )
927

928
-- | Highest allowed operator precedence for 'Fixity' constructor (answer: 9)
929
maxPrecedence :: Int
930
maxPrecedence = (9::Int)
931

932
-- | Default fixity: @infixl 9@
933
defaultFixity :: Fixity
934 935 936
defaultFixity = Fixity maxPrecedence InfixL


937
{-
938 939
Note [Unresolved infix]
~~~~~~~~~~~~~~~~~~~~~~~
940 941
-}
{- $infix #infix#
942 943 944
When implementing antiquotation for quasiquoters, one often wants
to parse strings into expressions:

945
> parse :: String -> Maybe Exp
946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999

But how should we parse @a + b * c@? If we don't know the fixities of
@+@ and @*@, we don't know whether to parse it as @a + (b * c)@ or @(a
+ b) * c@.

In cases like this, use 'UInfixE' or 'UInfixP', which stand for
\"unresolved infix expression\" and \"unresolved infix pattern\". When
the compiler is given a splice containing a tree of @UInfixE@
applications such as

> UInfixE
>   (UInfixE e1 op1 e2)
>   op2
>   (UInfixE e3 op3 e4)

it will look up and the fixities of the relevant operators and
reassociate the tree as necessary.

  * trees will not be reassociated across 'ParensE' or 'ParensP',
    which are of use for parsing expressions like

    > (a + b * c) + d * e

  * 'InfixE' and 'InfixP' expressions are never reassociated.

  * The 'UInfixE' constructor doesn't support sections. Sections
    such as @(a *)@ have no ambiguity, so 'InfixE' suffices. For longer
    sections such as @(a + b * c -)@, use an 'InfixE' constructor for the
    outer-most section, and use 'UInfixE' constructors for all
    other operators:

    > InfixE
    >   Just (UInfixE ...a + b * c...)
    >   op
    >   Nothing

    Sections such as @(a + b +)@ and @((a + b) +)@ should be rendered
    into 'Exp's differently:

    > (+ a + b)   ---> InfixE Nothing + (Just $ UInfixE a + b)
    >                    -- will result in a fixity error if (+) is left-infix
    > (+ (a + b)) ---> InfixE Nothing + (Just $ ParensE $ UInfixE a + b)
    >                    -- no fixity errors

  * Quoted expressions such as

    > [| a * b + c |] :: Q Exp
    > [p| a : b : c |] :: Q Pat

    will never contain 'UInfixE', 'UInfixP', 'ParensE', or 'ParensP'
    constructors.

-}

1000 1001 1002 1003 1004 1005
-----------------------------------------------------
--
--	The main syntax data types
--
-----------------------------------------------------

1006 1007
data Lit = CharL Char 
         | StringL String 
aavogt's avatar
aavogt committed
1008
         | IntegerL Integer     -- ^ Used for overloaded and non-overloaded
1009 1010 1011 1012 1013
                                -- literals. We don't have a good way to
                                -- represent non-overloaded literals at
                                -- the moment. Maybe that doesn't matter?
         | RationalL Rational   -- Ditto
         | IntPrimL Integer
1014
         | WordPrimL Integer
1015 1016
         | FloatPrimL Rational
         | DoublePrimL Rational
reinerp's avatar
reinerp committed
1017
         | StringPrimL [Word8]	-- ^ A primitive C-style string, type Addr#
1018
    deriving( Show, Eq, Data, Typeable )
1019 1020 1021 1022 1023

    -- We could add Int, Float, Double etc, as we do in HsLit, 
    -- but that could complicate the
    -- suppposedly-simple TH.Syntax literal type

aavogt's avatar
aavogt committed
1024
-- | Pattern in Haskell given in @{}@
1025
data Pat 
aavogt's avatar
aavogt committed
1026 1027 1028
  = LitP Lit                      -- ^ @{ 5 or 'c' }@
  | VarP Name                     -- ^ @{ x }@
  | TupP [Pat]                    -- ^ @{ (p1,p2) }@
1029
  | UnboxedTupP [Pat]             -- ^ @{ (# p1,p2 #) }@
aavogt's avatar
aavogt committed
1030 1031
  | ConP Name [Pat]               -- ^ @data T1 = C1 t1 t2; {C1 p1 p1} = e@
  | InfixP Pat Name Pat           -- ^ @foo ({x :+ y}) = e@
1032 1033
  | UInfixP Pat Name Pat          -- ^ @foo ({x :+ y}) = e@
                                  --
1034
                                  -- See "Language.Haskell.TH.Syntax#infix"
1035 1036
  | ParensP Pat                   -- ^ @{(p)}@
                                  --
1037
                                  -- See "Language.Haskell.TH.Syntax#infix"
aavogt's avatar
aavogt committed
1038 1039 1040 1041 1042 1043 1044
  | TildeP Pat                    -- ^ @{ ~p }@
  | BangP Pat                     -- ^ @{ !p }@
  | AsP Name Pat                  -- ^ @{ x \@ p }@
  | WildP                         -- ^ @{ _ }@
  | RecP Name [FieldPat]          -- ^ @f (Pt { pointx = x }) = g x@
  | ListP [ Pat ]                 -- ^ @{ [1,2,3] }@
  | SigP Pat Type                 -- ^ @{ p :: t }@
reinerp's avatar
reinerp committed
1045
  | ViewP Exp Pat                 -- ^ @{ e -> p }@
1046
  deriving( Show, Eq, Data, Typeable )
1047 1048 1049

type FieldPat = (Name,Pat)

aavogt's avatar
aavogt committed
1050
data Match = Match Pat Body [Dec] -- ^ @case e of { pat -> body where decs }@
1051
    deriving( Show, Eq, Data, Typeable )
1052
data Clause = Clause [Pat] Body [Dec]
aavogt's avatar
aavogt committed
1053
                                  -- ^ @f { p1 p2 = body where decs }@
1054
    deriving( Show, Eq, Data, Typeable )
1055 1056
 
data Exp 
aavogt's avatar
aavogt committed
1057 1058 1059 1060
  = VarE Name                          -- ^ @{ x }@
  | ConE Name                          -- ^ @data T1 = C1 t1 t2; p = {C1} e1 e2  @
  | LitE Lit                           -- ^ @{ 5 or 'c'}@
  | AppE Exp Exp                       -- ^ @{ f x }@
1061

aavogt's avatar
aavogt committed
1062
  | InfixE (Maybe Exp) Exp (Maybe Exp) -- ^ @{x + y} or {(x+)} or {(+ x)} or {(+)}@
1063

1064 1065 1066 1067 1068 1069
    -- It's a bit gruesome to use an Exp as the
    -- operator, but how else can we distinguish
    -- constructors from non-constructors?
    -- Maybe there should be a var-or-con type?
    -- Or maybe we should leave it to the String itself?

1070 1071
  | UInfixE Exp Exp Exp                -- ^ @{x + y}@
                                       --
1072
                                       -- See "Language.Haskell.TH.Syntax#infix"
1073 1074
  | ParensE Exp                        -- ^ @{ (e) }@
                                       --
1075
                                       -- See "Language.Haskell.TH.Syntax#infix"
aavogt's avatar
aavogt committed
1076
  | LamE [Pat] Exp                     -- ^ @{ \ p1 p2 -> e }@
1077
  | LamCaseE [Match]                   -- ^ @{ \case m1; m2 }@
aavogt's avatar
aavogt committed
1078
  | TupE [Exp]                         -- ^ @{ (e1,e2) }  @
1079
  | UnboxedTupE [Exp]                  -- ^ @{ (# e1,e2 #) }  @
aavogt's avatar
aavogt committed
1080
  | CondE Exp Exp Exp                  -- ^ @{ if e1 then e2 else e3 }@
1081
  | MultiIfE [(Guard, Exp)]            -- ^ @{ if | g1 -> e1 | g2 -> e2 }@
aavogt's avatar
aavogt committed
1082 1083 1084
  | LetE [Dec] Exp                     -- ^ @{ let x=e1;   y=e2 in e3 }@
  | CaseE Exp [Match]                  -- ^ @{ case e of m1; m2 }@
  | DoE [Stmt]                         -- ^ @{ do { p <- e1; e2 }  }@
1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095
  | CompE [Stmt]                       -- ^ @{ [ (x,y) | x <- xs, y <- ys ] }@ 
      --
      -- The result expression of the comprehension is
      -- the /last/ of the @'Stmt'@s, and should be a 'NoBindS'.
      --
      -- E.g. translation:
      --
      -- > [ f x | x <- xs ]
      --
      -- > CompE [BindS (VarP x) (VarE xs), NoBindS (AppE (VarE f) (VarE x))]

aavogt's avatar
aavogt committed
1096 1097 1098 1099 1100
  | ArithSeqE Range                    -- ^ @{ [ 1 ,2 .. 10 ] }@
  | ListE [ Exp ]                      -- ^ @{ [1,2,3] }@
  | SigE Exp Type                      -- ^ @{ e :: t }@
  | RecConE Name [FieldExp]            -- ^ @{ T { x = y, z = w } }@
  | RecUpdE Exp [FieldExp]             -- ^ @{ (f x) { z = w } }@
1101
  deriving( Show, Eq, Data, Typeable )
1102 1103 1104 1105 1106 1107

type FieldExp = (Name,Exp)

-- Omitted: implicit parameters

data Body
1108 1109 1110
  = GuardedB [(Guard,Exp)]   -- ^ @f p { | e1 = e2 
                                 --      | e3 = e4 } 
                                 -- where ds@
aavogt's avatar
aavogt committed
1111
  | NormalB Exp              -- ^ @f p { = e } where ds@
1112
  deriving( Show, Eq, Data, Typeable )
1113

1114
data Guard
1115 1116
  = NormalG Exp -- ^ @f x { | odd x } = x@
  | PatG [Stmt] -- ^ @f x { | Just y <- x, Just z <- y } = z@
1117
  deriving( Show, Eq, Data, Typeable )
1118

1119 1120 1121 1122 1123
data Stmt
  = BindS Pat Exp
  | LetS [ Dec ]
  | NoBindS Exp
  | ParS [[Stmt]]
1124
  deriving( Show, Eq, Data, Typeable )
1125 1126 1127

data Range = FromR Exp | FromThenR Exp Exp
           | FromToR Exp Exp | FromThenToR Exp Exp Exp
1128
          deriving( Show, Eq, Data, Typeable )
1129 1130
  
data Dec 
aavogt's avatar
aavogt committed
1131 1132
  = FunD Name [Clause]            -- ^ @{ f p1 p2 = b where decs }@
  | ValD Pat Body [Dec]           -- ^ @{ p = b where decs }@
1133
  | DataD Cxt Name [TyVarBndr] 
aavogt's avatar
aavogt committed
1134 1135
         [Con] [Name]             -- ^ @{ data Cxt x => T x = A x | B (T x)
                                  --       deriving (Z,W)}@
1136
  | NewtypeD Cxt Name [TyVarBndr] 
aavogt's avatar
aavogt committed
1137 1138 1139
         Con [Name]               -- ^ @{ newtype Cxt x => T x = A (B x)
                                  --       deriving (Z,W)}@
  | TySynD Name [TyVarBndr] Type  -- ^ @{ type T x = (x,x) }@
1140
  | ClassD Cxt Name [TyVarBndr] 
aavogt's avatar
aavogt committed
1141 1142 1143 1144
         [FunDep] [Dec]           -- ^ @{ class Eq a => Ord a where ds }@
  | InstanceD Cxt Type [Dec]      -- ^ @{ instance Show w => Show [w]
                                  --       where ds }@
  | SigD Name Type                -- ^ @{ length :: [a] -> Int }@
1145 1146
  | ForeignD Foreign              -- ^ @{ foreign import ... }
                                  --{ foreign export ... }@
aavogt's avatar
aavogt committed
1147

1148 1149
  | InfixD Fixity Name            -- ^ @{ infix 3 foo }@

aavogt's avatar
aavogt committed
1150
  -- | pragmas
1151
  | PragmaD Pragma                -- ^ @{ {\-# INLINE [1] foo #-\} }@
aavogt's avatar
aavogt committed
1152