ghc-9.14.1: GHC/Hs/Binds.hs
{-# LANGUAGE AllowAmbiguousTypes #-} -- used to pass the phase to ppr_mult_ann since MultAnn is a type family
{-# LANGUAGE CPP #-}
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE UndecidableInstances #-} -- Wrinkle in Note [Trees That Grow]
-- in module Language.Haskell.Syntax.Extension
{-# OPTIONS_GHC -Wno-orphans #-} -- Outputable
{-
(c) The University of Glasgow 2006
(c) The GRASP/AQUA Project, Glasgow University, 1992-1998
\section[HsBinds]{Abstract syntax: top-level bindings and signatures}
Datatype for: @BindGroup@, @Bind@, @Sig@, @Bind@.
-}
module GHC.Hs.Binds
( module Language.Haskell.Syntax.Binds
, module GHC.Hs.Binds
, HsRuleBndrsAnn(..)
) where
import GHC.Prelude
import Language.Haskell.Syntax.Extension
import Language.Haskell.Syntax.Binds
import Language.Haskell.Syntax.Expr( LHsExpr )
import {-# SOURCE #-} GHC.Hs.Expr ( pprExpr, pprLExpr, pprFunBind, pprPatBind )
import {-# SOURCE #-} GHC.Hs.Pat (pprLPat )
import GHC.Data.BooleanFormula ( LBooleanFormula, pprBooleanFormulaNormal )
import GHC.Types.Tickish
import GHC.Hs.Extension
import GHC.Parser.Annotation
import GHC.Hs.Type
import GHC.Tc.Types.Evidence
import GHC.Core.Type
import GHC.Types.Name.Set
import GHC.Types.Basic
import GHC.Types.SourceText
import GHC.Types.SrcLoc as SrcLoc
import GHC.Types.Var
import GHC.Types.Name
import GHC.Utils.Outputable
import GHC.Utils.Panic
import GHC.Utils.Misc ((<||>))
import Data.Function
import Data.List (sortBy)
import Data.Data (Data)
{-
************************************************************************
* *
\subsection{Bindings: @BindGroup@}
* *
************************************************************************
Global bindings (where clauses)
-}
-- the ...LR datatypes are parameterized by two id types,
-- one for the left and one for the right.
type instance XHsValBinds (GhcPass pL) (GhcPass pR) = EpAnn (AnnList (EpToken "where"))
type instance XHsIPBinds (GhcPass pL) (GhcPass pR) = EpAnn (AnnList (EpToken "where"))
type instance XEmptyLocalBinds (GhcPass pL) (GhcPass pR) = NoExtField
type instance XXHsLocalBindsLR (GhcPass pL) (GhcPass pR) = DataConCantHappen
-- ---------------------------------------------------------------------
-- Deal with ValBindsOut
-- TODO: make this the only type for ValBinds
data NHsValBindsLR idL
= NValBinds
[(RecFlag, LHsBinds idL)]
[LSig GhcRn]
type instance XValBinds (GhcPass pL) (GhcPass pR) = AnnSortKey BindTag
type instance XXValBindsLR (GhcPass pL) pR
= NHsValBindsLR (GhcPass pL)
-- ---------------------------------------------------------------------
type instance XFunBind (GhcPass pL) GhcPs = NoExtField
type instance XFunBind (GhcPass pL) GhcRn = NameSet
-- ^ After the renamer (but before the type-checker), the FunBind
-- extension field contains the locally-bound free variables of this
-- defn. See Note [Bind free vars]
type instance XFunBind (GhcPass pL) GhcTc = (HsWrapper, [CoreTickish])
-- ^ After the type-checker, the FunBind extension field contains
-- the ticks to put on the rhs, if any, and a coercion from the
-- type of the MatchGroup to the type of the Id.
-- Example:
--
-- @
-- f :: Int -> forall a. a -> a
-- f x y = y
-- @
--
-- Then the MatchGroup will have type (Int -> a' -> a')
-- (with a free type variable a'). The coercion will take
-- a CoreExpr of this type and convert it to a CoreExpr of
-- type Int -> forall a'. a' -> a'
-- Notice that the coercion captures the free a'.
type instance XPatBind GhcPs (GhcPass pR) = NoExtField
type instance XPatBind GhcRn (GhcPass pR) = NameSet -- See Note [Bind free vars]
type instance XPatBind GhcTc (GhcPass pR) =
( Type -- Type of the GRHSs
, ( [CoreTickish] -- Ticks to put on the rhs, if any
, [[CoreTickish]] ) ) -- and ticks to put on the bound variables.
type instance XVarBind (GhcPass pL) (GhcPass pR) = XVarBindGhc pL pR
type family XVarBindGhc pL pR where
XVarBindGhc 'Typechecked 'Typechecked = NoExtField
XVarBindGhc _ _ = DataConCantHappen
type instance XPatSynBind (GhcPass pL) (GhcPass pR) = NoExtField
type instance XXHsBindsLR GhcPs pR = DataConCantHappen
type instance XXHsBindsLR GhcRn pR = DataConCantHappen
type instance XXHsBindsLR GhcTc pR = AbsBinds
type instance XPSB (GhcPass idL) GhcPs = AnnPSB
type instance XPSB (GhcPass idL) GhcRn = NameSet -- Post renaming, FVs. See Note [Bind free vars]
type instance XPSB (GhcPass idL) GhcTc = NameSet
type instance XXPatSynBind (GhcPass idL) (GhcPass idR) = DataConCantHappen
data AnnPSB
= AnnPSB {
ap_pattern :: EpToken "pattern",
ap_openc :: Maybe (EpToken "{"),
ap_closec :: Maybe (EpToken "}"),
ap_larrow :: Maybe (EpUniToken "<-" "←"),
ap_equal :: Maybe (EpToken "=")
} deriving Data
instance NoAnn AnnPSB where
noAnn = AnnPSB noAnn noAnn noAnn noAnn noAnn
setTcMultAnn :: Mult -> HsMultAnn GhcRn -> HsMultAnn GhcTc
setTcMultAnn mult (HsLinearAnn _) = HsLinearAnn mult
setTcMultAnn mult (HsExplicitMult _ p) = HsExplicitMult mult p
setTcMultAnn mult (HsUnannotated _) = HsUnannotated mult
getTcMultAnn :: HsMultAnn GhcTc -> Mult
getTcMultAnn (HsLinearAnn mult) = mult
getTcMultAnn (HsExplicitMult mult _) = mult
getTcMultAnn (HsUnannotated mult) = mult
-- ---------------------------------------------------------------------
-- | Typechecked, generalised bindings, used in the output to the type checker.
-- See Note [AbsBinds].
data AbsBinds = AbsBinds {
abs_tvs :: [TyVar],
abs_ev_vars :: [EvVar], -- ^ Includes equality constraints
-- | AbsBinds only gets used when idL = idR after renaming,
-- but these need to be idL's for the collect... code in HsUtil
-- to have the right type
abs_exports :: [ABExport],
-- | Evidence bindings
-- Why a list? See "GHC.Tc.TyCl.Instance"
-- Note [Typechecking plan for instance declarations]
abs_ev_binds :: [TcEvBinds],
-- | Typechecked user bindings
abs_binds :: LHsBinds GhcTc,
abs_sig :: Bool -- See Note [The abs_sig field of AbsBinds]
}
-- Consider (AbsBinds tvs ds [(ftvs, poly_f, mono_f) binds]
--
-- Creates bindings for (polymorphic, overloaded) poly_f
-- in terms of monomorphic, non-overloaded mono_f
--
-- Invariants:
-- 1. 'binds' binds mono_f
-- 2. ftvs is a subset of tvs
-- 3. ftvs includes all tyvars free in ds
--
-- See Note [AbsBinds]
-- | Abstraction Bindings Export
data ABExport
= ABE { abe_poly :: Id -- ^ Any INLINE pragma is attached to this Id
, abe_mono :: Id
, abe_wrap :: HsWrapper -- ^ See Note [ABExport wrapper]
-- Shape: (forall abs_tvs. abs_ev_vars => abe_mono) ~ abe_poly
, abe_prags :: TcSpecPrags -- ^ SPECIALISE pragmas
}
{-
Note [AbsBinds]
~~~~~~~~~~~~~~~
The AbsBinds constructor is used in the output of the type checker, to
record *typechecked* and *generalised* bindings. Specifically
AbsBinds { abs_tvs = tvs
, abs_ev_vars = [d1,d2]
, abs_exports = [ABE { abe_poly = fp, abe_mono = fm
, abe_wrap = fwrap }
ABE { slly for g } ]
, abs_ev_binds = DBINDS
, abs_binds = BIND[fm,gm] }
where 'BIND' binds the monomorphic Ids 'fm' and 'gm', means
fp = fwrap [/\ tvs. \d1 d2. letrec { DBINDS ]
[ ; BIND[fm,gm] } ]
[ in fm ]
gp = ...same again, with gm instead of fm
The 'fwrap' is an impedance-matcher that typically does nothing; see
Note [ABExport wrapper].
This is a pretty bad translation, because it duplicates all the bindings.
So the desugarer tries to do a better job:
fp = /\ [a,b] -> \ [d1,d2] -> case tp [a,b] [d1,d2] of
(fm,gm) -> fm
..ditto for gp..
tp = /\ [a,b] -> \ [d1,d2] -> letrec { DBINDS; BIND }
in (fm,gm)
In general:
* abs_tvs are the type variables over which the binding group is
generalised
* abs_ev_var are the evidence variables (usually dictionaries)
over which the binding group is generalised
* abs_binds are the monomorphic bindings
* abs_ex_binds are the evidence bindings that wrap the abs_binds
* abs_exports connects the monomorphic Ids bound by abs_binds
with the polymorphic Ids bound by the AbsBinds itself.
For example, consider a module M, with this top-level binding, where
there is no type signature for M.reverse,
M.reverse [] = []
M.reverse (x:xs) = M.reverse xs ++ [x]
In Hindley-Milner, a recursive binding is typechecked with the
*recursive* uses being *monomorphic*. So after typechecking *and*
desugaring we will get something like this
M.reverse :: forall a. [a] -> [a]
= /\a. letrec
reverse :: [a] -> [a] = \xs -> case xs of
[] -> []
(x:xs) -> reverse xs ++ [x]
in reverse
Notice that 'M.reverse' is polymorphic as expected, but there is a local
definition for plain 'reverse' which is *monomorphic*. The type variable
'a' scopes over the entire letrec.
That's after desugaring. What about after type checking but before
desugaring? That's where AbsBinds comes in. It looks like this:
AbsBinds { abs_tvs = [a]
, abs_ev_vars = []
, abs_exports = [ABE { abe_poly = M.reverse :: forall a. [a] -> [a],
, abe_mono = reverse :: [a] -> [a]}]
, abs_ev_binds = {}
, abs_binds = { reverse :: [a] -> [a]
= \xs -> case xs of
[] -> []
(x:xs) -> reverse xs ++ [x] } }
Here,
* abs_tvs says what type variables are abstracted over the binding
group, just 'a' in this case.
* abs_binds is the *monomorphic* bindings of the group
* abs_exports describes how to get the polymorphic Id 'M.reverse'
from the monomorphic one 'reverse'
Notice that the *original* function (the polymorphic one you thought
you were defining) appears in the abe_poly field of the
abs_exports. The bindings in abs_binds are for fresh, local, Ids with
a *monomorphic* Id.
If there is a group of mutually recursive (see Note [Polymorphic
recursion]) functions without type signatures, we get one AbsBinds
with the monomorphic versions of the bindings in abs_binds, and one
element of abe_exports for each variable bound in the mutually
recursive group. This is true even for pattern bindings. Example:
(f,g) = (\x -> x, f)
After type checking we get
AbsBinds { abs_tvs = [a]
, abs_exports = [ ABE { abe_poly = M.f :: forall a. a -> a
, abe_mono = f :: a -> a }
, ABE { abe_poly = M.g :: forall a. a -> a
, abe_mono = g :: a -> a }]
, abs_binds = { (f,g) = (\x -> x, f) }
Note [Polymorphic recursion]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Consider
Rec { f x = ...(g ef)...
; g :: forall a. [a] -> [a]
; g y = ...(f eg)... }
These bindings /are/ mutually recursive (f calls g, and g calls f).
But we can use the type signature for g to break the recursion,
like this:
1. Add g :: forall a. [a] -> [a] to the type environment
2. Typecheck the definition of f, all by itself,
including generalising it to find its most general
type, say f :: forall b. b -> b -> [b]
3. Extend the type environment with that type for f
4. Typecheck the definition of g, all by itself,
checking that it has the type claimed by its signature
Steps 2 and 4 each generate a separate AbsBinds, so we end
up with
Rec { AbsBinds { ...for f ... }
; AbsBinds { ...for g ... } }
This approach allows both f and to call each other
polymorphically, even though only g has a signature.
We get an AbsBinds that encompasses multiple source-program
bindings only when
* Each binding in the group has at least one binder that
lacks a user type signature
* The group forms a strongly connected component
Note [The abs_sig field of AbsBinds]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
The abs_sig field supports a couple of special cases for bindings.
Consider
x :: Num a => (# a, a #)
x = (# 3, 4 #)
The general desugaring for AbsBinds would give
x = /\a. \ ($dNum :: Num a) ->
letrec xm = (# fromInteger $dNum 3, fromInteger $dNum 4 #) in
xm
But that has an illegal let-binding for an unboxed tuple. In this
case we'd prefer to generate the (more direct)
x = /\ a. \ ($dNum :: Num a) ->
(# fromInteger $dNum 3, fromInteger $dNum 4 #)
A similar thing happens with representation-polymorphic defns
(#11405):
undef :: forall (r :: RuntimeRep) (a :: TYPE r). HasCallStack => a
undef = error "undef"
Again, the vanilla desugaring gives a local let-binding for a
representation-polymorphic (undefm :: a), which is illegal. But
again we can desugar without a let:
undef = /\ a. \ (d:HasCallStack) -> error a d "undef"
The abs_sig field supports this direct desugaring, with no local
let-binding. When abs_sig = True
* the abs_binds is single FunBind
* the abs_exports is a singleton
* we have a complete type sig for binder
and hence the abs_binds is non-recursive
(it binds the mono_id but refers to the poly_id
These properties are exploited in GHC.HsToCore.Binds.dsAbsBinds to
generate code without a let-binding.
Note [ABExport wrapper]
~~~~~~~~~~~~~~~~~~~~~~~
Consider
(f,g) = (\x.x, \y.y)
This ultimately desugars to something like this:
tup :: forall a b. (a->a, b->b)
tup = /\a b. (\x:a.x, \y:b.y)
f :: forall a. a -> a
f = /\a. case tup a Any of
(fm::a->a,gm:Any->Any) -> fm
...similarly for g...
The abe_wrap field deals with impedance-matching between
(/\a b. case tup a b of { (f,g) -> f })
and the thing we really want, which may have fewer type
variables. The action happens in GHC.Tc.Gen.Bind.mkExport.
Note [Bind free vars]
~~~~~~~~~~~~~~~~~~~~~
The extension fields of FunBind, PatBind and PatSynBind at GhcRn records the free
variables of the definition. It is used for the following purposes:
a) Dependency analysis prior to type checking
(see GHC.Tc.Gen.Bind.tc_group)
b) Deciding whether we can do generalisation of the binding
(see GHC.Tc.Gen.Bind.decideGeneralisationPlan)
c) Deciding whether the binding can be used in static forms
(see GHC.Tc.Gen.Expr.checkClosedInStaticForm for the HsStatic case and
GHC.Tc.Gen.Bind.isClosedBndrGroup).
Specifically,
* it includes all free vars that are defined in this module
(including top-level things and lexically scoped type variables)
* it excludes imported vars; this is just to keep the set smaller
* Before renaming, and after typechecking, the field is unused;
it's just an error thunk
-}
instance (OutputableBndrId pl, OutputableBndrId pr)
=> Outputable (HsLocalBindsLR (GhcPass pl) (GhcPass pr)) where
ppr (HsValBinds _ bs) = ppr bs
ppr (HsIPBinds _ bs) = ppr bs
ppr (EmptyLocalBinds _) = empty
instance (OutputableBndrId pl, OutputableBndrId pr)
=> Outputable (HsValBindsLR (GhcPass pl) (GhcPass pr)) where
ppr (ValBinds _ binds sigs)
= pprDeclList (pprLHsBindsForUser binds sigs)
ppr (XValBindsLR (NValBinds sccs sigs))
= getPprDebug $ \case
-- Print with sccs showing
True -> vcat (map ppr sigs) $$ vcat (map ppr_scc sccs)
False -> pprDeclList (pprLHsBindsForUser (concat (map snd sccs)) sigs)
where
ppr_scc (rec_flag, binds) = pp_rec rec_flag <+> pprLHsBinds binds
pp_rec Recursive = text "rec"
pp_rec NonRecursive = text "nonrec"
pprLHsBinds :: (OutputableBndrId idL, OutputableBndrId idR)
=> LHsBindsLR (GhcPass idL) (GhcPass idR) -> SDoc
pprLHsBinds binds
| isEmptyLHsBinds binds = empty
| otherwise = pprDeclList (map ppr binds)
pprLHsBindsForUser :: (OutputableBndrId idL,
OutputableBndrId idR,
OutputableBndrId id2)
=> LHsBindsLR (GhcPass idL) (GhcPass idR) -> [LSig (GhcPass id2)] -> [SDoc]
-- pprLHsBindsForUser is different to pprLHsBinds because
-- a) No braces: 'let' and 'where' include a list of HsBindGroups
-- and we don't want several groups of bindings each
-- with braces around
-- b) Sort by location before printing
-- c) Include signatures
pprLHsBindsForUser binds sigs
= map snd (sort_by_loc decls)
where
decls :: [(SrcSpan, SDoc)]
decls = [(locA loc, ppr sig) | L loc sig <- sigs] ++
[(locA loc, ppr bind) | L loc bind <- binds]
sort_by_loc decls = sortBy (SrcLoc.leftmost_smallest `on` fst) decls
pprDeclList :: [SDoc] -> SDoc -- Braces with a space
-- Print a bunch of declarations
-- One could choose { d1; d2; ... }, using 'sep'
-- or d1
-- d2
-- ..
-- using vcat
-- At the moment we chose the latter
-- Also we do the 'pprDeeperList' thing.
pprDeclList ds = pprDeeperList vcat ds
------------
emptyLocalBinds :: HsLocalBindsLR (GhcPass a) (GhcPass b)
emptyLocalBinds = EmptyLocalBinds noExtField
eqEmptyLocalBinds :: HsLocalBindsLR a b -> Bool
eqEmptyLocalBinds (EmptyLocalBinds _) = True
eqEmptyLocalBinds _ = False
isEmptyValBinds :: HsValBindsLR (GhcPass a) (GhcPass b) -> Bool
isEmptyValBinds (ValBinds _ ds sigs) = isEmptyLHsBinds ds && null sigs
isEmptyValBinds (XValBindsLR (NValBinds ds sigs)) = null ds && null sigs
emptyValBindsIn, emptyValBindsOut :: HsValBindsLR (GhcPass a) (GhcPass b)
emptyValBindsIn = ValBinds NoAnnSortKey [] []
emptyValBindsOut = XValBindsLR (NValBinds [] [])
emptyLHsBinds :: LHsBindsLR (GhcPass idL) idR
emptyLHsBinds = []
isEmptyLHsBinds :: LHsBindsLR (GhcPass idL) idR -> Bool
isEmptyLHsBinds = null
------------
plusHsValBinds :: HsValBinds (GhcPass a) -> HsValBinds (GhcPass a)
-> HsValBinds(GhcPass a)
plusHsValBinds (ValBinds _ ds1 sigs1) (ValBinds _ ds2 sigs2)
= ValBinds NoAnnSortKey (ds1 ++ ds2) (sigs1 ++ sigs2)
plusHsValBinds (XValBindsLR (NValBinds ds1 sigs1))
(XValBindsLR (NValBinds ds2 sigs2))
= XValBindsLR (NValBinds (ds1 ++ ds2) (sigs1 ++ sigs2))
plusHsValBinds _ _
= panic "HsBinds.plusHsValBinds"
instance (OutputableBndrId pl, OutputableBndrId pr)
=> Outputable (HsBindLR (GhcPass pl) (GhcPass pr)) where
ppr mbind = ppr_monobind mbind
ppr_monobind :: forall idL idR.
(OutputableBndrId idL, OutputableBndrId idR)
=> HsBindLR (GhcPass idL) (GhcPass idR) -> SDoc
ppr_monobind (PatBind { pat_lhs = pat, pat_mult = mult_ann, pat_rhs = grhss })
= pprHsMultAnn @idL mult_ann
<+> pprPatBind pat grhss
ppr_monobind (VarBind { var_id = var, var_rhs = rhs })
= sep [pprBndr CasePatBind var, nest 2 $ equals <+> pprExpr (unLoc rhs)]
ppr_monobind (FunBind { fun_id = fun,
fun_matches = matches,
fun_ext = ext })
= pprTicks empty ticksDoc
$$ whenPprDebug (pprBndr LetBind (unLoc fun))
$$ pprFunBind matches
$$ whenPprDebug (pprIfTc @idR $ wrapDoc)
where
ticksDoc :: SDoc
ticksDoc = case ghcPass @idR of
GhcPs -> empty
GhcRn -> empty
GhcTc | (_, ticks) <- ext ->
if null ticks
then empty
else text "-- ticks = " <> ppr ticks
wrapDoc :: SDoc
wrapDoc = case ghcPass @idR of
GhcPs -> empty
GhcRn -> empty
GhcTc | (wrap, _) <- ext -> ppr wrap
ppr_monobind (PatSynBind _ psb) = ppr psb
ppr_monobind (XHsBindsLR b) = case ghcPass @idL of
GhcTc -> ppr_absbinds b
where
ppr_absbinds (AbsBinds { abs_tvs = tyvars, abs_ev_vars = dictvars
, abs_exports = exports, abs_binds = val_binds
, abs_ev_binds = ev_binds })
= sdocOption sdocPrintTypecheckerElaboration $ \case
False -> pprLHsBinds val_binds
True -> -- Show extra information (bug number: #10662)
hang (text "AbsBinds"
<+> sep [ brackets (interpp'SP tyvars)
, brackets (interpp'SP dictvars) ])
2 $ braces $ vcat
[ text "Exports:" <+>
brackets (sep (punctuate comma (map ppr exports)))
, text "Exported types:" <+>
vcat [pprBndr LetBind (abe_poly ex) | ex <- exports]
, text "Binds:" <+> pprLHsBinds val_binds
, pprIfTc @idR (text "Evidence:" <+> ppr ev_binds)
]
instance Outputable ABExport where
ppr (ABE { abe_wrap = wrap, abe_poly = gbl, abe_mono = lcl, abe_prags = prags })
= vcat [ sep [ ppr gbl, nest 2 (text "<=" <+> ppr lcl) ]
, nest 2 (pprTcSpecPrags prags)
, ppr $ nest 2 (text "wrap:" <+> ppr wrap) ]
instance (OutputableBndrId l, OutputableBndrId r)
=> Outputable (PatSynBind (GhcPass l) (GhcPass r)) where
ppr (PSB{ psb_id = (L _ psyn), psb_args = details, psb_def = pat,
psb_dir = dir })
= ppr_lhs <+> ppr_rhs
where
ppr_lhs = text "pattern" <+> ppr_details
ppr_simple syntax = syntax <+> pprLPat pat
ppr_details = case details of
InfixCon v1 v2 -> hsep [ppr_v v1, pprInfixOcc psyn, ppr_v v2]
where
ppr_v v = case ghcPass @r of
GhcPs -> ppr v
GhcRn -> ppr v
GhcTc -> ppr v
PrefixCon vs -> hsep (pprPrefixOcc psyn : map ppr_v vs)
where
ppr_v v = case ghcPass @r of
GhcPs -> ppr v
GhcRn -> ppr v
GhcTc -> ppr v
RecCon vs -> pprPrefixOcc psyn
<> braces (sep (punctuate comma (map ppr_v vs)))
where
ppr_v v = case ghcPass @r of
GhcPs -> ppr v
GhcRn -> ppr v
GhcTc -> ppr v
ppr_rhs = case dir of
Unidirectional -> ppr_simple larrow
ImplicitBidirectional -> ppr_simple equals
ExplicitBidirectional mg -> ppr_simple larrow <+> text "where" $$
(nest 2 $ pprFunBind mg)
pprTicks :: SDoc -> SDoc -> SDoc
-- Print stuff about ticks only when -dppr-debug is on, to avoid
-- them appearing in error messages (from the desugarer); see # 3263
-- Also print ticks in dumpStyle, so that -ddump-hpc actually does
-- something useful.
pprTicks pp_no_debug pp_when_debug
= getPprStyle $ \sty ->
getPprDebug $ \debug ->
if debug || dumpStyle sty
then pp_when_debug
else pp_no_debug
instance Outputable (XRecGhc (IdGhcP p)) => Outputable (RecordPatSynField (GhcPass p)) where
ppr (RecordPatSynField { recordPatSynField = v }) = ppr v
{-
************************************************************************
* *
Implicit parameter bindings
* *
************************************************************************
-}
type instance XIPBinds GhcPs = NoExtField
type instance XIPBinds GhcRn = NoExtField
type instance XIPBinds GhcTc = TcEvBinds -- binds uses of the
-- implicit parameters
type instance XXHsIPBinds (GhcPass p) = DataConCantHappen
isEmptyIPBindsPR :: HsIPBinds (GhcPass p) -> Bool
isEmptyIPBindsPR (IPBinds _ is) = null is
isEmptyIPBindsTc :: HsIPBinds GhcTc -> Bool
isEmptyIPBindsTc (IPBinds ds is) = null is && isEmptyTcEvBinds ds
-- EPA annotations in GhcPs, dictionary Id in GhcTc
type instance XCIPBind GhcPs = EpToken "="
type instance XCIPBind GhcRn = NoExtField
type instance XCIPBind GhcTc = Id
type instance XXIPBind (GhcPass p) = DataConCantHappen
instance OutputableBndrId p
=> Outputable (HsIPBinds (GhcPass p)) where
ppr (IPBinds ds bs) = pprDeeperList vcat (map ppr bs)
$$ whenPprDebug (pprIfTc @p $ ppr ds)
instance OutputableBndrId p => Outputable (IPBind (GhcPass p)) where
ppr (IPBind x (L _ ip) rhs) = name <+> equals <+> pprExpr (unLoc rhs)
where name = case ghcPass @p of
GhcPs -> pprBndr LetBind ip
GhcRn -> pprBndr LetBind ip
GhcTc -> pprBndr LetBind x
{-
************************************************************************
* *
\subsection{@Sig@: type signatures and value-modifying user pragmas}
* *
************************************************************************
-}
type instance XTypeSig (GhcPass p) = AnnSig
type instance XPatSynSig (GhcPass p) = AnnSig
type instance XClassOpSig (GhcPass p) = AnnSig
type instance XFixSig (GhcPass p) = ((EpaLocation, Maybe EpaLocation), SourceText)
type instance XInlineSig (GhcPass p) = (EpaLocation, EpToken "#-}", ActivationAnn)
type instance XSpecSig (GhcPass p) = AnnSpecSig
type instance XSpecInstSig (GhcPass p) = ((EpaLocation, EpToken "instance", EpToken "#-}"), SourceText)
type instance XMinimalSig (GhcPass p) = ((EpaLocation, EpToken "#-}"), SourceText)
type instance XSCCFunSig (GhcPass p) = ((EpaLocation, EpToken "#-}"), SourceText)
type instance XCompleteMatchSig (GhcPass p) = ((EpaLocation, Maybe TokDcolon, EpToken "#-}"), SourceText)
type instance XSpecSigE GhcPs = AnnSpecSig
type instance XSpecSigE GhcRn = Name
type instance XSpecSigE GhcTc = NoExtField
-- SourceText: See Note [Pragma source text] in "GHC.Types.SourceText"
type instance XXSig GhcPs = DataConCantHappen
type instance XXSig GhcRn = IdSig
type instance XXSig GhcTc = IdSig
type instance XFixitySig GhcPs = NamespaceSpecifier
type instance XFixitySig GhcRn = NamespaceSpecifier
type instance XFixitySig GhcTc = NoExtField
type instance XXFixitySig (GhcPass p) = DataConCantHappen
data AnnSpecSig
= AnnSpecSig {
ass_open :: EpaLocation,
ass_close :: EpToken "#-}",
ass_dcolon :: Maybe TokDcolon, -- Only for old SpecSig, remove when it goes
ass_act :: ActivationAnn
} deriving Data
instance NoAnn AnnSpecSig where
noAnn = AnnSpecSig noAnn noAnn noAnn noAnn
data ActivationAnn
= ActivationAnn {
aa_openc :: EpToken "[",
aa_closec :: EpToken "]",
aa_tilde :: Maybe (EpToken "~"),
aa_val :: Maybe EpaLocation
} deriving (Data, Eq)
instance NoAnn ActivationAnn where
noAnn = ActivationAnn noAnn noAnn noAnn noAnn
-- | Optional namespace specifier for fixity signatures,
-- WARNINIG and DEPRECATED pragmas.
--
-- Examples:
--
-- {-# WARNING in "x-partial" data Head "don't use this pattern synonym" #-}
-- -- ↑ DataNamespaceSpecifier
--
-- {-# DEPRECATED type D "This type was deprecated" #-}
-- -- ↑ TypeNamespaceSpecifier
--
-- infixr 6 data $
-- -- ↑ DataNamespaceSpecifier
data NamespaceSpecifier
= NoNamespaceSpecifier
| TypeNamespaceSpecifier (EpToken "type")
| DataNamespaceSpecifier (EpToken "data")
deriving (Eq, Data)
-- | Check if namespace specifiers overlap, i.e. if they are equal or
-- if at least one of them doesn't specify a namespace
overlappingNamespaceSpecifiers :: NamespaceSpecifier -> NamespaceSpecifier -> Bool
overlappingNamespaceSpecifiers NoNamespaceSpecifier _ = True
overlappingNamespaceSpecifiers _ NoNamespaceSpecifier = True
overlappingNamespaceSpecifiers TypeNamespaceSpecifier{} TypeNamespaceSpecifier{} = True
overlappingNamespaceSpecifiers DataNamespaceSpecifier{} DataNamespaceSpecifier{} = True
overlappingNamespaceSpecifiers _ _ = False
-- | Check if namespace is covered by a namespace specifier:
-- * NoNamespaceSpecifier covers both namespaces
-- * TypeNamespaceSpecifier covers the type namespace only
-- * DataNamespaceSpecifier covers the data namespace only
coveredByNamespaceSpecifier :: NamespaceSpecifier -> NameSpace -> Bool
coveredByNamespaceSpecifier NoNamespaceSpecifier = const True
coveredByNamespaceSpecifier TypeNamespaceSpecifier{} = isTcClsNameSpace <||> isTvNameSpace
coveredByNamespaceSpecifier DataNamespaceSpecifier{} = isValNameSpace
instance Outputable NamespaceSpecifier where
ppr NoNamespaceSpecifier = empty
ppr TypeNamespaceSpecifier{} = text "type"
ppr DataNamespaceSpecifier{} = text "data"
-- | A type signature in generated code, notably the code
-- generated for record selectors. We simply record the desired Id
-- itself, replete with its name, type and IdDetails. Otherwise it's
-- just like a type signature: there should be an accompanying binding
newtype IdSig = IdSig { unIdSig :: Id }
deriving Data
data AnnSig
= AnnSig {
asDcolon :: EpUniToken "::" "∷",
asPattern :: Maybe (EpToken "pattern"),
asDefault :: Maybe (EpToken "default")
} deriving Data
instance NoAnn AnnSig where
noAnn = AnnSig noAnn noAnn noAnn
-- | Type checker Specialisation Pragmas
--
-- 'TcSpecPrags' conveys @SPECIALISE@ pragmas from the type checker
-- to the desugarer
data TcSpecPrags
= IsDefaultMethod -- ^ Super-specialised: a default method should
-- be macro-expanded at every call site
| SpecPrags [LTcSpecPrag]
-- | Located Type checker Specialisation Pragmas
type LTcSpecPrag = Located TcSpecPrag
-- | Type checker Specialisation Pragma
--
-- This data type is used to communicate between the typechecker and
-- the desugarer.
data TcSpecPrag
-- | Old-form specialise pragma
= SpecPrag
Id
-- ^ 'Id' to be specialised
HsWrapper
-- ^ wrapper that specialises the polymorphic function
InlinePragma
-- ^ inlining spec for the specialised function
-- | New-form specialise pragma
| SpecPragE
{ spe_fn_nm :: Name
-- ^ 'Name' of the 'Id' being specialised
, spe_fn_id :: Id
-- ^ 'Id' being specialised
--
-- Note that 'spe_fn_nm' may differ from @'idName' 'spe_fn_id'@
-- in the case of instance methods, where the 'Name' is the
-- class-op selector but the 'spe_fn_id' is that for the local method
, spe_inl :: InlinePragma
-- ^ (optional) INLINE annotation and activation phase annotation
, spe_bndrs :: [Var]
-- ^ TyVars, EvVars, and Ids
, spe_call :: LHsExpr GhcTc
-- ^ The type-checked specialise expression
}
noSpecPrags :: TcSpecPrags
noSpecPrags = SpecPrags []
hasSpecPrags :: TcSpecPrags -> Bool
hasSpecPrags (SpecPrags ps) = not (null ps)
hasSpecPrags IsDefaultMethod = False
isDefaultMethod :: TcSpecPrags -> Bool
isDefaultMethod IsDefaultMethod = True
isDefaultMethod (SpecPrags {}) = False
instance OutputableBndrId p => Outputable (Sig (GhcPass p)) where
ppr sig = ppr_sig sig
ppr_sig :: forall p. OutputableBndrId p
=> Sig (GhcPass p) -> SDoc
ppr_sig (TypeSig _ vars ty) = pprVarSig (map unLoc vars) (ppr ty)
ppr_sig (ClassOpSig _ is_deflt vars ty)
| is_deflt = text "default" <+> pprVarSig (map unLoc vars) (ppr ty)
| otherwise = pprVarSig (map unLoc vars) (ppr ty)
ppr_sig (FixSig _ fix_sig) = ppr fix_sig
ppr_sig (SpecSig _ var ty inl@(InlinePragma { inl_src = src, inl_inline = spec }))
= pragSrcBrackets (inlinePragmaSource inl) pragmaSrc $
pprSpec (unLoc var) (interpp'SP ty) inl
where
pragmaSrc = case spec of
NoUserInlinePrag -> "{-# " ++ extractSpecPragName src
_ -> "{-# " ++ extractSpecPragName src ++ "_INLINE"
ppr_sig (SpecSigE _ bndrs spec_e inl@(InlinePragma { inl_src = src, inl_inline = spec }))
= pragSrcBrackets (inlinePragmaSource inl) pragmaSrc $
pp_inl <+> hang (ppr bndrs) 2 (pprLExpr spec_e)
where
-- SPECIALISE or SPECIALISE_INLINE
pragmaSrc = case spec of
NoUserInlinePrag -> "{-# " ++ extractSpecPragName src
_ -> "{-# " ++ extractSpecPragName src ++ "_INLINE"
pp_inl | isDefaultInlinePragma inl = empty
| otherwise = pprInline inl
ppr_sig (InlineSig _ var inl)
= ppr_pfx <+> pprInline inl <+> pprPrefixOcc (unLoc var) <+> text "#-}"
where
ppr_pfx = case inlinePragmaSource inl of
SourceText src -> ftext src
NoSourceText -> text "{-#" <+> inlinePragmaName (inl_inline inl)
ppr_sig (SpecInstSig (_, src) ty)
= pragSrcBrackets src "{-# pragma" (text "instance" <+> ppr ty)
ppr_sig (MinimalSig (_, src) bf)
= pragSrcBrackets src "{-# MINIMAL" (pprMinimalSig bf)
ppr_sig (PatSynSig _ names sig_ty)
= text "pattern" <+> pprVarSig (map unLoc names) (ppr sig_ty)
ppr_sig (SCCFunSig (_, src) fn mlabel)
= pragSrcBrackets src "{-# SCC" (ppr_fn <+> maybe empty ppr mlabel )
where
ppr_fn = case ghcPass @p of
GhcPs -> ppr fn
GhcRn -> ppr fn
GhcTc -> ppr fn
ppr_sig (CompleteMatchSig (_, src) cs mty)
= pragSrcBrackets src "{-# COMPLETE"
((hsep (punctuate comma (map ppr_n cs)))
<+> opt_sig)
where
opt_sig = maybe empty ((\t -> dcolon <+> ppr t) . unLoc) mty
ppr_n n = case ghcPass @p of
GhcPs -> ppr n
GhcRn -> ppr n
GhcTc -> ppr n
ppr_sig (XSig x) = case ghcPass @p of
GhcRn | IdSig id <- x -> pprVarSig [id] (ppr (varType id))
GhcTc | IdSig id <- x -> pprVarSig [id] (ppr (varType id))
hsSigDoc :: forall p. IsPass p => Sig (GhcPass p) -> SDoc
hsSigDoc (TypeSig {}) = text "type signature"
hsSigDoc (PatSynSig {}) = text "pattern synonym signature"
hsSigDoc (ClassOpSig _ is_deflt _ _)
| is_deflt = text "default type signature"
| otherwise = text "class method signature"
hsSigDoc (SpecSig _ _ _ inl) = (inlinePragmaName . inl_inline $ inl) <+> text "pragma"
hsSigDoc (SpecSigE _ _ _ inl) = (inlinePragmaName . inl_inline $ inl) <+> text "pragma"
hsSigDoc (InlineSig _ _ prag) = (inlinePragmaName . inl_inline $ prag) <+> text "pragma"
-- Using the 'inlinePragmaName' function ensures that the pragma name for any
-- one of the INLINE/INLINABLE/NOINLINE pragmas are printed after being extracted
-- from the InlineSpec field of the pragma.
hsSigDoc (SpecInstSig (_, src) _) = text (extractSpecPragName src) <+> text "instance pragma"
hsSigDoc (FixSig {}) = text "fixity declaration"
hsSigDoc (MinimalSig {}) = text "MINIMAL pragma"
hsSigDoc (SCCFunSig {}) = text "SCC pragma"
hsSigDoc (CompleteMatchSig {}) = text "COMPLETE pragma"
hsSigDoc (XSig _) = case ghcPass @p of
GhcRn -> text "id signature"
GhcTc -> text "id signature"
-- | Extracts the name for a SPECIALIZE instance pragma. In 'hsSigDoc', the src
-- field of 'SpecInstSig' signature contains the SourceText for a SPECIALIZE
-- instance pragma of the form: "SourceText {-# SPECIALIZE"
--
-- Extraction ensures that all variants of the pragma name (with a 'Z' or an
-- 'S') are output exactly as used in the pragma.
extractSpecPragName :: SourceText -> String
extractSpecPragName srcTxt = case (words $ show srcTxt) of
(_:_:pragName:_) -> filter (/= '\"') pragName
_ -> pprPanic "hsSigDoc: Misformed SPECIALISE instance pragma:" (ppr srcTxt)
instance OutputableBndrId p
=> Outputable (FixitySig (GhcPass p)) where
ppr (FixitySig ns_spec names fixity) = sep [ppr fixity, ppr_ns_spec, pprops]
where
ppr_ns_spec =
case ghcPass @p of
GhcPs -> ppr ns_spec
GhcRn -> ppr ns_spec
GhcTc -> empty
pprops = hsep $ punctuate comma (map (pprInfixOcc . unLoc) names)
pragBrackets :: SDoc -> SDoc
pragBrackets doc = text "{-#" <+> doc <+> text "#-}"
-- | Using SourceText in case the pragma was spelled differently or used mixed
-- case
pragSrcBrackets :: SourceText -> String -> SDoc -> SDoc
pragSrcBrackets (SourceText src) _ doc = ftext src <+> doc <+> text "#-}"
pragSrcBrackets NoSourceText alt doc = text alt <+> doc <+> text "#-}"
pprVarSig :: (OutputableBndr id) => [id] -> SDoc -> SDoc
pprVarSig vars pp_ty = sep [pprvars <+> dcolon, nest 2 pp_ty]
where
pprvars = hsep $ punctuate comma (map pprPrefixOcc vars)
pprSpec :: (OutputableBndr id) => id -> SDoc -> InlinePragma -> SDoc
pprSpec var pp_ty inl = pp_inl <+> pprVarSig [var] pp_ty
where
pp_inl | isDefaultInlinePragma inl = empty
| otherwise = pprInline inl
pprTcSpecPrags :: TcSpecPrags -> SDoc
pprTcSpecPrags IsDefaultMethod = text "<default method>"
pprTcSpecPrags (SpecPrags ps) = vcat (map (ppr . unLoc) ps)
instance Outputable TcSpecPrag where
ppr (SpecPrag var _ inl)
= text (extractSpecPragName $ inl_src inl) <+> pprSpec var (text "<type>") inl
ppr (SpecPragE { spe_bndrs = bndrs, spe_call = spec_e, spe_inl = inl })
= text (extractSpecPragName $ inl_src inl)
<+> hang (ppr bndrs) 2 (pprLExpr spec_e)
pprMinimalSig :: OutputableBndrId p => LBooleanFormula (GhcPass p) -> SDoc
pprMinimalSig (L _ bf) = pprBooleanFormulaNormal bf
{- *********************************************************************
* *
RuleBndrs
* *
********************************************************************* -}
data HsRuleBndrsAnn
= HsRuleBndrsAnn
{ rb_tyanns :: Maybe (TokForall, EpToken ".")
-- ^ The locations of 'forall' and '.' for forall'd type vars
-- Using AddEpAnn to capture possible unicode variants
, rb_tmanns :: Maybe (TokForall, EpToken ".")
-- ^ The locations of 'forall' and '.' for forall'd term vars
-- Using AddEpAnn to capture possible unicode variants
} deriving (Data, Eq)
instance NoAnn HsRuleBndrsAnn where
noAnn = HsRuleBndrsAnn Nothing Nothing
type instance XXRuleBndrs (GhcPass _) = DataConCantHappen
type instance XCRuleBndrs GhcPs = HsRuleBndrsAnn
type instance XCRuleBndrs GhcRn = NoExtField
type instance XCRuleBndrs GhcTc = [Var] -- Binders of the rule, not
-- necessarily in dependency order
type instance XRuleBndrSig (GhcPass _) = AnnTyVarBndr
type instance XCRuleBndr (GhcPass _) = AnnTyVarBndr
type instance XXRuleBndr (GhcPass _) = DataConCantHappen
instance (OutputableBndrId p) => Outputable (RuleBndrs (GhcPass p)) where
ppr (RuleBndrs { rb_tyvs = tyvs, rb_tmvs = tmvs })
= pp_forall_ty tyvs <+> pp_forall_tm tyvs
where
pp_forall_ty Nothing = empty
pp_forall_ty (Just qtvs) = forAllLit <+> fsep (map ppr qtvs) <> dot
pp_forall_tm Nothing | null tmvs = empty
pp_forall_tm _ = forAllLit <+> fsep (map ppr tmvs) <> dot
instance (OutputableBndrId p) => Outputable (RuleBndr (GhcPass p)) where
ppr (RuleBndr _ name) = ppr name
ppr (RuleBndrSig _ name ty) = parens (ppr name <> dcolon <> ppr ty)
{-
************************************************************************
* *
\subsection{Anno instances}
* *
************************************************************************
-}
type instance Anno (HsBindLR (GhcPass idL) (GhcPass idR)) = SrcSpanAnnA
type instance Anno (IPBind (GhcPass p)) = SrcSpanAnnA
type instance Anno (Sig (GhcPass p)) = SrcSpanAnnA
type instance Anno (RuleBndr (GhcPass p)) = EpAnnCO
type instance Anno (FixitySig (GhcPass p)) = SrcSpanAnnA
type instance Anno StringLiteral = EpAnnCO