{-# LANGUAGE PatternSynonyms #-}

{-| Functions for inserting implicit arguments at the right places.
-}
module Agda.TypeChecking.Implicit where

import Control.Monad
import Control.Monad.Except
import Control.Monad.IO.Class

import Agda.Syntax.Position (HasRange, beginningOf, getRange)
import Agda.Syntax.Common
import Agda.Syntax.Abstract (Binder, mkBinder_)
import Agda.Syntax.Info ( MetaKind (InstanceMeta, UnificationMeta) )
import Agda.Syntax.Internal as I

import Agda.TypeChecking.Irrelevance
import {-# SOURCE #-} Agda.TypeChecking.MetaVars
import {-# SOURCE #-} Agda.TypeChecking.Rules.Term (unquoteTactic)
import Agda.TypeChecking.Monad
import Agda.TypeChecking.Reduce
import Agda.TypeChecking.Substitute
import Agda.TypeChecking.Pretty
import Agda.TypeChecking.Telescope

import Agda.Utils.Function (applyWhen)
import Agda.Utils.Functor
import Agda.Utils.List1 (List1, pattern (:|))
import qualified Agda.Utils.List1 as List1
import Agda.Utils.Maybe
import Agda.Utils.Tuple

-- Cut and paste from insertImplicitPatternsT:

-- | Split a given Pi 'Type' until you reach the given named argument,
-- returning the number of arguments skipped to reach the right plicity
-- and name.
splitImplicitBinderT :: HasRange a => NamedArg a -> Type -> TCM (Telescope, Type)
splitImplicitBinderT :: forall a. HasRange a => NamedArg a -> Type -> TCM (Telescope, Type)
splitImplicitBinderT NamedArg a
narg Type
ty = do
  -- Split off any invisible arguments at the front (so if the first
  -- argument is visible, return tel = EmptyTel)
  TelV tel ty0 <- Int -> (Dom Type -> Bool) -> Type -> TCMT IO (TelV Type)
forall (m :: * -> *).
(MonadReduce m, MonadAddContext m) =>
Int -> (Dom Type -> Bool) -> Type -> m (TelV Type)
telViewUpTo' (-Int
1) (Bool -> Bool
not (Bool -> Bool) -> (Dom Type -> Bool) -> Dom Type -> Bool
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Dom Type -> Bool
forall a. LensHiding a => a -> Bool
visible) Type
ty

  case tel of
    -- If we didn't lob off any arguments then we can use the original
    -- type and the empty telescope
    Telescope
EmptyTel -> (Telescope, Type) -> TCM (Telescope, Type)
forall a. a -> TCMT IO a
forall (f :: * -> *) a. Applicative f => a -> f a
pure (Telescope
forall a. Tele a
EmptyTel, Type
ty)

    -- Otherwise we try inserting implicit arguments.
    Telescope
_ -> NamedArg a -> TCM (Telescope, Type) -> TCM (Telescope, Type)
forall (m :: * -> *) x a.
(MonadTrace m, HasRange x) =>
x -> m a -> m a
setCurrentRange NamedArg a
narg case NamedArg a -> [Dom (ArgName, Type)] -> ImplicitInsertion
forall e a. NamedArg e -> [Dom a] -> ImplicitInsertion
insertImplicit NamedArg a
narg ([Dom (ArgName, Type)] -> ImplicitInsertion)
-> [Dom (ArgName, Type)] -> ImplicitInsertion
forall a b. (a -> b) -> a -> b
$ Telescope -> [Dom (ArgName, Type)]
forall t. Tele (Dom t) -> [Dom (ArgName, t)]
telToList Telescope
tel of
      ImplicitInsertion
BadImplicits   -> TypeError -> TCM (Telescope, Type)
forall (m :: * -> *) a.
(HasCallStack, MonadTCError m) =>
TypeError -> m a
typeError TypeError
WrongHidingInLHS
      NoSuchName ArgName
x   -> TypeError -> TCM (Telescope, Type)
forall (m :: * -> *) a.
(HasCallStack, MonadTCError m) =>
TypeError -> m a
typeError TypeError
WrongHidingInLHS
      ImpInsert [Dom ()]
doms ->
        let (Telescope
here, Telescope
there) = Int -> Telescope -> (Telescope, Telescope)
splitTelescopeAt ([Dom ()] -> Int
forall a. [a] -> Int
forall (t :: * -> *) a. Foldable t => t a -> Int
length [Dom ()]
doms) Telescope
tel
        in (Telescope, Type) -> TCM (Telescope, Type)
forall a. a -> TCMT IO a
forall (f :: * -> *) a. Applicative f => a -> f a
pure (Telescope
here, Telescope -> Type -> Type
forall t. Abstract t => Telescope -> t -> t
abstract Telescope
there Type
ty0)

-- | @implicitArgs n expand t@ generates up to @n@ implicit argument
--   metas (unbounded if @n<0@), as long as @t@ is a function type
--   and @expand@ holds on the hiding info of its domain.

implicitArgs
  :: (PureTCM m, MonadMetaSolver m, MonadTCM m)
  => Int               -- ^ @n@, the maximum number of implicts to be inserted.
  -> (Hiding -> Bool)  -- ^ @expand@, the predicate to test whether we should keep inserting.
  -> Type              -- ^ The (function) type @t@ we are eliminating.
  -> m (Args, Type)  -- ^ The eliminating arguments and the remaining type.
implicitArgs :: forall (m :: * -> *).
(PureTCM m, MonadMetaSolver m, MonadTCM m) =>
Int -> (Hiding -> Bool) -> Type -> m (Args, Type)
implicitArgs Int
n Hiding -> Bool
expand Type
t = ([Arg (Named NamedName Term)] -> Args)
-> ([Arg (Named NamedName Term)], Type) -> (Args, Type)
forall a c b. (a -> c) -> (a, b) -> (c, b)
mapFst ((Arg (Named NamedName Term) -> Arg Term)
-> [Arg (Named NamedName Term)] -> Args
forall a b. (a -> b) -> [a] -> [b]
map ((Named NamedName Term -> Term)
-> Arg (Named NamedName Term) -> Arg Term
forall a b. (a -> b) -> Arg a -> Arg b
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
fmap Named NamedName Term -> Term
forall name a. Named name a -> a
namedThing)) (([Arg (Named NamedName Term)], Type) -> (Args, Type))
-> m ([Arg (Named NamedName Term)], Type) -> m (Args, Type)
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> do
  Int
-> (Hiding -> ArgName -> Bool)
-> Type
-> m ([Arg (Named NamedName Term)], Type)
forall (m :: * -> *).
(PureTCM m, MonadMetaSolver m, MonadTCM m) =>
Int
-> (Hiding -> ArgName -> Bool)
-> Type
-> m ([Arg (Named NamedName Term)], Type)
implicitNamedArgs Int
n (\ Hiding
h ArgName
x -> Hiding -> Bool
expand Hiding
h) Type
t

-- | @implicitNamedArgs n expand t@ generates up to @n@ named implicit arguments
--   metas (unbounded if @n<0@), as long as @t@ is a function type
--   and @expand@ holds on the hiding and name info of its domain.

implicitNamedArgs
  :: (PureTCM m, MonadMetaSolver m, MonadTCM m)
  => Int                          -- ^ @n@, the maximum number of implicts to be inserted.
  -> (Hiding -> ArgName -> Bool)  -- ^ @expand@, the predicate to test whether we should keep inserting.
  -> Type                         -- ^ The (function) type @t@ we are eliminating.
  -> m (NamedArgs, Type)        -- ^ The eliminating arguments and the remaining type.
implicitNamedArgs :: forall (m :: * -> *).
(PureTCM m, MonadMetaSolver m, MonadTCM m) =>
Int
-> (Hiding -> ArgName -> Bool)
-> Type
-> m ([Arg (Named NamedName Term)], Type)
implicitNamedArgs Int
0 Hiding -> ArgName -> Bool
expand Type
t0 = ([Arg (Named NamedName Term)], Type)
-> m ([Arg (Named NamedName Term)], Type)
forall a. a -> m a
forall (m :: * -> *) a. Monad m => a -> m a
return ([], Type
t0)
implicitNamedArgs Int
n Hiding -> ArgName -> Bool
expand Type
t0 = do
    t0' <- Type -> m Type
forall a (m :: * -> *). (Reduce a, MonadReduce m) => a -> m a
reduce Type
t0
    reportSDoc "tc.term.args" 30 $ "implicitNamedArgs" <+> prettyTCM t0'
    reportSDoc "tc.term.args" 80 $ "implicitNamedArgs" <+> text (show t0')
    case unEl t0' of
      Pi dom :: Dom Type
dom@Dom{domInfo :: forall t e. Dom' t e -> ArgInfo
domInfo = ArgInfo
info, domTactic :: forall t e. Dom' t e -> Maybe t
domTactic = Maybe Term
tac, unDom :: forall t e. Dom' t e -> e
unDom = Type
a} Abs Type
b
        | let x :: ArgName
x = ArgName -> Dom Type -> ArgName
forall a.
(LensNamed a, NameOf a ~ NamedName) =>
ArgName -> a -> ArgName
bareNameWithDefault ArgName
"_" Dom Type
dom, Hiding -> ArgName -> Bool
expand (ArgInfo -> Hiding
forall a. LensHiding a => a -> Hiding
getHiding ArgInfo
info) ArgName
x -> do
          kind <- if ArgInfo -> Bool
forall a. LensHiding a => a -> Bool
hidden ArgInfo
info then MetaKind -> m MetaKind
forall a. a -> m a
forall (m :: * -> *) a. Monad m => a -> m a
return MetaKind
UnificationMeta else do
            ArgName -> Int -> TCMT IO Doc -> m ()
forall (m :: * -> *).
MonadDebug m =>
ArgName -> Int -> TCMT IO Doc -> m ()
reportSDoc ArgName
"tc.term.args.ifs" Int
15 (TCMT IO Doc -> m ()) -> TCMT IO Doc -> m ()
forall a b. (a -> b) -> a -> b
$
              TCMT IO Doc
"inserting instance meta for type" TCMT IO Doc -> TCMT IO Doc -> TCMT IO Doc
forall (m :: * -> *). Applicative m => m Doc -> m Doc -> m Doc
<+> Type -> TCMT IO Doc
forall a (m :: * -> *). (PrettyTCM a, MonadPretty m) => a -> m Doc
forall (m :: * -> *). MonadPretty m => Type -> m Doc
prettyTCM Type
a
            ArgName -> Int -> TCMT IO Doc -> m ()
forall (m :: * -> *).
MonadDebug m =>
ArgName -> Int -> TCMT IO Doc -> m ()
reportSDoc ArgName
"tc.term.args.ifs" Int
40 (TCMT IO Doc -> m ()) -> TCMT IO Doc -> m ()
forall a b. (a -> b) -> a -> b
$ Int -> TCMT IO Doc -> TCMT IO Doc
forall (m :: * -> *). Functor m => Int -> m Doc -> m Doc
nest Int
2 (TCMT IO Doc -> TCMT IO Doc) -> TCMT IO Doc -> TCMT IO Doc
forall a b. (a -> b) -> a -> b
$ [TCMT IO Doc] -> TCMT IO Doc
forall (m :: * -> *) (t :: * -> *).
(Applicative m, Foldable t) =>
t (m Doc) -> m Doc
vcat
              [ TCMT IO Doc
"x      = " TCMT IO Doc -> TCMT IO Doc -> TCMT IO Doc
forall (m :: * -> *). Applicative m => m Doc -> m Doc -> m Doc
<+> ArgName -> TCMT IO Doc
forall (m :: * -> *). Applicative m => ArgName -> m Doc
text (ArgName -> ArgName
forall a. Show a => a -> ArgName
show ArgName
x)
              , TCMT IO Doc
"hiding = " TCMT IO Doc -> TCMT IO Doc -> TCMT IO Doc
forall (m :: * -> *). Applicative m => m Doc -> m Doc -> m Doc
<+> ArgName -> TCMT IO Doc
forall (m :: * -> *). Applicative m => ArgName -> m Doc
text (Hiding -> ArgName
forall a. Show a => a -> ArgName
show (Hiding -> ArgName) -> Hiding -> ArgName
forall a b. (a -> b) -> a -> b
$ ArgInfo -> Hiding
forall a. LensHiding a => a -> Hiding
getHiding ArgInfo
info)
              ]

            MetaKind -> m MetaKind
forall a. a -> m a
forall (m :: * -> *) a. Monad m => a -> m a
return MetaKind
InstanceMeta
          (_, v) <- newMetaArg kind info x CmpLeq a
          whenJust tac $ \ Term
tac -> TCM () -> m ()
forall a. TCM a -> m a
forall (tcm :: * -> *) a. MonadTCM tcm => TCM a -> tcm a
liftTCM (TCM () -> m ()) -> TCM () -> m ()
forall a b. (a -> b) -> a -> b
$
            ArgInfo -> TCM () -> TCM ()
forall (tcm :: * -> *) m a.
(MonadTCEnv tcm, LensModality m) =>
m -> tcm a -> tcm a
applyModalityToContext ArgInfo
info (TCM () -> TCM ()) -> TCM () -> TCM ()
forall a b. (a -> b) -> a -> b
$ Term -> Term -> Type -> TCM ()
unquoteTactic Term
tac Term
v Type
a
          let narg = ArgInfo -> Named NamedName Term -> Arg (Named NamedName Term)
forall e. ArgInfo -> e -> Arg e
Arg ArgInfo
info (Maybe NamedName -> Term -> Named NamedName Term
forall name a. Maybe name -> a -> Named name a
Named (NamedName -> Maybe NamedName
forall a. a -> Maybe a
Just (NamedName -> Maybe NamedName) -> NamedName -> Maybe NamedName
forall a b. (a -> b) -> a -> b
$ Origin -> Ranged ArgName -> NamedName
forall a. Origin -> a -> WithOrigin a
WithOrigin Origin
Inserted (Ranged ArgName -> NamedName) -> Ranged ArgName -> NamedName
forall a b. (a -> b) -> a -> b
$ ArgName -> Ranged ArgName
forall a. a -> Ranged a
unranged ArgName
x) Term
v)
          mapFst (narg :) <$> implicitNamedArgs (n-1) expand (absApp b v)
      Term
_ -> ([Arg (Named NamedName Term)], Type)
-> m ([Arg (Named NamedName Term)], Type)
forall a. a -> m a
forall (m :: * -> *) a. Monad m => a -> m a
return ([], Type
t0')

-- | Create a metavariable of 'MetaKind'.

newMetaArg
  :: (PureTCM m, MonadMetaSolver m)
  => MetaKind   -- ^ Kind of meta.
  -> ArgInfo    -- ^ Rrelevance of meta.
  -> ArgName    -- ^ Name suggestion for meta.
  -> Comparison -- ^ Check (@CmpLeq@) or infer (@CmpEq@) the type.
  -> Type       -- ^ Type of meta.
  -> m (MetaId, Term)  -- ^ The created meta as id and as term.
newMetaArg :: forall (m :: * -> *).
(PureTCM m, MonadMetaSolver m) =>
MetaKind
-> ArgInfo -> ArgName -> Comparison -> Type -> m (MetaId, Term)
newMetaArg MetaKind
kind ArgInfo
info ArgName
x Comparison
cmp Type
a = do
  prp <- BlockT m Bool -> m (Either Blocker Bool)
forall (m :: * -> *) a.
Monad m =>
BlockT m a -> m (Either Blocker a)
runBlocked (BlockT m Bool -> m (Either Blocker Bool))
-> BlockT m Bool -> m (Either Blocker Bool)
forall a b. (a -> b) -> a -> b
$ Type -> BlockT m Bool
forall a (m :: * -> *).
(LensSort a, PrettyTCM a, PureTCM m, MonadBlock m) =>
a -> m Bool
isPropM Type
a
  let irrelevantIfProp =
        Bool
-> (m (MetaId, Term) -> m (MetaId, Term))
-> m (MetaId, Term)
-> m (MetaId, Term)
forall b a. IsBool b => b -> (a -> a) -> a -> a
applyWhen (Either Blocker Bool
prp Either Blocker Bool -> Either Blocker Bool -> Bool
forall a. Eq a => a -> a -> Bool
== Bool -> Either Blocker Bool
forall a b. b -> Either a b
Right Bool
True) ((m (MetaId, Term) -> m (MetaId, Term))
 -> m (MetaId, Term) -> m (MetaId, Term))
-> (m (MetaId, Term) -> m (MetaId, Term))
-> m (MetaId, Term)
-> m (MetaId, Term)
forall a b. (a -> b) -> a -> b
$ Relevance -> m (MetaId, Term) -> m (MetaId, Term)
forall (tcm :: * -> *) r a.
(MonadTCEnv tcm, LensRelevance r) =>
r -> tcm a -> tcm a
applyRelevanceToContext Relevance
irrelevant
  applyModalityToContext info $ irrelevantIfProp $
    newMeta (argNameToString x) kind a
  where
    newMeta :: MonadMetaSolver m => String -> MetaKind -> Type -> m (MetaId, Term)
    newMeta :: forall (m :: * -> *).
MonadMetaSolver m =>
ArgName -> MetaKind -> Type -> m (MetaId, Term)
newMeta ArgName
n = \case
      MetaKind
InstanceMeta    -> ArgName -> Type -> m (MetaId, Term)
forall (m :: * -> *).
MonadMetaSolver m =>
ArgName -> Type -> m (MetaId, Term)
newInstanceMeta ArgName
n
      MetaKind
UnificationMeta -> RunMetaOccursCheck
-> ArgName -> Comparison -> Type -> m (MetaId, Term)
forall (m :: * -> *).
MonadMetaSolver m =>
RunMetaOccursCheck
-> ArgName -> Comparison -> Type -> m (MetaId, Term)
newNamedValueMeta RunMetaOccursCheck
RunMetaOccursCheck ArgName
n Comparison
cmp

-- | Create a questionmark (always 'UnificationMeta').

newInteractionMetaArg
  :: ArgInfo    -- ^ Relevance of meta.
  -> ArgName    -- ^ Name suggestion for meta.
  -> Comparison -- ^ Check (@CmpLeq@) or infer (@CmpEq@) the type.
  -> Type       -- ^ Type of meta.
  -> TCM (MetaId, Term)  -- ^ The created meta as id and as term.
newInteractionMetaArg :: ArgInfo -> ArgName -> Comparison -> Type -> TCM (MetaId, Term)
newInteractionMetaArg ArgInfo
info ArgName
x Comparison
cmp Type
a = do
  ArgInfo -> TCM (MetaId, Term) -> TCM (MetaId, Term)
forall (tcm :: * -> *) m a.
(MonadTCEnv tcm, LensModality m) =>
m -> tcm a -> tcm a
applyModalityToContext ArgInfo
info (TCM (MetaId, Term) -> TCM (MetaId, Term))
-> TCM (MetaId, Term) -> TCM (MetaId, Term)
forall a b. (a -> b) -> a -> b
$
    RunMetaOccursCheck
-> ArgName -> Comparison -> Type -> TCM (MetaId, Term)
forall (m :: * -> *).
MonadMetaSolver m =>
RunMetaOccursCheck
-> ArgName -> Comparison -> Type -> m (MetaId, Term)
newNamedValueMeta' RunMetaOccursCheck
RunMetaOccursCheck (ArgName -> ArgName
argNameToString ArgName
x) Comparison
cmp Type
a

---------------------------------------------------------------------------

-- | Possible results of 'insertImplicit'.
data ImplicitInsertion
      = ImpInsert [Dom ()] -- ^ Success: this many implicits have to be inserted (list can be empty).
      | BadImplicits       -- ^ Error: hidden argument where there should have been a non-hidden argument.
      | NoSuchName ArgName -- ^ Error: bad named argument.
  deriving (Int -> ImplicitInsertion -> ArgName -> ArgName
[ImplicitInsertion] -> ArgName -> ArgName
ImplicitInsertion -> ArgName
(Int -> ImplicitInsertion -> ArgName -> ArgName)
-> (ImplicitInsertion -> ArgName)
-> ([ImplicitInsertion] -> ArgName -> ArgName)
-> Show ImplicitInsertion
forall a.
(Int -> a -> ArgName -> ArgName)
-> (a -> ArgName) -> ([a] -> ArgName -> ArgName) -> Show a
$cshowsPrec :: Int -> ImplicitInsertion -> ArgName -> ArgName
showsPrec :: Int -> ImplicitInsertion -> ArgName -> ArgName
$cshow :: ImplicitInsertion -> ArgName
show :: ImplicitInsertion -> ArgName
$cshowList :: [ImplicitInsertion] -> ArgName -> ArgName
showList :: [ImplicitInsertion] -> ArgName -> ArgName
Show)

pattern NoInsertNeeded :: ImplicitInsertion
pattern $mNoInsertNeeded :: forall {r}. ImplicitInsertion -> ((# #) -> r) -> ((# #) -> r) -> r
$bNoInsertNeeded :: ImplicitInsertion
NoInsertNeeded = ImpInsert []

-- | If the next given argument is @a@ and the expected arguments are @ts@
--   @insertImplicit' a ts@ returns the prefix of @ts@ that precedes @a@.
--
--   If @a@ is named but this name does not appear in @ts@, the 'NoSuchName' exception is thrown.
--
insertImplicit
  :: NamedArg e  -- ^ Next given argument @a@.
  -> [Dom a]     -- ^ Expected arguments @ts@.
  -> ImplicitInsertion
insertImplicit :: forall e a. NamedArg e -> [Dom a] -> ImplicitInsertion
insertImplicit NamedArg e
a [Dom a]
doms = NamedArg e -> [Dom ArgName] -> ImplicitInsertion
forall e. NamedArg e -> [Dom ArgName] -> ImplicitInsertion
insertImplicit' NamedArg e
a ([Dom ArgName] -> ImplicitInsertion)
-> [Dom ArgName] -> ImplicitInsertion
forall a b. (a -> b) -> a -> b
$
  [Dom a] -> (Dom a -> Dom ArgName) -> [Dom ArgName]
forall (m :: * -> *) a b. Functor m => m a -> (a -> b) -> m b
for [Dom a]
doms ((Dom a -> Dom ArgName) -> [Dom ArgName])
-> (Dom a -> Dom ArgName) -> [Dom ArgName]
forall a b. (a -> b) -> a -> b
$ \ Dom a
dom ->
    Dom a
dom Dom a -> ArgName -> Dom ArgName
forall (f :: * -> *) a b. Functor f => f a -> b -> f b
$> ArgName -> Dom a -> ArgName
forall a.
(LensNamed a, NameOf a ~ NamedName) =>
ArgName -> a -> ArgName
bareNameWithDefault ArgName
"_" Dom a
dom

-- | If the next given argument is @a@ and the expected arguments are @ts@
--   @insertImplicit' a ts@ returns the prefix of @ts@ that precedes @a@.
--
--   If @a@ is named but this name does not appear in @ts@, the 'NoSuchName' exception is thrown.
--
insertImplicit'
  :: NamedArg e     -- ^ Next given argument @a@.
  -> [Dom ArgName]  -- ^ Expected arguments @ts@.
  -> ImplicitInsertion
insertImplicit' :: forall e. NamedArg e -> [Dom ArgName] -> ImplicitInsertion
insertImplicit' NamedArg e
_ [] = ImplicitInsertion
BadImplicits
insertImplicit' NamedArg e
a [Dom ArgName]
ts

  -- If @a@ is visible, then take the non-visible prefix of @ts@.
  | NamedArg e -> Bool
forall a. LensHiding a => a -> Bool
visible NamedArg e
a = [Dom ()] -> ImplicitInsertion
ImpInsert ([Dom ()] -> ImplicitInsertion) -> [Dom ()] -> ImplicitInsertion
forall a b. (a -> b) -> a -> b
$ (Dom () -> Bool) -> [Dom ()] -> [Dom ()]
forall a. (a -> Bool) -> [a] -> [a]
takeWhile Dom () -> Bool
forall a. LensHiding a => a -> Bool
notVisible ([Dom ()] -> [Dom ()]) -> [Dom ()] -> [Dom ()]
forall a b. (a -> b) -> a -> b
$ (Dom ArgName -> Dom ()) -> [Dom ArgName] -> [Dom ()]
forall a b. (a -> b) -> [a] -> [b]
map Dom ArgName -> Dom ()
forall (f :: * -> *) a. Functor f => f a -> f ()
void [Dom ArgName]
ts

  -- If @a@ is named, take prefix of @ts@ until the name of @a@ (with correct hiding).
  -- If the name is not found, throw exception 'NoSuchName'.
  | Just ArgName
x <- NamedArg e -> Maybe ArgName
forall a. (LensNamed a, NameOf a ~ NamedName) => a -> Maybe ArgName
bareNameOf NamedArg e
a = ImplicitInsertion
-> ([Dom ()] -> ImplicitInsertion)
-> Maybe [Dom ()]
-> ImplicitInsertion
forall b a. b -> (a -> b) -> Maybe a -> b
maybe (ArgName -> ImplicitInsertion
NoSuchName ArgName
x) [Dom ()] -> ImplicitInsertion
ImpInsert (Maybe [Dom ()] -> ImplicitInsertion)
-> Maybe [Dom ()] -> ImplicitInsertion
forall a b. (a -> b) -> a -> b
$
      (Dom ArgName -> Bool) -> [Dom ArgName] -> Maybe [Dom ()]
takeHiddenUntil (\ Dom ArgName
t -> ArgName
x ArgName -> ArgName -> Bool
forall a. Eq a => a -> a -> Bool
== Dom ArgName -> ArgName
forall t e. Dom' t e -> e
unDom Dom ArgName
t Bool -> Bool -> Bool
&& NamedArg e -> Dom ArgName -> Bool
forall a b. (LensHiding a, LensHiding b) => a -> b -> Bool
sameHiding NamedArg e
a Dom ArgName
t) [Dom ArgName]
ts

  -- If @a@ is neither visible nor named, take prefix of @ts@ with different hiding than @a@.
  | Bool
otherwise = ImplicitInsertion
-> ([Dom ()] -> ImplicitInsertion)
-> Maybe [Dom ()]
-> ImplicitInsertion
forall b a. b -> (a -> b) -> Maybe a -> b
maybe ImplicitInsertion
BadImplicits [Dom ()] -> ImplicitInsertion
ImpInsert (Maybe [Dom ()] -> ImplicitInsertion)
-> Maybe [Dom ()] -> ImplicitInsertion
forall a b. (a -> b) -> a -> b
$
      (Dom ArgName -> Bool) -> [Dom ArgName] -> Maybe [Dom ()]
takeHiddenUntil (NamedArg e -> Dom ArgName -> Bool
forall a b. (LensHiding a, LensHiding b) => a -> b -> Bool
sameHiding NamedArg e
a) [Dom ArgName]
ts

    where
    -- @takeHiddenUntil p ts@ returns the 'getHiding' of the prefix of @ts@
    -- until @p@ holds or a visible argument is encountered.
    -- If @p@ never holds, 'Nothing' is returned.
    --
    --   Precondition: @p@ should imply @not . visible@.
    takeHiddenUntil :: (Dom ArgName -> Bool) -> [Dom ArgName] -> Maybe [Dom ()]
    takeHiddenUntil :: (Dom ArgName -> Bool) -> [Dom ArgName] -> Maybe [Dom ()]
takeHiddenUntil Dom ArgName -> Bool
p [Dom ArgName]
ts =
      case [Dom ArgName]
ts2 of
        []      -> Maybe [Dom ()]
forall a. Maybe a
Nothing  -- Predicate was never true
        (Dom ArgName
t : [Dom ArgName]
_) -> if Dom ArgName -> Bool
forall a. LensHiding a => a -> Bool
visible Dom ArgName
t then Maybe [Dom ()]
forall a. Maybe a
Nothing else [Dom ()] -> Maybe [Dom ()]
forall a. a -> Maybe a
Just ([Dom ()] -> Maybe [Dom ()]) -> [Dom ()] -> Maybe [Dom ()]
forall a b. (a -> b) -> a -> b
$ (Dom ArgName -> Dom ()) -> [Dom ArgName] -> [Dom ()]
forall a b. (a -> b) -> [a] -> [b]
map Dom ArgName -> Dom ()
forall (f :: * -> *) a. Functor f => f a -> f ()
void [Dom ArgName]
ts1
      where
      ([Dom ArgName]
ts1, [Dom ArgName]
ts2) = (Dom ArgName -> Bool)
-> [Dom ArgName] -> ([Dom ArgName], [Dom ArgName])
forall a. (a -> Bool) -> [a] -> ([a], [a])
break (\ Dom ArgName
t -> Dom ArgName -> Bool
p Dom ArgName
t Bool -> Bool -> Bool
|| Dom ArgName -> Bool
forall a. LensHiding a => a -> Bool
visible Dom ArgName
t) [Dom ArgName]
ts