    {-# LANGUAGE NondecreasingIndentation #-}

    -- | Pattern matcher used in the reducer for clauses that
    --   have not been compiled to case trees yet.

    module Agda.TypeChecking.Patterns.Match where

    import Prelude hiding (null)

    import Control.Monad
    import Data.IntMap (IntMap)
    import qualified Data.IntMap as IntMap

    import Agda.Syntax.Common
    import Agda.Syntax.Internal
    import Agda.Syntax.Internal.Pattern

    import Agda.TypeChecking.Reduce
    import Agda.TypeChecking.Reduce.Monad
    import Agda.TypeChecking.Substitute
    import Agda.TypeChecking.Monad hiding (constructorForm)
    import Agda.TypeChecking.Pretty
    import Agda.TypeChecking.Records

    import Agda.Utils.Empty
    import Agda.Utils.Functor (for, ($>), (<&>))
    import Agda.Utils.Maybe
    import Agda.Utils.Null
    import Agda.Utils.Singleton
    import Agda.Utils.Size
    import Agda.Utils.Tuple

    import Agda.Utils.Impossible

    -- | If matching is inconclusive (@DontKnow@) we want to know whether
    --   it is due to a particular meta variable.
    data Match a = Yes Simplification (IntMap (Arg a))
                 | No
                 | DontKnow (Blocked ())
      deriving (forall a b. (a -> b) -> Match a -> Match b)
    -> (forall a b. a -> Match b -> Match a) -> Functor Match
    forall a b. a -> Match b -> Match a
    forall a b. (a -> b) -> Match a -> Match b
    forall (f :: * -> *).
    (forall a b. (a -> b) -> f a -> f b)
    -> (forall a b. a -> f b -> f a) -> Functor f
    <$ :: forall a b. a -> Match b -> Match a
    $c<$ :: forall a b. a -> Match b -> Match a
    fmap :: forall a b. (a -> b) -> Match a -> Match b
    $cfmap :: forall a b. (a -> b) -> Match a -> Match b
    Functor

    instance Null (Match a) where
      empty :: Match a
    empty = Simplification -> IntMap (Arg a) -> Match a
    forall a. Simplification -> IntMap (Arg a) -> Match a
    Yes Simplification
    forall a. Null a => a
    empty IntMap (Arg a)
    forall a. Null a => a
    empty
      null :: Match a -> Bool
    null (Yes Simplification
    simpl IntMap (Arg a)
    as) = Simplification -> Bool
    forall a. Null a => a -> Bool
    null Simplification
    simpl Bool -> Bool -> Bool
    && IntMap (Arg a) -> Bool
    forall a. Null a => a -> Bool
    null IntMap (Arg a)
    as
      null Match a
    _              = Bool
    False

    matchedArgs :: Empty -> Int -> IntMap (Arg a) -> [Arg a]
    matchedArgs :: forall a. Empty -> Int -> IntMap (Arg a) -> [Arg a]
    matchedArgs Empty
    err Int
    n IntMap (Arg a)
    vs = (Maybe (Arg a) -> Arg a) -> [Maybe (Arg a)] -> [Arg a]
    forall a b. (a -> b) -> [a] -> [b]
    map (Arg a -> Maybe (Arg a) -> Arg a
    forall a. a -> Maybe a -> a
    fromMaybe (Empty -> Arg a
    forall a. Empty -> a
    absurd Empty
    err)) ([Maybe (Arg a)] -> [Arg a]) -> [Maybe (Arg a)] -> [Arg a]
    forall a b. (a -> b) -> a -> b
    $ Int -> IntMap (Arg a) -> [Maybe (Arg a)]
    forall a. Int -> IntMap (Arg a) -> [Maybe (Arg a)]
    matchedArgs' Int
    n IntMap (Arg a)
    vs

    matchedArgs' :: Int -> IntMap (Arg a) -> [Maybe (Arg a)]
    matchedArgs' :: forall a. Int -> IntMap (Arg a) -> [Maybe (Arg a)]
    matchedArgs' Int
    n IntMap (Arg a)
    vs = (Int -> Maybe (Arg a)) -> [Int] -> [Maybe (Arg a)]
    forall a b. (a -> b) -> [a] -> [b]
    map Int -> Maybe (Arg a)
    get [Int
    0 .. Int
    n Int -> Int -> Int
    forall a. Num a => a -> a -> a
    - Int
    1]
      where
        get :: Int -> Maybe (Arg a)
    get Int
    k = Int -> IntMap (Arg a) -> Maybe (Arg a)
    forall a. Int -> IntMap a -> Maybe a
    IntMap.lookup Int
    k IntMap (Arg a)
    vs

    -- | Builds a proper substitution from an IntMap produced by match(Co)patterns
    buildSubstitution :: (DeBruijn a)
                      => Impossible -> Int -> IntMap (Arg a) -> Substitution' a
    buildSubstitution :: forall a.
    DeBruijn a =>
    Impossible -> Int -> IntMap (Arg a) -> Substitution' a
    buildSubstitution Impossible
    err Int
    n IntMap (Arg a)
    vs = (Maybe (Arg a) -> Substitution' a -> Substitution' a)
    -> Substitution' a -> [Maybe (Arg a)] -> Substitution' a
    forall (t :: * -> *) a b.
    Foldable t =>
    (a -> b -> b) -> b -> t a -> b
    foldr Maybe (Arg a) -> Substitution' a -> Substitution' a
    cons Substitution' a
    forall a. Substitution' a
    idS ([Maybe (Arg a)] -> Substitution' a)
    -> [Maybe (Arg a)] -> Substitution' a
    forall a b. (a -> b) -> a -> b
    $ Int -> IntMap (Arg a) -> [Maybe (Arg a)]
    forall a. Int -> IntMap (Arg a) -> [Maybe (Arg a)]
    matchedArgs' Int
    n IntMap (Arg a)
    vs
      where cons :: Maybe (Arg a) -> Substitution' a -> Substitution' a
    cons Maybe (Arg a)
    Nothing  = Impossible -> Substitution' a -> Substitution' a
    forall a. Impossible -> Substitution' a -> Substitution' a
    Strengthen Impossible
    err
            cons (Just Arg a
    v) = a -> Substitution' a -> Substitution' a
    forall a. DeBruijn a => a -> Substitution' a -> Substitution' a
    consS (Arg a -> a
    forall e. Arg e -> e
    unArg Arg a
    v)

    instance Semigroup (Match a) where
        -- @NotBlocked (StuckOn e)@ means blocked by a variable.
        -- In this case, no instantiation of meta-variables will make progress.
        DontKnow Blocked ()
    b <> :: Match a -> Match a -> Match a
    <> DontKnow Blocked ()
    b'      = Blocked () -> Match a
    forall a. Blocked () -> Match a
    DontKnow (Blocked () -> Match a) -> Blocked () -> Match a
    forall a b. (a -> b) -> a -> b
    $ Blocked ()
    b Blocked () -> Blocked () -> Blocked ()
    forall a. Semigroup a => a -> a -> a
    <> Blocked ()
    b'
        DontKnow Blocked ()
    m <> Match a
    _                = Blocked () -> Match a
    forall a. Blocked () -> Match a
    DontKnow Blocked ()
    m
        Match a
    _          <> DontKnow Blocked ()
    m       = Blocked () -> Match a
    forall a. Blocked () -> Match a
    DontKnow Blocked ()
    m
        -- One could imagine DontKnow _ <> No = No, but would break the
        -- equivalence to case-trees (Issue 2964).
        Match a
    No         <> Match a
    _                = Match a
    forall a. Match a
    No
        Match a
    _          <> Match a
    No               = Match a
    forall a. Match a
    No
        Yes Simplification
    s IntMap (Arg a)
    us   <> Yes Simplification
    s' IntMap (Arg a)
    vs        = Simplification -> IntMap (Arg a) -> Match a
    forall a. Simplification -> IntMap (Arg a) -> Match a
    Yes (Simplification
    s Simplification -> Simplification -> Simplification
    forall a. Semigroup a => a -> a -> a
    <> Simplification
    s') (IntMap (Arg a)
    us IntMap (Arg a) -> IntMap (Arg a) -> IntMap (Arg a)
    forall a. Semigroup a => a -> a -> a
    <> IntMap (Arg a)
    vs)

    instance Monoid (Match a) where
        mempty :: Match a
    mempty = Match a
    forall a. Null a => a
    empty
        mappend :: Match a -> Match a -> Match a
    mappend = Match a -> Match a -> Match a
    forall a. Semigroup a => a -> a -> a
    (<>)

    -- | Instead of 'zipWithM', we need to use this lazy version
    --   of combining pattern matching computations.

    -- Andreas, 2014-05-08, see Issue 1124:
    --
    -- Due to a bug in TypeChecking.Patterns.Match
    -- a failed match of (C n b) against (C O unit)
    -- turned into (C n unit).
    -- This was because all patterns were matched in
    -- parallel, and evaluations of successfull matches
    -- (and a record constructor like unit can always
    -- be successfully matched) were returned, leading
    -- to a reassembly of (C n b) as (C n unit) which is
    -- illtyped.

    -- Now patterns are matched left to right and
    -- upon failure, no further matching is performed.

    foldMatch
      :: forall m p v . (IsProjP p, MonadMatch m)
      => (p -> v -> m (Match Term, v))
      -> [p] -> [v] -> m (Match Term, [v])
    foldMatch :: forall (m :: * -> *) p v.
    (IsProjP p, MonadMatch m) =>
    (p -> v -> m (Match Term, v)) -> [p] -> [v] -> m (Match Term, [v])
    foldMatch p -> v -> m (Match Term, v)
    match = [p] -> [v] -> m (Match Term, [v])
    loop where
      loop :: [p] -> [v] -> m (Match Term, [v])
      loop :: [p] -> [v] -> m (Match Term, [v])
    loop [p]
    ps0 [v]
    vs0 = do
        case ([p]
    ps0, [v]
    vs0) of
          ([], []) -> (Match Term, [v]) -> m (Match Term, [v])
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match Term
    forall a. Null a => a
    empty, [])
          (p
    p : [p]
    ps, v
    v : [v]
    vs) -> do
            (Match Term
    r, v
    v') <- p -> v -> m (Match Term, v)
    match p
    p v
    v
            case Match Term
    r of
              Match Term
    No | Just{} <- p -> Maybe (ProjOrigin, AmbiguousQName)
    forall a. IsProjP a => a -> Maybe (ProjOrigin, AmbiguousQName)
    isProjP p
    p -> (Match Term, [v]) -> m (Match Term, [v])
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match Term
    forall a. Match a
    No, v
    v' v -> [v] -> [v]
    forall a. a -> [a] -> [a]
    : [v]
    vs)
              Match Term
    No -> do
                -- Issue 2964: Even when the first pattern doesn't match we should
                -- continue to the next patterns (and potentially block on them)
                -- because the splitting order in the case tree may not be
                -- left-to-right.
                (Match Term
    r', [v]
    _vs') <- [p] -> [v] -> m (Match Term, [v])
    loop [p]
    ps [v]
    vs
                -- Issue 2968: do not use vs' here, because it might
                -- contain ill-typed terms due to eta-expansion at wrong
                -- type.
                (Match Term, [v]) -> m (Match Term, [v])
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match Term
    r Match Term -> Match Term -> Match Term
    forall a. Semigroup a => a -> a -> a
    <> Match Term
    r', v
    v' v -> [v] -> [v]
    forall a. a -> [a] -> [a]
    : [v]
    vs)
              DontKnow Blocked ()
    m -> (Match Term, [v]) -> m (Match Term, [v])
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Blocked () -> Match Term
    forall a. Blocked () -> Match a
    DontKnow Blocked ()
    m, v
    v' v -> [v] -> [v]
    forall a. a -> [a] -> [a]
    : [v]
    vs)
              Yes{} -> do
                (Match Term
    r', [v]
    vs') <- [p] -> [v] -> m (Match Term, [v])
    loop [p]
    ps [v]
    vs
                (Match Term, [v]) -> m (Match Term, [v])
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match Term
    r Match Term -> Match Term -> Match Term
    forall a. Semigroup a => a -> a -> a
    <> Match Term
    r', v
    v' v -> [v] -> [v]
    forall a. a -> [a] -> [a]
    : [v]
    vs')
          ([p], [v])
    _ -> m (Match Term, [v])
    forall a. HasCallStack => a
    __IMPOSSIBLE__

    -- TODO refactor matchPattern* to work with Elim instead.
    mergeElim :: Elim -> Arg Term -> Elim
    mergeElim :: Elim -> Arg Term -> Elim
    mergeElim Apply{} Arg Term
    arg = Arg Term -> Elim
    forall a. Arg a -> Elim' a
    Apply Arg Term
    arg
    mergeElim (IApply Term
    x Term
    y Term
    _) Arg Term
    arg = Term -> Term -> Term -> Elim
    forall a. a -> a -> a -> Elim' a
    IApply Term
    x Term
    y (Arg Term -> Term
    forall e. Arg e -> e
    unArg Arg Term
    arg)
    mergeElim Proj{} Arg Term
    _ = Elim
    forall a. HasCallStack => a
    __IMPOSSIBLE__

    mergeElims :: [Elim] -> [Arg Term] -> [Elim]
    mergeElims :: [Elim] -> [Arg Term] -> [Elim]
    mergeElims = (Elim -> Arg Term -> Elim) -> [Elim] -> [Arg Term] -> [Elim]
    forall a b c. (a -> b -> c) -> [a] -> [b] -> [c]
    zipWith Elim -> Arg Term -> Elim
    mergeElim

    type MonadMatch m = PureTCM m

    -- | @matchCopatterns ps es@ matches spine @es@ against copattern spine @ps@.
    --
    --   Returns 'Yes' and a substitution for the pattern variables
    --   (in form of IntMap Term) if matching was successful.
    --
    --   Returns 'No' if there was a constructor or projection mismatch.
    --
    --   Returns 'DontKnow' if an argument could not be evaluated to
    --   constructor form because of a blocking meta variable.
    --
    --   In any case, also returns spine @es@ in reduced form
    --   (with all the weak head reductions performed that were necessary
    --   to come to a decision).
    matchCopatterns :: MonadMatch m
                    => [NamedArg DeBruijnPattern]
                    -> [Elim]
                    -> m (Match Term, [Elim])
    matchCopatterns :: forall (m :: * -> *).
    MonadMatch m =>
    [NamedArg DeBruijnPattern] -> [Elim] -> m (Match Term, [Elim])
    matchCopatterns [NamedArg DeBruijnPattern]
    ps [Elim]
    vs = do
      VerboseKey
    -> Int
    -> TCMT IO Doc
    -> m (Match Term, [Elim])
    -> m (Match Term, [Elim])
    forall (m :: * -> *) a.
    MonadDebug m =>
    VerboseKey -> Int -> TCMT IO Doc -> m a -> m a
    traceSDoc VerboseKey
    "tc.match" Int
    50
        ([TCMT IO Doc] -> TCMT IO Doc
    forall (m :: * -> *) (t :: * -> *).
    (Applicative m, Foldable t) =>
    t (m Doc) -> m Doc
    vcat [ TCMT IO Doc
    "matchCopatterns"
              , 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
    "ps =" TCMT IO Doc -> TCMT IO Doc -> TCMT IO Doc
    forall (m :: * -> *). Applicative m => m Doc -> m Doc -> m Doc
    <+> [TCMT IO Doc] -> TCMT IO Doc
    forall (m :: * -> *) (t :: * -> *).
    (Applicative m, Foldable t) =>
    t (m Doc) -> m Doc
    fsep (TCMT IO Doc -> [TCMT IO Doc] -> [TCMT IO Doc]
    forall (m :: * -> *) (t :: * -> *).
    (Applicative m, Semigroup (m Doc), Foldable t) =>
    m Doc -> t (m Doc) -> [m Doc]
    punctuate TCMT IO Doc
    forall (m :: * -> *). Applicative m => m Doc
    comma ([TCMT IO Doc] -> [TCMT IO Doc]) -> [TCMT IO Doc] -> [TCMT IO Doc]
    forall a b. (a -> b) -> a -> b
    $ (NamedArg DeBruijnPattern -> TCMT IO Doc)
    -> [NamedArg DeBruijnPattern] -> [TCMT IO Doc]
    forall a b. (a -> b) -> [a] -> [b]
    map (DeBruijnPattern -> TCMT IO Doc
    forall a (m :: * -> *). (PrettyTCM a, MonadPretty m) => a -> m Doc
    prettyTCM (DeBruijnPattern -> TCMT IO Doc)
    -> (NamedArg DeBruijnPattern -> DeBruijnPattern)
    -> NamedArg DeBruijnPattern
    -> TCMT IO Doc
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . NamedArg DeBruijnPattern -> DeBruijnPattern
    forall a. NamedArg a -> a
    namedArg) [NamedArg DeBruijnPattern]
    ps)
              , 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
    "vs =" TCMT IO Doc -> TCMT IO Doc -> TCMT IO Doc
    forall (m :: * -> *). Applicative m => m Doc -> m Doc -> m Doc
    <+> [TCMT IO Doc] -> TCMT IO Doc
    forall (m :: * -> *) (t :: * -> *).
    (Applicative m, Foldable t) =>
    t (m Doc) -> m Doc
    fsep (TCMT IO Doc -> [TCMT IO Doc] -> [TCMT IO Doc]
    forall (m :: * -> *) (t :: * -> *).
    (Applicative m, Semigroup (m Doc), Foldable t) =>
    m Doc -> t (m Doc) -> [m Doc]
    punctuate TCMT IO Doc
    forall (m :: * -> *). Applicative m => m Doc
    comma ([TCMT IO Doc] -> [TCMT IO Doc]) -> [TCMT IO Doc] -> [TCMT IO Doc]
    forall a b. (a -> b) -> a -> b
    $ (Elim -> TCMT IO Doc) -> [Elim] -> [TCMT IO Doc]
    forall a b. (a -> b) -> [a] -> [b]
    map Elim -> TCMT IO Doc
    forall a (m :: * -> *). (PrettyTCM a, MonadPretty m) => a -> m Doc
    prettyTCM [Elim]
    vs)
              ]) (m (Match Term, [Elim]) -> m (Match Term, [Elim]))
    -> m (Match Term, [Elim]) -> m (Match Term, [Elim])
    forall a b. (a -> b) -> a -> b
    $ do
      -- Buggy, see issue 1124:
      -- mapFst mconcat . unzip <$> zipWithM' (matchCopattern . namedArg) ps vs
      (NamedArg DeBruijnPattern -> Elim -> m (Match Term, Elim))
    -> [NamedArg DeBruijnPattern] -> [Elim] -> m (Match Term, [Elim])
    forall (m :: * -> *) p v.
    (IsProjP p, MonadMatch m) =>
    (p -> v -> m (Match Term, v)) -> [p] -> [v] -> m (Match Term, [v])
    foldMatch (DeBruijnPattern -> Elim -> m (Match Term, Elim)
    forall (m :: * -> *).
    MonadMatch m =>
    DeBruijnPattern -> Elim -> m (Match Term, Elim)
    matchCopattern (DeBruijnPattern -> Elim -> m (Match Term, Elim))
    -> (NamedArg DeBruijnPattern -> DeBruijnPattern)
    -> NamedArg DeBruijnPattern
    -> Elim
    -> m (Match Term, Elim)
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . NamedArg DeBruijnPattern -> DeBruijnPattern
    forall a. NamedArg a -> a
    namedArg) [NamedArg DeBruijnPattern]
    ps [Elim]
    vs

    -- | Match a single copattern.
    matchCopattern :: MonadMatch m
                   => DeBruijnPattern
                   -> Elim
                   -> m (Match Term, Elim)
    matchCopattern :: forall (m :: * -> *).
    MonadMatch m =>
    DeBruijnPattern -> Elim -> m (Match Term, Elim)
    matchCopattern pat :: DeBruijnPattern
    pat@ProjP{} elim :: Elim
    elim@(Proj ProjOrigin
    _ QName
    q) = do
      QName
    p <- DeBruijnPattern -> m DeBruijnPattern
    forall a (m :: * -> *).
    (NormaliseProjP a, HasConstInfo m) =>
    a -> m a
    normaliseProjP DeBruijnPattern
    pat m DeBruijnPattern -> (DeBruijnPattern -> QName) -> m QName
    forall (m :: * -> *) a b. Functor m => m a -> (a -> b) -> m b
    <&> \case
             ProjP ProjOrigin
    _ QName
    p -> QName
    p
             DeBruijnPattern
    _         -> QName
    forall a. HasCallStack => a
    __IMPOSSIBLE__
      QName
    q       <- QName -> m QName
    forall (m :: * -> *). HasConstInfo m => QName -> m QName
    getOriginalProjection QName
    q
      (Match Term, Elim) -> m (Match Term, Elim)
    forall (m :: * -> *) a. Monad m => a -> m a
    return ((Match Term, Elim) -> m (Match Term, Elim))
    -> (Match Term, Elim) -> m (Match Term, Elim)
    forall a b. (a -> b) -> a -> b
    $ if QName
    p QName -> QName -> Bool
    forall a. Eq a => a -> a -> Bool
    == QName
    q then (Simplification -> IntMap (Arg Term) -> Match Term
    forall a. Simplification -> IntMap (Arg a) -> Match a
    Yes Simplification
    YesSimplification IntMap (Arg Term)
    forall a. Null a => a
    empty, Elim
    elim)
                         else (Match Term
    forall a. Match a
    No,                          Elim
    elim)
    -- The following two cases are not impossible, see #2964
    matchCopattern ProjP{} elim :: Elim
    elim@Apply{}   = (Match Term, Elim) -> m (Match Term, Elim)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match Term
    forall a. Match a
    No , Elim
    elim)
    matchCopattern DeBruijnPattern
    _       elim :: Elim
    elim@Proj{}    = (Match Term, Elim) -> m (Match Term, Elim)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match Term
    forall a. Match a
    No , Elim
    elim)
    matchCopattern DeBruijnPattern
    p       (Apply Arg Term
    v) = (Arg Term -> Elim) -> (Match Term, Arg Term) -> (Match Term, Elim)
    forall b d a. (b -> d) -> (a, b) -> (a, d)
    mapSnd Arg Term -> Elim
    forall a. Arg a -> Elim' a
    Apply ((Match Term, Arg Term) -> (Match Term, Elim))
    -> m (Match Term, Arg Term) -> m (Match Term, Elim)
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    <$> DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term)
    forall (m :: * -> *).
    MonadMatch m =>
    DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term)
    matchPattern DeBruijnPattern
    p Arg Term
    v
    matchCopattern DeBruijnPattern
    p       e :: Elim
    e@(IApply Term
    x Term
    y Term
    r) = (Arg Term -> Elim) -> (Match Term, Arg Term) -> (Match Term, Elim)
    forall b d a. (b -> d) -> (a, b) -> (a, d)
    mapSnd (Elim -> Arg Term -> Elim
    mergeElim Elim
    e) ((Match Term, Arg Term) -> (Match Term, Elim))
    -> m (Match Term, Arg Term) -> m (Match Term, Elim)
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    <$> DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term)
    forall (m :: * -> *).
    MonadMatch m =>
    DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term)
    matchPattern DeBruijnPattern
    p (Term -> Arg Term
    forall a. a -> Arg a
    defaultArg Term
    r)

    matchPatterns :: MonadMatch m
                  => [NamedArg DeBruijnPattern]
                  -> [Arg Term]
                  -> m (Match Term, [Arg Term])
    matchPatterns :: forall (m :: * -> *).
    MonadMatch m =>
    [NamedArg DeBruijnPattern]
    -> [Arg Term] -> m (Match Term, [Arg Term])
    matchPatterns [NamedArg DeBruijnPattern]
    ps [Arg Term]
    vs = do
      VerboseKey -> Int -> TCMT IO Doc -> m ()
    forall (m :: * -> *).
    MonadDebug m =>
    VerboseKey -> Int -> TCMT IO Doc -> m ()
    reportSDoc VerboseKey
    "tc.match" Int
    20 (TCMT IO Doc -> m ()) -> TCMT IO Doc -> m ()
    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
    "matchPatterns"
              , 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
    "ps =" TCMT IO Doc -> TCMT IO Doc -> TCMT IO Doc
    forall (m :: * -> *). Applicative m => m Doc -> m Doc -> m Doc
    <+> [NamedArg DeBruijnPattern] -> TCMT IO Doc
    forall (m :: * -> *).
    MonadPretty m =>
    [NamedArg DeBruijnPattern] -> m Doc
    prettyTCMPatternList [NamedArg DeBruijnPattern]
    ps
              , 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
    "vs =" TCMT IO Doc -> TCMT IO Doc -> TCMT IO Doc
    forall (m :: * -> *). Applicative m => m Doc -> m Doc -> m Doc
    <+> [TCMT IO Doc] -> TCMT IO Doc
    forall (m :: * -> *) (t :: * -> *).
    (Applicative m, Foldable t) =>
    t (m Doc) -> m Doc
    fsep (TCMT IO Doc -> [TCMT IO Doc] -> [TCMT IO Doc]
    forall (m :: * -> *) (t :: * -> *).
    (Applicative m, Semigroup (m Doc), Foldable t) =>
    m Doc -> t (m Doc) -> [m Doc]
    punctuate TCMT IO Doc
    forall (m :: * -> *). Applicative m => m Doc
    comma ([TCMT IO Doc] -> [TCMT IO Doc]) -> [TCMT IO Doc] -> [TCMT IO Doc]
    forall a b. (a -> b) -> a -> b
    $ (Arg Term -> TCMT IO Doc) -> [Arg Term] -> [TCMT IO Doc]
    forall a b. (a -> b) -> [a] -> [b]
    map Arg Term -> TCMT IO Doc
    forall a (m :: * -> *). (PrettyTCM a, MonadPretty m) => a -> m Doc
    prettyTCM [Arg Term]
    vs)
              ]

      VerboseKey
    -> Int
    -> TCMT IO Doc
    -> m (Match Term, [Arg Term])
    -> m (Match Term, [Arg Term])
    forall (m :: * -> *) a.
    MonadDebug m =>
    VerboseKey -> Int -> TCMT IO Doc -> m a -> m a
    traceSDoc VerboseKey
    "tc.match" Int
    50
        ([TCMT IO Doc] -> TCMT IO Doc
    forall (m :: * -> *) (t :: * -> *).
    (Applicative m, Foldable t) =>
    t (m Doc) -> m Doc
    vcat [ TCMT IO Doc
    "matchPatterns"
              , 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
    "ps =" TCMT IO Doc -> TCMT IO Doc -> TCMT IO Doc
    forall (m :: * -> *). Applicative m => m Doc -> m Doc -> m Doc
    <+> [TCMT IO Doc] -> TCMT IO Doc
    forall (m :: * -> *) (t :: * -> *).
    (Applicative m, Foldable t) =>
    t (m Doc) -> m Doc
    fsep (TCMT IO Doc -> [TCMT IO Doc] -> [TCMT IO Doc]
    forall (m :: * -> *) (t :: * -> *).
    (Applicative m, Semigroup (m Doc), Foldable t) =>
    m Doc -> t (m Doc) -> [m Doc]
    punctuate TCMT IO Doc
    forall (m :: * -> *). Applicative m => m Doc
    comma ([TCMT IO Doc] -> [TCMT IO Doc]) -> [TCMT IO Doc] -> [TCMT IO Doc]
    forall a b. (a -> b) -> a -> b
    $ (NamedArg DeBruijnPattern -> TCMT IO Doc)
    -> [NamedArg DeBruijnPattern] -> [TCMT IO Doc]
    forall a b. (a -> b) -> [a] -> [b]
    map (VerboseKey -> TCMT IO Doc
    forall (m :: * -> *). Applicative m => VerboseKey -> m Doc
    text (VerboseKey -> TCMT IO Doc)
    -> (NamedArg DeBruijnPattern -> VerboseKey)
    -> NamedArg DeBruijnPattern
    -> TCMT IO Doc
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . NamedArg DeBruijnPattern -> VerboseKey
    forall a. Show a => a -> VerboseKey
    show) [NamedArg DeBruijnPattern]
    ps)
              , 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
    "vs =" TCMT IO Doc -> TCMT IO Doc -> TCMT IO Doc
    forall (m :: * -> *). Applicative m => m Doc -> m Doc -> m Doc
    <+> [TCMT IO Doc] -> TCMT IO Doc
    forall (m :: * -> *) (t :: * -> *).
    (Applicative m, Foldable t) =>
    t (m Doc) -> m Doc
    fsep (TCMT IO Doc -> [TCMT IO Doc] -> [TCMT IO Doc]
    forall (m :: * -> *) (t :: * -> *).
    (Applicative m, Semigroup (m Doc), Foldable t) =>
    m Doc -> t (m Doc) -> [m Doc]
    punctuate TCMT IO Doc
    forall (m :: * -> *). Applicative m => m Doc
    comma ([TCMT IO Doc] -> [TCMT IO Doc]) -> [TCMT IO Doc] -> [TCMT IO Doc]
    forall a b. (a -> b) -> a -> b
    $ (Arg Term -> TCMT IO Doc) -> [Arg Term] -> [TCMT IO Doc]
    forall a b. (a -> b) -> [a] -> [b]
    map Arg Term -> TCMT IO Doc
    forall a (m :: * -> *). (PrettyTCM a, MonadPretty m) => a -> m Doc
    prettyTCM [Arg Term]
    vs)
              ]) (m (Match Term, [Arg Term]) -> m (Match Term, [Arg Term]))
    -> m (Match Term, [Arg Term]) -> m (Match Term, [Arg Term])
    forall a b. (a -> b) -> a -> b
    $ do
      -- Buggy, see issue 1124:
      -- (ms,vs) <- unzip <$> zipWithM' (matchPattern . namedArg) ps vs
      -- return (mconcat ms, vs)
      (NamedArg DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term))
    -> [NamedArg DeBruijnPattern]
    -> [Arg Term]
    -> m (Match Term, [Arg Term])
    forall (m :: * -> *) p v.
    (IsProjP p, MonadMatch m) =>
    (p -> v -> m (Match Term, v)) -> [p] -> [v] -> m (Match Term, [v])
    foldMatch (DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term)
    forall (m :: * -> *).
    MonadMatch m =>
    DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term)
    matchPattern (DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term))
    -> (NamedArg DeBruijnPattern -> DeBruijnPattern)
    -> NamedArg DeBruijnPattern
    -> Arg Term
    -> m (Match Term, Arg Term)
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . NamedArg DeBruijnPattern -> DeBruijnPattern
    forall a. NamedArg a -> a
    namedArg) [NamedArg DeBruijnPattern]
    ps [Arg Term]
    vs

    -- | Match a single pattern.
    matchPattern :: MonadMatch m
                 => DeBruijnPattern
                 -> Arg Term
                 -> m (Match Term, Arg Term)
    matchPattern :: forall (m :: * -> *).
    MonadMatch m =>
    DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term)
    matchPattern DeBruijnPattern
    p Arg Term
    u = case (DeBruijnPattern
    p, Arg Term
    u) of
      (ProjP{}, Arg Term
    _            ) -> m (Match Term, Arg Term)
    forall a. HasCallStack => a
    __IMPOSSIBLE__
      (IApplyP PatternInfo
    _ Term
    _ Term
    _ DBPatVar
    x , Arg Term
    arg ) -> (Match Term, Arg Term) -> m (Match Term, Arg Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Simplification -> IntMap (Arg Term) -> Match Term
    forall a. Simplification -> IntMap (Arg a) -> Match a
    Yes Simplification
    NoSimplification IntMap (Arg Term)
    entry, Arg Term
    arg)
        where entry :: IntMap (Arg Term)
    entry = (Int, Arg Term) -> IntMap (Arg Term)
    forall el coll. Singleton el coll => el -> coll
    singleton (DBPatVar -> Int
    dbPatVarIndex DBPatVar
    x, Arg Term
    arg)
      (VarP PatternInfo
    _ DBPatVar
    x , Arg Term
    arg          ) -> (Match Term, Arg Term) -> m (Match Term, Arg Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Simplification -> IntMap (Arg Term) -> Match Term
    forall a. Simplification -> IntMap (Arg a) -> Match a
    Yes Simplification
    NoSimplification IntMap (Arg Term)
    entry, Arg Term
    arg)
        where entry :: IntMap (Arg Term)
    entry = (Int, Arg Term) -> IntMap (Arg Term)
    forall el coll. Singleton el coll => el -> coll
    singleton (DBPatVar -> Int
    dbPatVarIndex DBPatVar
    x, Arg Term
    arg)
      (DotP PatternInfo
    _ Term
    _ , arg :: Arg Term
    arg@(Arg ArgInfo
    _ Term
    v)) -> (Match Term, Arg Term) -> m (Match Term, Arg Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Simplification -> IntMap (Arg Term) -> Match Term
    forall a. Simplification -> IntMap (Arg a) -> Match a
    Yes Simplification
    NoSimplification IntMap (Arg Term)
    forall a. Null a => a
    empty, Arg Term
    arg)
      (LitP PatternInfo
    _ Literal
    l , arg :: Arg Term
    arg@(Arg ArgInfo
    _ Term
    v)) -> do
        Blocked Term
    w <- Term -> m (Blocked Term)
    forall a (m :: * -> *).
    (Reduce a, MonadReduce m) =>
    a -> m (Blocked a)
    reduceB Term
    v
        let arg' :: Arg Term
    arg' = Arg Term
    arg Arg Term -> Term -> Arg Term
    forall (f :: * -> *) a b. Functor f => f a -> b -> f b
    $> Blocked Term -> Term
    forall t a. Blocked' t a -> a
    ignoreBlocking Blocked Term
    w
        case Blocked Term
    w of
          NotBlocked NotBlocked' Term
    _ (Lit Literal
    l')
              | Literal
    l Literal -> Literal -> Bool
    forall a. Eq a => a -> a -> Bool
    == Literal
    l'            -> (Match Term, Arg Term) -> m (Match Term, Arg Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Simplification -> IntMap (Arg Term) -> Match Term
    forall a. Simplification -> IntMap (Arg a) -> Match a
    Yes Simplification
    YesSimplification IntMap (Arg Term)
    forall a. Null a => a
    empty , Arg Term
    arg')
              | Bool
    otherwise          -> (Match Term, Arg Term) -> m (Match Term, Arg Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match Term
    forall a. Match a
    No                          , Arg Term
    arg')
          Blocked Blocker
    b Term
    _              -> (Match Term, Arg Term) -> m (Match Term, Arg Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Blocked () -> Match Term
    forall a. Blocked () -> Match a
    DontKnow (Blocked () -> Match Term) -> Blocked () -> Match Term
    forall a b. (a -> b) -> a -> b
    $ Blocker -> () -> Blocked ()
    forall t a. Blocker -> a -> Blocked' t a
    Blocked Blocker
    b ()     , Arg Term
    arg')
          NotBlocked NotBlocked' Term
    r Term
    t           -> (Match Term, Arg Term) -> m (Match Term, Arg Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Blocked () -> Match Term
    forall a. Blocked () -> Match a
    DontKnow (Blocked () -> Match Term) -> Blocked () -> Match Term
    forall a b. (a -> b) -> a -> b
    $ NotBlocked' Term -> () -> Blocked ()
    forall t a. NotBlocked' t -> a -> Blocked' t a
    NotBlocked NotBlocked' Term
    r' () , Arg Term
    arg')
            where r' :: NotBlocked' Term
    r' = Elim -> NotBlocked' Term -> NotBlocked' Term
    forall t. Elim' t -> NotBlocked' t -> NotBlocked' t
    stuckOn (Arg Term -> Elim
    forall a. Arg a -> Elim' a
    Apply Arg Term
    arg') NotBlocked' Term
    r

      -- Case constructor pattern.
      (ConP ConHead
    c ConPatternInfo
    cpi [NamedArg DeBruijnPattern]
    ps, Arg ArgInfo
    info Term
    v) -> do
        if Bool -> Bool
    not (ConPatternInfo -> Bool
    conPRecord ConPatternInfo
    cpi) then ConHead
    -> [NamedArg DeBruijnPattern]
    -> Arg Term
    -> m (Match Term, Arg Term)
    forall (m :: * -> *).
    MonadMatch m =>
    ConHead
    -> [NamedArg DeBruijnPattern]
    -> Arg Term
    -> m (Match Term, Arg Term)
    fallback ConHead
    c [NamedArg DeBruijnPattern]
    ps (ArgInfo -> Term -> Arg Term
    forall e. ArgInfo -> e -> Arg e
    Arg ArgInfo
    info Term
    v) else do
        QName -> m (Maybe [Arg QName])
    forall (m :: * -> *).
    HasConstInfo m =>
    QName -> m (Maybe [Arg QName])
    isEtaRecordCon (ConHead -> QName
    conName ConHead
    c) m (Maybe [Arg QName])
    -> (Maybe [Arg QName] -> m (Match Term, Arg Term))
    -> m (Match Term, Arg Term)
    forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
    >>= \case
          Maybe [Arg QName]
    Nothing -> ConHead
    -> [NamedArg DeBruijnPattern]
    -> Arg Term
    -> m (Match Term, Arg Term)
    forall (m :: * -> *).
    MonadMatch m =>
    ConHead
    -> [NamedArg DeBruijnPattern]
    -> Arg Term
    -> m (Match Term, Arg Term)
    fallback ConHead
    c [NamedArg DeBruijnPattern]
    ps (ArgInfo -> Term -> Arg Term
    forall e. ArgInfo -> e -> Arg e
    Arg ArgInfo
    info Term
    v)
          Just [Arg QName]
    fs -> do
            -- Case: Eta record constructor.
            -- This case is necessary if we want to use the clauses before
            -- record pattern translation (e.g., in type-checking definitions by copatterns).
            Bool -> m () -> m ()
    forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
    unless ([Arg QName] -> Int
    forall a. Sized a => a -> Int
    size [Arg QName]
    fs Int -> Int -> Bool
    forall a. Eq a => a -> a -> Bool
    == [NamedArg DeBruijnPattern] -> Int
    forall a. Sized a => a -> Int
    size [NamedArg DeBruijnPattern]
    ps) m ()
    forall a. HasCallStack => a
    __IMPOSSIBLE__
            ([Arg Term] -> Arg Term)
    -> (Match Term, [Arg Term]) -> (Match Term, Arg Term)
    forall b d a. (b -> d) -> (a, b) -> (a, d)
    mapSnd (ArgInfo -> Term -> Arg Term
    forall e. ArgInfo -> e -> Arg e
    Arg ArgInfo
    info (Term -> Arg Term)
    -> ([Arg Term] -> Term) -> [Arg Term] -> Arg Term
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . ConHead -> ConInfo -> [Elim] -> Term
    Con ConHead
    c (ConPatternInfo -> ConInfo
    fromConPatternInfo ConPatternInfo
    cpi) ([Elim] -> Term) -> ([Arg Term] -> [Elim]) -> [Arg Term] -> Term
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . (Arg Term -> Elim) -> [Arg Term] -> [Elim]
    forall a b. (a -> b) -> [a] -> [b]
    map Arg Term -> Elim
    forall a. Arg a -> Elim' a
    Apply) ((Match Term, [Arg Term]) -> (Match Term, Arg Term))
    -> m (Match Term, [Arg Term]) -> m (Match Term, Arg Term)
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    <$> do
              [NamedArg DeBruijnPattern]
    -> [Arg Term] -> m (Match Term, [Arg Term])
    forall (m :: * -> *).
    MonadMatch m =>
    [NamedArg DeBruijnPattern]
    -> [Arg Term] -> m (Match Term, [Arg Term])
    matchPatterns [NamedArg DeBruijnPattern]
    ps ([Arg Term] -> m (Match Term, [Arg Term]))
    -> [Arg Term] -> m (Match Term, [Arg Term])
    forall a b. (a -> b) -> a -> b
    $ [Arg QName] -> (Arg QName -> Arg Term) -> [Arg Term]
    forall (m :: * -> *) a b. Functor m => m a -> (a -> b) -> m b
    for [Arg QName]
    fs ((Arg QName -> Arg Term) -> [Arg Term])
    -> (Arg QName -> Arg Term) -> [Arg Term]
    forall a b. (a -> b) -> a -> b
    $ \ (Arg ArgInfo
    ai QName
    f) -> ArgInfo -> Term -> Arg Term
    forall e. ArgInfo -> e -> Arg e
    Arg ArgInfo
    ai (Term -> Arg Term) -> Term -> Arg Term
    forall a b. (a -> b) -> a -> b
    $ Term
    v Term -> [Elim] -> Term
    forall t. Apply t => t -> [Elim] -> t
    `applyE` [ProjOrigin -> QName -> Elim
    forall a. ProjOrigin -> QName -> Elim' a
    Proj ProjOrigin
    ProjSystem QName
    f]
        where
        isEtaRecordCon :: HasConstInfo m => QName -> m (Maybe [Arg QName])
        isEtaRecordCon :: forall (m :: * -> *).
    HasConstInfo m =>
    QName -> m (Maybe [Arg QName])
    isEtaRecordCon QName
    c = do
          (Definition -> Defn
    theDef (Definition -> Defn) -> m Definition -> m Defn
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    <$> QName -> m Definition
    forall (m :: * -> *). HasConstInfo m => QName -> m Definition
    getConstInfo QName
    c) m Defn -> (Defn -> m (Maybe [Arg QName])) -> m (Maybe [Arg QName])
    forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
    >>= \case
            Constructor{ conData :: Defn -> QName
    conData = QName
    d } -> do
              (Definition -> Defn
    theDef (Definition -> Defn) -> m Definition -> m Defn
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    <$> QName -> m Definition
    forall (m :: * -> *). HasConstInfo m => QName -> m Definition
    getConstInfo QName
    d) m Defn -> (Defn -> m (Maybe [Arg QName])) -> m (Maybe [Arg QName])
    forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
    >>= \case
                r :: Defn
    r@Record{ recFields :: Defn -> [Dom QName]
    recFields = [Dom QName]
    fs } | HasEta' PatternOrCopattern
    YesEta <- Defn -> HasEta' PatternOrCopattern
    recEtaEquality Defn
    r -> Maybe [Arg QName] -> m (Maybe [Arg QName])
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Maybe [Arg QName] -> m (Maybe [Arg QName]))
    -> Maybe [Arg QName] -> m (Maybe [Arg QName])
    forall a b. (a -> b) -> a -> b
    $ [Arg QName] -> Maybe [Arg QName]
    forall a. a -> Maybe a
    Just ([Arg QName] -> Maybe [Arg QName])
    -> [Arg QName] -> Maybe [Arg QName]
    forall a b. (a -> b) -> a -> b
    $ (Dom QName -> Arg QName) -> [Dom QName] -> [Arg QName]
    forall a b. (a -> b) -> [a] -> [b]
    map Dom QName -> Arg QName
    forall t a. Dom' t a -> Arg a
    argFromDom [Dom QName]
    fs
                Defn
    _ -> Maybe [Arg QName] -> m (Maybe [Arg QName])
    forall (m :: * -> *) a. Monad m => a -> m a
    return Maybe [Arg QName]
    forall a. Maybe a
    Nothing
            Defn
    _ -> m (Maybe [Arg QName])
    forall a. HasCallStack => a
    __IMPOSSIBLE__
      (DefP PatternInfo
    o QName
    q [NamedArg DeBruijnPattern]
    ps, Arg Term
    v) -> do
        let f :: Term -> Maybe ([Elim] -> Term, [Elim])
    f (Def QName
    q' [Elim]
    vs) | QName
    q QName -> QName -> Bool
    forall a. Eq a => a -> a -> Bool
    == QName
    q' = ([Elim] -> Term, [Elim]) -> Maybe ([Elim] -> Term, [Elim])
    forall a. a -> Maybe a
    Just (QName -> [Elim] -> Term
    Def QName
    q, [Elim]
    vs)
            f Term
    _                     = Maybe ([Elim] -> Term, [Elim])
    forall a. Maybe a
    Nothing
        (Term -> Maybe ([Elim] -> Term, [Elim]))
    -> [NamedArg DeBruijnPattern]
    -> Arg Term
    -> m (Match Term, Arg Term)
    forall (m :: * -> *).
    MonadMatch m =>
    (Term -> Maybe ([Elim] -> Term, [Elim]))
    -> [NamedArg DeBruijnPattern]
    -> Arg Term
    -> m (Match Term, Arg Term)
    fallback' Term -> Maybe ([Elim] -> Term, [Elim])
    f [NamedArg DeBruijnPattern]
    ps Arg Term
    v
     where
        -- Default: not an eta record constructor.
      fallback :: MonadMatch m
               => ConHead -> [NamedArg DeBruijnPattern] -> Arg Term -> m (Match Term, Arg Term)
      fallback :: forall (m :: * -> *).
    MonadMatch m =>
    ConHead
    -> [NamedArg DeBruijnPattern]
    -> Arg Term
    -> m (Match Term, Arg Term)
    fallback ConHead
    c [NamedArg DeBruijnPattern]
    ps Arg Term
    v = do
        let f :: Term -> Maybe ([Elim] -> Term, [Elim])
    f (Con ConHead
    c' ConInfo
    ci' [Elim]
    vs) | ConHead
    c ConHead -> ConHead -> Bool
    forall a. Eq a => a -> a -> Bool
    == ConHead
    c' = ([Elim] -> Term, [Elim]) -> Maybe ([Elim] -> Term, [Elim])
    forall a. a -> Maybe a
    Just (ConHead -> ConInfo -> [Elim] -> Term
    Con ConHead
    c' ConInfo
    ci',[Elim]
    vs)
            f Term
    _                         = Maybe ([Elim] -> Term, [Elim])
    forall a. Maybe a
    Nothing
        (Term -> Maybe ([Elim] -> Term, [Elim]))
    -> [NamedArg DeBruijnPattern]
    -> Arg Term
    -> m (Match Term, Arg Term)
    forall (m :: * -> *).
    MonadMatch m =>
    (Term -> Maybe ([Elim] -> Term, [Elim]))
    -> [NamedArg DeBruijnPattern]
    -> Arg Term
    -> m (Match Term, Arg Term)
    fallback' Term -> Maybe ([Elim] -> Term, [Elim])
    f [NamedArg DeBruijnPattern]
    ps Arg Term
    v

      -- Regardless of blocking, constructors and a properly applied @hcomp@
      -- can be matched on.
      isMatchable' :: HasBuiltins m => m (Blocked Term -> Maybe Term)
      isMatchable' :: forall (m :: * -> *).
    HasBuiltins m =>
    m (Blocked Term -> Maybe Term)
    isMatchable' = do
        Maybe QName
    mhcomp <- VerboseKey -> m (Maybe QName)
    forall (m :: * -> *).
    HasBuiltins m =>
    VerboseKey -> m (Maybe QName)
    getName' VerboseKey
    builtinHComp
        (Blocked Term -> Maybe Term) -> m (Blocked Term -> Maybe Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return ((Blocked Term -> Maybe Term) -> m (Blocked Term -> Maybe Term))
    -> (Blocked Term -> Maybe Term) -> m (Blocked Term -> Maybe Term)
    forall a b. (a -> b) -> a -> b
    $ \ Blocked Term
    r ->
          case Blocked Term -> Term
    forall t a. Blocked' t a -> a
    ignoreBlocking Blocked Term
    r of
            t :: Term
    t@Con{} -> Term -> Maybe Term
    forall a. a -> Maybe a
    Just Term
    t
            t :: Term
    t@(Def QName
    q [Elim
    l,Elim
    a,Elim
    phi,Elim
    u,Elim
    u0]) | QName -> Maybe QName
    forall a. a -> Maybe a
    Just QName
    q Maybe QName -> Maybe QName -> Bool
    forall a. Eq a => a -> a -> Bool
    == Maybe QName
    mhcomp
                    -> Term -> Maybe Term
    forall a. a -> Maybe a
    Just Term
    t
            Term
    _       -> Maybe Term
    forall a. Maybe a
    Nothing

      -- DefP hcomp and ConP matching.
      fallback' :: MonadMatch m
                => (Term -> Maybe (Elims -> Term , Elims))
                -> [NamedArg DeBruijnPattern]
                -> Arg Term
                -> m (Match Term, Arg Term)
      fallback' :: forall (m :: * -> *).
    MonadMatch m =>
    (Term -> Maybe ([Elim] -> Term, [Elim]))
    -> [NamedArg DeBruijnPattern]
    -> Arg Term
    -> m (Match Term, Arg Term)
    fallback' Term -> Maybe ([Elim] -> Term, [Elim])
    mtc [NamedArg DeBruijnPattern]
    ps (Arg ArgInfo
    info Term
    v) = do
            Blocked Term -> Maybe Term
    isMatchable <- m (Blocked Term -> Maybe Term)
    forall (m :: * -> *).
    HasBuiltins m =>
    m (Blocked Term -> Maybe Term)
    isMatchable'

            Blocked Term
    w <- Term -> m (Blocked Term)
    forall a (m :: * -> *).
    (Reduce a, MonadReduce m) =>
    a -> m (Blocked a)
    reduceB Term
    v
            -- Unfold delayed (corecursive) definitions one step. This is
            -- only necessary if c is a coinductive constructor, but
            -- 1) it does not hurt to do it all the time, and
            -- 2) whatInduction c sometimes crashes because c may point to
            --    an axiom at this stage (if we are checking the
            --    projection functions for a record type).
    {-
            w <- case w of
                   NotBlocked r (Def f es) ->   -- Andreas, 2014-06-12 TODO: r == ReallyNotBlocked sufficient?
                     unfoldDefinitionE True reduceB' (Def f []) f es
                       -- reduceB is used here because some constructors
                       -- are actually definitions which need to be
                       -- unfolded (due to open public).
                   _ -> return w
    -}
            -- Jesper, 23-06-2016: Note that unfoldCorecursion may destroy
            -- constructor forms, so we only call constructorForm after.
            Blocked Term
    w <- (Term -> m Term) -> Blocked Term -> m (Blocked Term)
    forall (t :: * -> *) (f :: * -> *) a b.
    (Traversable t, Applicative f) =>
    (a -> f b) -> t a -> f (t b)
    traverse Term -> m Term
    forall (m :: * -> *). HasBuiltins m => Term -> m Term
    constructorForm (Blocked Term -> m (Blocked Term))
    -> m (Blocked Term) -> m (Blocked Term)
    forall (m :: * -> *) a b. Monad m => (a -> m b) -> m a -> m b
    =<< case Blocked Term
    w of
                   NotBlocked NotBlocked' Term
    r Term
    u -> ReduceM (Blocked Term) -> m (Blocked Term)
    forall (m :: * -> *) a. MonadReduce m => ReduceM a -> m a
    liftReduce (ReduceM (Blocked Term) -> m (Blocked Term))
    -> ReduceM (Blocked Term) -> m (Blocked Term)
    forall a b. (a -> b) -> a -> b
    $ Term -> ReduceM (Blocked Term)
    unfoldCorecursion Term
    u  -- Andreas, 2014-06-12 TODO: r == ReallyNotBlocked sufficient?
                   Blocked Term
    _ -> Blocked Term -> m (Blocked Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return Blocked Term
    w
            let v :: Term
    v = Blocked Term -> Term
    forall t a. Blocked' t a -> a
    ignoreBlocking Blocked Term
    w
                arg :: Arg Term
    arg = ArgInfo -> Term -> Arg Term
    forall e. ArgInfo -> e -> Arg e
    Arg ArgInfo
    info Term
    v  -- the reduced argument

            case Blocked Term
    w of
              Blocked Term
    b | Just Term
    t <- Blocked Term -> Maybe Term
    isMatchable Blocked Term
    b ->
                case Term -> Maybe ([Elim] -> Term, [Elim])
    mtc Term
    t of
                  Just ([Elim] -> Term
    bld, [Elim]
    vs) -> do
                    (Match Term
    m, [Arg Term]
    vs1) <- (Match Term, [Arg Term]) -> (Match Term, [Arg Term])
    forall a b. (Match a, b) -> (Match a, b)
    yesSimplification ((Match Term, [Arg Term]) -> (Match Term, [Arg Term]))
    -> m (Match Term, [Arg Term]) -> m (Match Term, [Arg Term])
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    <$> [NamedArg DeBruijnPattern]
    -> [Arg Term] -> m (Match Term, [Arg Term])
    forall (m :: * -> *).
    MonadMatch m =>
    [NamedArg DeBruijnPattern]
    -> [Arg Term] -> m (Match Term, [Arg Term])
    matchPatterns [NamedArg DeBruijnPattern]
    ps ([Arg Term] -> Maybe [Arg Term] -> [Arg Term]
    forall a. a -> Maybe a -> a
    fromMaybe [Arg Term]
    forall a. HasCallStack => a
    __IMPOSSIBLE__ (Maybe [Arg Term] -> [Arg Term]) -> Maybe [Arg Term] -> [Arg Term]
    forall a b. (a -> b) -> a -> b
    $ [Elim] -> Maybe [Arg Term]
    forall a. [Elim' a] -> Maybe [Arg a]
    allApplyElims [Elim]
    vs)
                    (Match Term, Arg Term) -> m (Match Term, Arg Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match Term
    m, ArgInfo -> Term -> Arg Term
    forall e. ArgInfo -> e -> Arg e
    Arg ArgInfo
    info (Term -> Arg Term) -> Term -> Arg Term
    forall a b. (a -> b) -> a -> b
    $ [Elim] -> Term
    bld ([Elim] -> [Arg Term] -> [Elim]
    mergeElims [Elim]
    vs [Arg Term]
    vs1))
                  Maybe ([Elim] -> Term, [Elim])
    Nothing
                                        -> (Match Term, Arg Term) -> m (Match Term, Arg Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match Term
    forall a. Match a
    No                          , Arg Term
    arg)
              Blocked Blocker
    b Term
    _               -> (Match Term, Arg Term) -> m (Match Term, Arg Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Blocked () -> Match Term
    forall a. Blocked () -> Match a
    DontKnow (Blocked () -> Match Term) -> Blocked () -> Match Term
    forall a b. (a -> b) -> a -> b
    $ Blocker -> () -> Blocked ()
    forall t a. Blocker -> a -> Blocked' t a
    Blocked Blocker
    b ()     , Arg Term
    arg)
              NotBlocked NotBlocked' Term
    r Term
    _            -> (Match Term, Arg Term) -> m (Match Term, Arg Term)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Blocked () -> Match Term
    forall a. Blocked () -> Match a
    DontKnow (Blocked () -> Match Term) -> Blocked () -> Match Term
    forall a b. (a -> b) -> a -> b
    $ NotBlocked' Term -> () -> Blocked ()
    forall t a. NotBlocked' t -> a -> Blocked' t a
    NotBlocked NotBlocked' Term
    r' () , Arg Term
    arg)
                where r' :: NotBlocked' Term
    r' = Elim -> NotBlocked' Term -> NotBlocked' Term
    forall t. Elim' t -> NotBlocked' t -> NotBlocked' t
    stuckOn (Arg Term -> Elim
    forall a. Arg a -> Elim' a
    Apply Arg Term
    arg) NotBlocked' Term
    r

    -- ASR (08 November 2014). The type of the function could be
    --
    -- @(Match Term, [Arg Term]) -> (Match Term, [Arg Term])@.
    yesSimplification :: (Match a, b) -> (Match a, b)
    yesSimplification :: forall a b. (Match a, b) -> (Match a, b)
    yesSimplification (Yes Simplification
    _ IntMap (Arg a)
    vs, b
    us) = (Simplification -> IntMap (Arg a) -> Match a
    forall a. Simplification -> IntMap (Arg a) -> Match a
    Yes Simplification
    YesSimplification IntMap (Arg a)
    vs, b
    us)
    yesSimplification (Match a, b)
    r              = (Match a, b)
    r

    -- Matching patterns against patterns -------------------------------------

    -- | Match a single pattern.
    matchPatternP :: MonadMatch m
                  => DeBruijnPattern
                  -> Arg DeBruijnPattern
                  -> m (Match DeBruijnPattern)
    matchPatternP :: forall (m :: * -> *).
    MonadMatch m =>
    DeBruijnPattern -> Arg DeBruijnPattern -> m (Match DeBruijnPattern)
    matchPatternP DeBruijnPattern
    p (Arg ArgInfo
    info (DotP PatternInfo
    _ Term
    v)) = do
      (Match Term
    m, Arg Term
    arg) <- DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term)
    forall (m :: * -> *).
    MonadMatch m =>
    DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term)
    matchPattern DeBruijnPattern
    p (ArgInfo -> Term -> Arg Term
    forall e. ArgInfo -> e -> Arg e
    Arg ArgInfo
    info Term
    v)
      Match DeBruijnPattern -> m (Match DeBruijnPattern)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match DeBruijnPattern -> m (Match DeBruijnPattern))
    -> Match DeBruijnPattern -> m (Match DeBruijnPattern)
    forall a b. (a -> b) -> a -> b
    $ (Term -> DeBruijnPattern) -> Match Term -> Match DeBruijnPattern
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap (PatternInfo -> Term -> DeBruijnPattern
    forall x. PatternInfo -> Term -> Pattern' x
    DotP PatternInfo
    defaultPatternInfo) Match Term
    m
    matchPatternP DeBruijnPattern
    p arg :: Arg DeBruijnPattern
    arg@(Arg ArgInfo
    info DeBruijnPattern
    q) = do
      let varMatch :: DBPatVar -> m (Match DeBruijnPattern)
    varMatch DBPatVar
    x = Match DeBruijnPattern -> m (Match DeBruijnPattern)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match DeBruijnPattern -> m (Match DeBruijnPattern))
    -> Match DeBruijnPattern -> m (Match DeBruijnPattern)
    forall a b. (a -> b) -> a -> b
    $ Simplification
    -> IntMap (Arg DeBruijnPattern) -> Match DeBruijnPattern
    forall a. Simplification -> IntMap (Arg a) -> Match a
    Yes Simplification
    NoSimplification (IntMap (Arg DeBruijnPattern) -> Match DeBruijnPattern)
    -> IntMap (Arg DeBruijnPattern) -> Match DeBruijnPattern
    forall a b. (a -> b) -> a -> b
    $ (Int, Arg DeBruijnPattern) -> IntMap (Arg DeBruijnPattern)
    forall el coll. Singleton el coll => el -> coll
    singleton (DBPatVar -> Int
    dbPatVarIndex DBPatVar
    x, Arg DeBruijnPattern
    arg)
          termMatch :: m (Match DeBruijnPattern)
    termMatch  = do
            (Match Term
    m, Arg Term
    arg) <- DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term)
    forall (m :: * -> *).
    MonadMatch m =>
    DeBruijnPattern -> Arg Term -> m (Match Term, Arg Term)
    matchPattern DeBruijnPattern
    p ((DeBruijnPattern -> Term) -> Arg DeBruijnPattern -> Arg Term
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap DeBruijnPattern -> Term
    patternToTerm Arg DeBruijnPattern
    arg)
            Match DeBruijnPattern -> m (Match DeBruijnPattern)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match DeBruijnPattern -> m (Match DeBruijnPattern))
    -> Match DeBruijnPattern -> m (Match DeBruijnPattern)
    forall a b. (a -> b) -> a -> b
    $ (Term -> DeBruijnPattern) -> Match Term -> Match DeBruijnPattern
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap (PatternInfo -> Term -> DeBruijnPattern
    forall x. PatternInfo -> Term -> Pattern' x
    DotP PatternInfo
    defaultPatternInfo) Match Term
    m
      case DeBruijnPattern
    p of
        ProjP{}         -> m (Match DeBruijnPattern)
    forall a. HasCallStack => a
    __IMPOSSIBLE__
        IApplyP PatternInfo
    _ Term
    _ Term
    _ DBPatVar
    x -> DBPatVar -> m (Match DeBruijnPattern)
    varMatch DBPatVar
    x
        VarP PatternInfo
    _ DBPatVar
    x        -> DBPatVar -> m (Match DeBruijnPattern)
    varMatch DBPatVar
    x
        DotP PatternInfo
    _ Term
    _        -> Match DeBruijnPattern -> m (Match DeBruijnPattern)
    forall (m :: * -> *) a. Monad m => a -> m a
    return (Match DeBruijnPattern -> m (Match DeBruijnPattern))
    -> Match DeBruijnPattern -> m (Match DeBruijnPattern)
    forall a b. (a -> b) -> a -> b
    $ Simplification
    -> IntMap (Arg DeBruijnPattern) -> Match DeBruijnPattern
    forall a. Simplification -> IntMap (Arg a) -> Match a
    Yes Simplification
    NoSimplification IntMap (Arg DeBruijnPattern)
    forall a. Null a => a
    empty
        LitP{}          -> m (Match DeBruijnPattern)
    termMatch -- Literal patterns bind no variables so we can fall back to the Term version.
        DefP{}          -> m (Match DeBruijnPattern)
    termMatch

        ConP ConHead
    c ConPatternInfo
    cpi [NamedArg DeBruijnPattern]
    ps ->
          case DeBruijnPattern
    q of
            ConP ConHead
    c' ConPatternInfo
    _ [NamedArg DeBruijnPattern]
    qs | ConHead
    c ConHead -> ConHead -> Bool
    forall a. Eq a => a -> a -> Bool
    == ConHead
    c'   -> [NamedArg DeBruijnPattern]
    -> [Arg DeBruijnPattern] -> m (Match DeBruijnPattern)
    forall (m :: * -> *).
    MonadMatch m =>
    [NamedArg DeBruijnPattern]
    -> [Arg DeBruijnPattern] -> m (Match DeBruijnPattern)
    matchPatternsP [NamedArg DeBruijnPattern]
    ps (((NamedArg DeBruijnPattern -> Arg DeBruijnPattern)
    -> [NamedArg DeBruijnPattern] -> [Arg DeBruijnPattern]
    forall a b. (a -> b) -> [a] -> [b]
    map ((NamedArg DeBruijnPattern -> Arg DeBruijnPattern)
     -> [NamedArg DeBruijnPattern] -> [Arg DeBruijnPattern])
    -> ((Named NamedName DeBruijnPattern -> DeBruijnPattern)
        -> NamedArg DeBruijnPattern -> Arg DeBruijnPattern)
    -> (Named NamedName DeBruijnPattern -> DeBruijnPattern)
    -> [NamedArg DeBruijnPattern]
    -> [Arg DeBruijnPattern]
    forall b c a. (b -> c) -> (a -> b) -> a -> c
    . (Named NamedName DeBruijnPattern -> DeBruijnPattern)
    -> NamedArg DeBruijnPattern -> Arg DeBruijnPattern
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap) Named NamedName DeBruijnPattern -> DeBruijnPattern
    forall name a. Named name a -> a
    namedThing [NamedArg DeBruijnPattern]
    qs)
                         | Bool
    otherwise -> Match DeBruijnPattern -> m (Match DeBruijnPattern)
    forall (m :: * -> *) a. Monad m => a -> m a
    return Match DeBruijnPattern
    forall a. Match a
    No
            LitP{} -> (DeBruijnPattern -> DeBruijnPattern)
    -> Match DeBruijnPattern -> Match DeBruijnPattern
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    fmap DeBruijnPattern -> DeBruijnPattern
    forall {x} {a}. Pattern' x -> Pattern' a
    toLitP (Match DeBruijnPattern -> Match DeBruijnPattern)
    -> m (Match DeBruijnPattern) -> m (Match DeBruijnPattern)
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    <$> m (Match DeBruijnPattern)
    termMatch
              where toLitP :: Pattern' x -> Pattern' a
    toLitP (DotP PatternInfo
    _ (Lit Literal
    l)) = Literal -> Pattern' a
    forall a. Literal -> Pattern' a
    litP Literal
    l   -- All bindings should be to literals
                    toLitP Pattern' x
    _                = Pattern' a
    forall a. HasCallStack => a
    __IMPOSSIBLE__
            DeBruijnPattern
    _      -> m (Match DeBruijnPattern)
    termMatch

    matchPatternsP :: MonadMatch m
                   => [NamedArg DeBruijnPattern]
                   -> [Arg DeBruijnPattern]
                   -> m (Match DeBruijnPattern)
    matchPatternsP :: forall (m :: * -> *).
    MonadMatch m =>
    [NamedArg DeBruijnPattern]
    -> [Arg DeBruijnPattern] -> m (Match DeBruijnPattern)
    matchPatternsP [NamedArg DeBruijnPattern]
    ps [Arg DeBruijnPattern]
    qs = do
      [Match DeBruijnPattern] -> Match DeBruijnPattern
    forall a. Monoid a => [a] -> a
    mconcat ([Match DeBruijnPattern] -> Match DeBruijnPattern)
    -> m [Match DeBruijnPattern] -> m (Match DeBruijnPattern)
    forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
    <$> (DeBruijnPattern
     -> Arg DeBruijnPattern -> m (Match DeBruijnPattern))
    -> [DeBruijnPattern]
    -> [Arg DeBruijnPattern]
    -> m [Match DeBruijnPattern]
    forall (m :: * -> *) a b c.
    Applicative m =>
    (a -> b -> m c) -> [a] -> [b] -> m [c]
    zipWithM DeBruijnPattern -> Arg DeBruijnPattern -> m (Match DeBruijnPattern)
    forall (m :: * -> *).
    MonadMatch m =>
    DeBruijnPattern -> Arg DeBruijnPattern -> m (Match DeBruijnPattern)
    matchPatternP ((NamedArg DeBruijnPattern -> DeBruijnPattern)
    -> [NamedArg DeBruijnPattern] -> [DeBruijnPattern]
    forall a b. (a -> b) -> [a] -> [b]
    map NamedArg DeBruijnPattern -> DeBruijnPattern
    forall a. NamedArg a -> a
    namedArg [NamedArg DeBruijnPattern]
    ps) [Arg DeBruijnPattern]
    qs