Safe Haskell	None
Language	Haskell2010

Data.HList.HList

Contents

Heterogeneous type sequences
Basic list functions
- Append
- Alternative append
- Historical append
Reversing HLists
A nicer notation for lists
- examples
  - historical
folds
- foldr
- foldl
unfolds
- unfold
- replicate
- iterate
concat
traversing HLists
- producing HList
- producing homogenous lists
  - map (no sequencing)
  - mapM
Ensure a list to contain HNats only
Membership tests
- Another type-level membership test
Staged equality for lists
Find an element in a set based on HEq
- Membership test based on type equality
Intersection based on HTMember
Convert between heterogeneous lists and homogeneous ones
With HMaybe
- Turn list in a list of justs
- Extract justs from list of maybes
  - alternative implementation
Annotated lists
Splitting by HTrue and HFalse
Splitting by Length
- take
- drop
Conversion to and from tuples
partition
groupBy
span
zip
Monoid instance
- helper functions

Description

The HList library

Basic declarations for typeful heterogeneous lists.

Synopsis

data family HList (l :: [*])
class HProxiesFD (xs :: [*]) pxs | pxs -> xs, xs -> pxs where
- hProxies :: HList pxs
type HProxies xs = HProxiesFD xs (AddProxy xs)
type family AddProxy (xs :: k) :: k
type family DropProxy (xs :: k) :: k
data ReadElement = ReadElement
hHead :: HList (e ': l) -> e
hTail :: HList (e ': l) -> HList l
hLast :: forall (l1 :: [Type]) e (l :: [Type]). HRevApp l1 ('[] :: [Type]) (e ': l) => HList l1 -> e
class HInit xs where
- type HInitR xs :: [*]
- hInit :: HList xs -> HList (HInitR xs)
type family HLength (x :: [k]) :: HNat
hLength :: HLengthEq l n => HList l -> Proxy n
type family HAppendListR (l1 :: [k]) (l2 :: [k]) :: [k]
class HAppendList l1 l2 where
- hAppendList :: HList l1 -> HList l2 -> HList (HAppendListR l1 l2)
append' :: [a] -> [a] -> [a]
hAppend' :: HFoldr FHCons v l r => HList l -> v -> r
data FHCons = FHCons
type family HRevAppR (l1 :: [k]) (l2 :: [k]) :: [k]
class HRevApp l1 l2 l3 | l1 l2 -> l3 where
- hRevApp :: HList l1 -> HList l2 -> HList l3
class HReverse xs sx | xs -> sx, sx -> xs where
- hReverse :: HList xs -> HList sx
hReverse_ :: forall (l1 :: [Type]) (l3 :: [Type]). HRevApp l1 ('[] :: [Type]) l3 => HList l1 -> HList l3
hEnd :: HList l -> HList l
hBuild :: HBuild' '[] r => r
class HBuild' l r where
- hBuild' :: HList l -> r
class HFoldr f v (l :: [*]) r where
- hFoldr :: f -> v -> HList l -> r
class HScanr f z ls rs where
- hScanr :: f -> z -> HList ls -> HList rs
class HFoldr1 f (l :: [*]) r where
- hFoldr1 :: f -> HList l -> r
class HFoldl f (z :: *) xs (r :: *) where
- hFoldl :: f -> z -> HList xs -> r
hUnfold :: forall f a (z :: [Type]). (HUnfoldFD f (ApplyR f a) z, Apply f a) => f -> a -> HList z
type HUnfold p s = HUnfoldR p (ApplyR p s)
type family HUnfoldR p res :: [*]
type HUnfold' p res = HUnfoldFD p (ApplyR p res) (HUnfold p res)
class HUnfoldFD p res z | p res -> z where
- hUnfold' :: p -> res -> HList z
class HLengthEq es n => HReplicateFD (n :: HNat) e es | n e -> es, es -> n where
- hReplicate :: Proxy n -> e -> HList es
type HReplicate n e = HReplicateFD n e (HReplicateR n e)
type family HReplicateR (n :: HNat) (e :: k) :: [k]
class HLengthEq r n => HReplicateF (n :: HNat) f z r | r -> n where
- hReplicateF :: HLengthEq r n => Proxy n -> f -> z -> HList r
class HLengthEq r n => HIterate n f z r where
- hIterate :: HLengthEq r n => Proxy n -> f -> z -> HList r
type HConcat xs = HConcatFD xs (HConcatR xs)
hConcat :: HConcat xs => HList xs -> HList (HConcatR xs)
type family HConcatR (a :: [*]) :: [*]
type family UnHList a :: [*]
class HConcatFD xxs xs | xxs -> xs where
- hConcatFD :: HList xxs -> HList xs
class HAppendFD a b ab | a b -> ab where
- hAppendFD :: HList a -> HList b -> HList ab
newtype HMap f = HMap f
hMap :: forall (a :: [Type]) (b :: [Type]) r f. (SameLength' a b, SameLength' b a, HMapAux r f a b) => f -> r a -> r b
hMapL :: forall (a :: [Type]) (b :: [Type]) f. (SameLength' a b, SameLength' b a, HMapAux HList f a b) => f -> HList a -> HList b
newtype HMapL f = HMapL f
class (SameLength a b, HMapAux r f a b) => HMapCxt r f a b
class HMapAux (r :: [*] -> *) f (x :: [*]) (y :: [*]) where
- hMapAux :: SameLength x y => f -> r x -> r y
newtype MapCar f = MapCar f
hMapMapCar :: HFoldr (MapCar f) (HList '[]) l l' => f -> HList l -> l'
hComposeList :: HFoldr Comp (a -> a) l (t -> a) => HList l -> t -> a
class (Applicative m, SameLength a b) => HSequence m a b | a -> b, m b -> a where
- hSequence :: HList a -> m (HList b)
hSequence2 :: forall f (l :: [Type]) a. (Applicative f, HFoldr (LiftA2 FHCons) (f (HList ('[] :: [Type]))) l (f a)) => HList l -> f a
newtype Mapcar f = Mapcar f
type HMapOut f l e = HFoldr (Mapcar f) [e] l [e]
hMapOut :: forall f e l. HMapOut f l e => f -> HList l -> [e]
hMapM :: (Monad m, HMapOut f l (m e)) => f -> HList l -> [m e]
hMapM_ :: (Monad m, HMapOut f l (m ())) => f -> HList l -> m ()
type family HNats (l :: [*]) :: [HNat]
hNats :: HList l -> Proxy (HNats l)
class HMember (e1 :: k) (l :: [k]) (b :: Bool) | e1 l -> b
class HMember' (b0 :: Bool) (e1 :: k) (l :: [k]) (b :: Bool) | b0 e1 l -> b
type family HMemberP pred e1 (l :: [*]) :: Bool
type family HMemberP' pred e1 (l :: [*]) pb :: Bool
hMember :: HMember e l b => Proxy e -> Proxy l -> Proxy b
class HMemberM (e1 :: k) (l :: [k]) (r :: Maybe [k]) | e1 l -> r
class HMemberM1 (b :: Bool) (e1 :: k) (l :: [k]) (r :: Maybe [k]) | b e1 l -> r
class HMemberM2 (b :: Maybe [k]) (e1 :: k) (l :: [k]) (r :: Maybe [k]) | b e1 l -> r
class HFind1 e l l n => HFind (e :: k) (l :: [k]) (n :: HNat) | e l -> n
class HFind1 (e :: k) (l :: [k]) (l0 :: [k]) (n :: HNat) | e l -> n
class HFind2 (b :: Bool) (e :: k) (l :: [k]) (l0 :: [k]) (n :: HNat) | b e l -> n
class HTMember e (l :: [*]) (b :: Bool) | e l -> b
hTMember :: HTMember e l b => e -> HList l -> Proxy b
class HTIntersect l1 l2 l3 | l1 l2 -> l3 where
- hTIntersect :: HList l1 -> HList l2 -> HList l3
class HTIntersectBool (b :: Bool) h t l1 l2 | b h t l1 -> l2 where
- hTIntersectBool :: Proxy b -> h -> HList t -> HList l1 -> HList l2
class HList2List l e | l -> e where
- hList2List :: HList l -> [e]
- list2HListSuffix :: [e] -> Maybe (HList l, [e])
list2HList :: HList2List l e => [e] -> Maybe (HList l)
listAsHList :: forall (l1 :: [Type]) e1 (l2 :: [Type]) e2 p f. (HList2List l1 e1, HList2List l2 e2, Choice p, Applicative f) => p (HList l2) (f (HList l1)) -> p [e2] (f [e1])
listAsHList' :: forall (l :: [Type]) e p f. (HList2List l e, Choice p, Applicative f) => p (HList l) (f (HList l)) -> p [e] (f [e])
class FromHJustR (ToHJustR l) ~ l => ToHJust l where
- type ToHJustR l :: [*]
- toHJust :: HList l -> HList (ToHJustR l)
toHJust2 :: (HMapCxt r (HJust ()) a b, ToHJust a, b ~ ToHJustR a) => r a -> r b
class FromHJustR (ToHJustR l) ~ l => FromHJust l where
- type FromHJustR l :: [*]
- fromHJust :: HList l -> HList (FromHJustR l)
fromHJust2 :: HMapCxt r HFromJust a b => r a -> r b
data HFromJust = HFromJust
data HAddTag t = HAddTag t
data HRmTag = HRmTag
hAddTag :: forall (a :: [Type]) (b :: [Type]) r t. (SameLength' a b, SameLength' b a, HMapAux r (HAddTag t) a b) => t -> r a -> r b
hRmTag :: forall (a :: [Type]) (b :: [Type]) r. (SameLength' a b, SameLength' b a, HMapAux r HRmTag a b) => r a -> r b
hFlag :: forall (a :: [Type]) (b :: [Type]) r. (SameLength' a b, SameLength' b a, HMapAux r (HAddTag (Proxy 'True)) a b) => r a -> r b
class HSplit l where
- type HSplitT l :: [*]
- type HSplitF l :: [*]
- hSplit :: HList l -> (HList (HSplitT l), HList (HSplitF l))
class (HLengthEq xs n, HAppendList1 xs ys xsys) => HSplitAt (n :: HNat) xsys xs ys | n xsys -> xs ys, xs ys -> xsys, xs -> n where
- hSplitAt :: Proxy n -> HList xsys -> (HList xs, HList ys)
class HSplitAt1 accum (n :: HNat) xsys xs ys | accum n xsys -> xs ys where
- hSplitAt1 :: HList accum -> Proxy n -> HList xsys -> (HList xs, HList ys)
class (SameLength' (HReplicateR n ()) xs, HLengthEq1 xs n, HLengthEq2 xs n) => HLengthEq (xs :: [*]) (n :: HNat) | xs -> n
class HLengthEq1 (xs :: [*]) n
class HLengthEq2 (xs :: [*]) n | xs -> n
class HLengthGe (xs :: [*]) (n :: HNat)
class HStripPrefix xs xsys ys => HAppendList1 (xs :: [k]) (ys :: [k]) (xsys :: [k]) | xs ys -> xsys, xs xsys -> ys
class HStripPrefix xs xsys ys | xs xsys -> ys
class HTake (n :: HNat) xs ys | n xs -> ys where
- hTake :: (HLengthEq ys n, HLengthGe xs n) => Proxy n -> HList xs -> HList ys
class HDrop (n :: HNat) xs ys | n xs -> ys where
- hDrop :: HLengthGe xs n => Proxy n -> HList xs -> HList ys
class HTuple v t | v -> t, t -> v where
- hToTuple :: HList v -> t
- hFromTuple :: t -> HList v
hTuple :: forall p f (v1 :: [Type]) a (v2 :: [Type]) t. (Profunctor p, Functor f, HTuple v1 a, HTuple v2 t) => p a (f t) -> p (HList v1) (f (HList v2))
hTuple' :: forall p f (v :: [Type]) a. (Profunctor p, Functor f, HTuple v a) => p a (f a) -> p (HList v) (f (HList v))
class HTails a b | a -> b, b -> a where
- hTails :: HList a -> HList b
class HInits a b | a -> b, b -> a where
- hInits :: HList a -> HList b
class HInits1 a b | a -> b, b -> a where
- hInits1 :: HList a -> HList b
data FHCons2 x = FHCons2 x
type family HMapCons (x :: *) (xxs :: [*]) :: [*]
type family HMapTail (xxs :: [*]) :: [*]
class HPartitionEq f x1 xs xi xo | f x1 xs -> xi xo where
- hPartitionEq :: Proxy f -> Proxy x1 -> HList xs -> (HList xi, HList xo)
class HPartitionEq1 (b :: Bool) f x1 x xs xi xo | b f x1 x xs -> xi xo where
- hPartitionEq1 :: Proxy b -> Proxy f -> Proxy x1 -> x -> HList xs -> (HList xi, HList xo)
class HGroupBy (f :: t) (as :: [*]) (gs :: [*]) | f as -> gs, gs -> as where
- hGroupBy :: Proxy f -> HList as -> HList gs
class HSpanEqBy (f :: t) (x :: *) (y :: [*]) (fst :: [*]) (snd :: [*]) | f x y -> fst snd, fst snd -> y where
- hSpanEqBy :: Proxy f -> x -> HList y -> (HList fst, HList snd)
class HSpanEqBy1 (f :: t) (x :: *) (y :: [*]) (i :: [*]) (o :: [*]) | f x y -> i o where
- hSpanEqBy1 :: Proxy f -> x -> HList y -> (HList i, HList o)
class HSpanEqBy2 (b :: Bool) (f :: t) (x :: *) (y :: *) (ys :: [*]) (i :: [*]) (o :: [*]) | b f x y ys -> i o where
- hSpanEqBy2 :: Proxy b -> Proxy f -> x -> y -> HList ys -> (HList i, HList o)
class HZipList x y l | x y -> l, l -> x y where
- hZipList :: HList x -> HList y -> HList l
- hUnzipList :: HList l -> (HList x, HList y)
data ConstMempty = ConstMempty
data UncurryMappend = UncurryMappend
data UncurrySappend = UncurrySappend

Heterogeneous type sequences

There are three sensible ways to define HLists:

data HList (l::[*]) where
    HNil  :: HList '[]
    HCons :: e -> HList l -> HList (e ': l)

This ensures that sequences can only be formed with Nil and Cons. The argument to HList is a promoted lists (kind [*]), which has a more attractive syntax.

Earlier versions of HList used an algebraic data type:

data HCons a b = HCons a b
data HNil = HNil

Disadvantages:

values with types like HCons Int Double to be created, which are nonsense to the functions in HList
some recursive functions do not need a class with the GADT. For example:

   hInit :: HListGADT (x ': xs) -> HListGADT (HInit (x ': xs))
   hInit (HCons x xs@(HCons _ _)) = HCons x (hInit xs)
   hInit (HCons _ HNil) = HNil

   type family HInit (xs :: [k]) :: [k]

but without the GADT, hInit is written as in a class, which complicates inferred types

Advantages

lazy pattern matches are allowed, so lazy pattern matching on a value undefined :: HList [a,b,c] can create the spine of the list. hProxies avoids the use of undefined, but a slightly more complicated class context has to be written or inferred.
type inference is better if you want to directly pattern match see stackoverflow post here
better pattern exhaustiveness checking (as of ghc-7.8)
standalone deriving works
Data.Coerce.coerce works because the parameters have role representational, not nominal as they are for the GADT and data family. Probably the GADT/type family actually do have a representational role: http://stackoverflow.com/questions/24222552/does-this-gadt-actually-have-type-role-representational

The data family version (currently used) gives the same type constructor HList :: [*] -> * as the GADT, while pattern matching behaves like the algebraic data type. Furthermore, nonsense values like HCons 1 2 :: HCons Int Int cannot be written with the data family.

A variation on the data family version is

data instance HList '[] = HNil
newtype instance HList (x ': xs) = HCons1 (x, HList xs)
pattern HCons x xs = HCons1 (x, xs)

This allows HList to have a nominal role, but on the other hand the PatternSynonym is not supported with ghc-7.6 and exhaustiveness checking is not as good (warnings for _ being unmatched)

data family HList (l :: [*]) infixr 2 Source #

Instances

Instances details

(SameLengths '[x, y, xy], HZipList x y xy) => HZip HList x y xy Source #
Instance details Defined in Data.HList.HList Methods hZip :: HList x -> HList y -> HList xy Source #
(SameLengths '[x, y, xy], HZipList x y xy) => HUnzip HList x y xy Source #
Instance details Defined in Data.HList.HList Methods hUnzip :: HList xy -> (HList x, HList y) Source #
HDeleteMany (e :: k) (HList ('[] :: [Type])) (HList ('[] :: [Type])) Source #
Instance details Defined in Data.HList.HTypeIndexed Methods hDeleteMany :: Proxy e -> HList '[] -> HList '[] Source #
HMapAux HList f ('[] :: [Type]) ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hMapAux :: f -> HList '[] -> HList '[] Source #
(HSpanEqBy f a as fst snd, HGroupBy f snd gs) => HGroupBy (f :: t) (a ': as) (HList (a ': fst) ': gs) Source #
Instance details Defined in Data.HList.HList Methods hGroupBy :: Proxy f -> HList (a ': as) -> HList (HList (a ': fst) ': gs) Source #
(ApplyAB f e e', HMapAux HList f l l', SameLength l l') => HMapAux HList f (e ': l) (e' ': l') Source #
Instance details Defined in Data.HList.HList Methods hMapAux :: f -> HList (e ': l) -> HList (e' ': l') Source #
(HOccurs e l, HProject l (HList l')) => HProject l (HList (e ': l')) Source #
Instance details Defined in Data.HList.HOccurs Methods hProject :: l -> HList (e ': l') Source #
(HOccurrence e (x ': y) l', HOccurs' e l' (x ': y)) => HOccurs e (HList (x ': y)) Source #
Instance details Defined in Data.HList.HOccurs Methods hOccurs :: HList (x ': y) -> e Source #
HExtend e (HList l) Source #
Instance details Defined in Data.HList.HList Associated Types type HExtendR e (HList l) Source # Methods (.*.) :: e -> HList l -> HExtendR e (HList l) Source #
HReverse l l' => HBuild' l (HList l') Source #
Instance details Defined in Data.HList.HList Methods hBuild' :: HList l -> HList l' Source #
HInits1 a b => HInits a (HList ('[] :: [Type]) ': b) Source #
Instance details Defined in Data.HList.HList Methods hInits :: HList a -> HList (HList '[] ': b) Source #
(Bounded x, Bounded (HList xs)) => Bounded (HList (x ': xs)) Source #
Instance details Defined in Data.HList.HList Methods minBound :: HList (x ': xs) # maxBound :: HList (x ': xs) #
Bounded (HList ('[] :: [Type])) Source #
Instance details Defined in Data.HList.HList Methods minBound :: HList '[] # maxBound :: HList '[] #
(Eq x, Eq (HList xs)) => Eq (HList (x ': xs)) Source #
Instance details Defined in Data.HList.HList Methods (==) :: HList (x ': xs) -> HList (x ': xs) -> Bool # (/=) :: HList (x ': xs) -> HList (x ': xs) -> Bool #
Eq (HList ('[] :: [Type])) Source #
Instance details Defined in Data.HList.HList Methods (==) :: HList '[] -> HList '[] -> Bool # (/=) :: HList '[] -> HList '[] -> Bool #
(Data x, Data (HList xs), TypeablePolyK (x ': xs), Typeable (HList (x ': xs))) => Data (HList (x ': xs)) Source #
Instance details Defined in Data.HList.Data Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> HList (x ': xs) -> c (HList (x ': xs)) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (HList (x ': xs)) # toConstr :: HList (x ': xs) -> Constr # dataTypeOf :: HList (x ': xs) -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (HList (x ': xs))) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (HList (x ': xs))) # gmapT :: (forall b. Data b => b -> b) -> HList (x ': xs) -> HList (x ': xs) # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> HList (x ': xs) -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> HList (x ': xs) -> r # gmapQ :: (forall d. Data d => d -> u) -> HList (x ': xs) -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> HList (x ': xs) -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> HList (x ': xs) -> m (HList (x ': xs)) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> HList (x ': xs) -> m (HList (x ': xs)) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> HList (x ': xs) -> m (HList (x ': xs)) #
Typeable (HList ('[] :: [Type])) => Data (HList ('[] :: [Type])) Source #
Instance details Defined in Data.HList.Data Methods gfoldl :: (forall d b. Data d => c (d -> b) -> d -> c b) -> (forall g. g -> c g) -> HList '[] -> c (HList '[]) # gunfold :: (forall b r. Data b => c (b -> r) -> c r) -> (forall r. r -> c r) -> Constr -> c (HList '[]) # toConstr :: HList '[] -> Constr # dataTypeOf :: HList '[] -> DataType # dataCast1 :: Typeable t => (forall d. Data d => c (t d)) -> Maybe (c (HList '[])) # dataCast2 :: Typeable t => (forall d e. (Data d, Data e) => c (t d e)) -> Maybe (c (HList '[])) # gmapT :: (forall b. Data b => b -> b) -> HList '[] -> HList '[] # gmapQl :: (r -> r' -> r) -> r -> (forall d. Data d => d -> r') -> HList '[] -> r # gmapQr :: forall r r'. (r' -> r -> r) -> r -> (forall d. Data d => d -> r') -> HList '[] -> r # gmapQ :: (forall d. Data d => d -> u) -> HList '[] -> [u] # gmapQi :: Int -> (forall d. Data d => d -> u) -> HList '[] -> u # gmapM :: Monad m => (forall d. Data d => d -> m d) -> HList '[] -> m (HList '[]) # gmapMp :: MonadPlus m => (forall d. Data d => d -> m d) -> HList '[] -> m (HList '[]) # gmapMo :: MonadPlus m => (forall d. Data d => d -> m d) -> HList '[] -> m (HList '[]) #
(Ord x, Ord (HList xs)) => Ord (HList (x ': xs)) Source #
Instance details Defined in Data.HList.HList Methods compare :: HList (x ': xs) -> HList (x ': xs) -> Ordering # (<) :: HList (x ': xs) -> HList (x ': xs) -> Bool # (<=) :: HList (x ': xs) -> HList (x ': xs) -> Bool # (>) :: HList (x ': xs) -> HList (x ': xs) -> Bool # (>=) :: HList (x ': xs) -> HList (x ': xs) -> Bool # max :: HList (x ': xs) -> HList (x ': xs) -> HList (x ': xs) # min :: HList (x ': xs) -> HList (x ': xs) -> HList (x ': xs) #
Ord (HList ('[] :: [Type])) Source #
Instance details Defined in Data.HList.HList Methods compare :: HList '[] -> HList '[] -> Ordering # (<) :: HList '[] -> HList '[] -> Bool # (<=) :: HList '[] -> HList '[] -> Bool # (>) :: HList '[] -> HList '[] -> Bool # (>=) :: HList '[] -> HList '[] -> Bool # max :: HList '[] -> HList '[] -> HList '[] # min :: HList '[] -> HList '[] -> HList '[] #
(HProxies l, Read e, HSequence ReadP (ReadP e ': readP_l) (e ': l), HMapCxt HList ReadElement (AddProxy l) readP_l) => Read (HList (e ': l)) Source #
Instance details Defined in Data.HList.HList Methods readsPrec :: Int -> ReadS (HList (e ': l)) # readList :: ReadS [HList (e ': l)] # readPrec :: ReadPrec (HList (e ': l)) # readListPrec :: ReadPrec [HList (e ': l)] #
Read (HList ('[] :: [Type])) Source #
Instance details Defined in Data.HList.HList Methods readsPrec :: Int -> ReadS (HList '[]) # readList :: ReadS [HList '[]] # readPrec :: ReadPrec (HList '[]) # readListPrec :: ReadPrec [HList '[]] #
(Show e, Show (HList l)) => Show (HList (e ': l)) Source #
Instance details Defined in Data.HList.HList Methods showsPrec :: Int -> HList (e ': l) -> ShowS # show :: HList (e ': l) -> String # showList :: [HList (e ': l)] -> ShowS #
Show (HList ('[] :: [Type])) Source #
Instance details Defined in Data.HList.HList Methods showsPrec :: Int -> HList '[] -> ShowS # show :: HList '[] -> String # showList :: [HList '[]] -> ShowS #
(Ix x, Ix (HList xs)) => Ix (HList (x ': xs)) Source #
Instance details Defined in Data.HList.HList Methods range :: (HList (x ': xs), HList (x ': xs)) -> [HList (x ': xs)] # index :: (HList (x ': xs), HList (x ': xs)) -> HList (x ': xs) -> Int # unsafeIndex :: (HList (x ': xs), HList (x ': xs)) -> HList (x ': xs) -> Int # inRange :: (HList (x ': xs), HList (x ': xs)) -> HList (x ': xs) -> Bool # rangeSize :: (HList (x ': xs), HList (x ': xs)) -> Int # unsafeRangeSize :: (HList (x ': xs), HList (x ': xs)) -> Int #
Ix (HList ('[] :: [Type])) Source #
Instance details Defined in Data.HList.HList Methods range :: (HList '[], HList '[]) -> [HList '[]] # index :: (HList '[], HList '[]) -> HList '[] -> Int # unsafeIndex :: (HList '[], HList '[]) -> HList '[] -> Int # inRange :: (HList '[], HList '[]) -> HList '[] -> Bool # rangeSize :: (HList '[], HList '[]) -> Int # unsafeRangeSize :: (HList '[], HList '[]) -> Int #
(HZip HList a a aa, HMapCxt HList UncurryMappend aa a) => Semigroup (HList a) Source #
Instance details Defined in Data.HList.HList Methods (<>) :: HList a -> HList a -> HList a # sconcat :: NonEmpty (HList a) -> HList a # stimes :: Integral b => b -> HList a -> HList a #
(HProxies a, HMapCxt HList ConstMempty (AddProxy a) a, HZip HList a a aa, HMapCxt HList UncurryMappend aa a) => Monoid (HList a) Source #	Analogous to the Monoid instance for tuples `>>>` `import Data.Monoid``>>>` `mempty :: HList '[(), All, [Int]]`H[(),All {getAll = True},[]] `>>>` `mappend (hBuild "a") (hBuild "b") :: HList '[String]`H["ab"]
Instance details Defined in Data.HList.HList Methods mempty :: HList a # mappend :: HList a -> HList a -> HList a # mconcat :: [HList a] -> HList a #
(TypeRepsList (HList xs), Typeable x) => TypeRepsList (HList (x ': xs)) Source #
Instance details Defined in Data.HList.Data Methods typeRepsList :: HList (x ': xs) -> [TypeRep] Source #
TypeRepsList (HList ('[] :: [Type])) Source #
Instance details Defined in Data.HList.Data Methods typeRepsList :: HList '[] -> [TypeRep] Source #
(HDeleteAtHNat n l, HType2HNat e l n, l' ~ HDeleteAtHNatR n l) => HDeleteAtLabel HList (e :: Type) l l' Source #	should this instead delete the first element of that type?
Instance details Defined in Data.HList.HTypeIndexed Methods hDeleteAtLabel :: Label e -> HList l -> HList l' Source #
(HEq e1 e b, HDeleteManyCase b e1 e l l1) => HDeleteMany (e1 :: Type) (HList (e ': l)) (HList l1) Source #
Instance details Defined in Data.HList.HTypeIndexed Methods hDeleteMany :: Proxy e1 -> HList (e ': l) -> HList l1 Source #
HProject (HList l) (HList ('[] :: [Type])) Source #
Instance details Defined in Data.HList.HOccurs Methods hProject :: HList l -> HList '[] Source #
HAppendList l1 l2 => HAppend (HList l1) (HList l2) Source #
Instance details Defined in Data.HList.HList Methods hAppend :: HList l1 -> HList l2 -> HAppendR (HList l1) (HList l2) Source #
ApplyAB f e e' => ApplyAB (MapCar f) (e, HList l) (HList (e' ': l)) Source #
Instance details Defined in Data.HList.HList Methods applyAB :: MapCar f -> (e, HList l) -> HList (e' ': l) Source #
HInits1 ('[] :: [Type]) '[HList ('[] :: [Type])] Source #
Instance details Defined in Data.HList.HList Methods hInits1 :: HList '[] -> HList '[HList '[]] Source #
HTails ('[] :: [Type]) '[HList ('[] :: [Type])] Source #
Instance details Defined in Data.HList.HList Methods hTails :: HList '[] -> HList '[HList '[]] Source #
Apply (FHUProj sel ns) (HList l, Proxy ('HSucc n)) => Apply (Proxy 'False, FHUProj sel ns) (HList (e ': l), Proxy n) Source #
Instance details Defined in Data.HList.HArray Associated Types type ApplyR (Proxy 'False, FHUProj sel ns) (HList (e ': l), Proxy n) Source # Methods apply :: (Proxy 'False, FHUProj sel ns) -> (HList (e ': l), Proxy n) -> ApplyR (Proxy 'False, FHUProj sel ns) (HList (e ': l), Proxy n) Source #
Apply (Proxy 'True, FHUProj sel ns) (HList (e ': l), Proxy n) Source #
Instance details Defined in Data.HList.HArray Associated Types type ApplyR (Proxy 'True, FHUProj sel ns) (HList (e ': l), Proxy n) Source # Methods apply :: (Proxy 'True, FHUProj sel ns) -> (HList (e ': l), Proxy n) -> ApplyR (Proxy 'True, FHUProj sel ns) (HList (e ': l), Proxy n) Source #
(ch ~ Proxy (HBoolEQ sel (KMember n ns)), Apply (ch, FHUProj sel ns) (HList (e ': l), Proxy n)) => Apply (FHUProj sel ns) (HList (e ': l), Proxy n) Source #
Instance details Defined in Data.HList.HArray Associated Types type ApplyR (FHUProj sel ns) (HList (e ': l), Proxy n) Source # Methods apply :: FHUProj sel ns -> (HList (e ': l), Proxy n) -> ApplyR (FHUProj sel ns) (HList (e ': l), Proxy n) Source #
Apply (FHUProj sel ns) (HList ('[] :: [Type]), n) Source #
Instance details Defined in Data.HList.HArray Associated Types type ApplyR (FHUProj sel ns) (HList '[], n) Source # Methods apply :: FHUProj sel ns -> (HList '[], n) -> ApplyR (FHUProj sel ns) (HList '[], n) Source #
(HConcatFD as bs, HAppendFD a bs cs) => HConcatFD (HList a ': as) cs Source #
Instance details Defined in Data.HList.HList Methods hConcatFD :: HList (HList a ': as) -> HList cs Source #
(HInits1 xs ys, HMapCxt HList (FHCons2 x) ys ys', HMapCons x ys ~ ys', HMapTail ys' ~ ys) => HInits1 (x ': xs) (HList '[x] ': ys') Source #
Instance details Defined in Data.HList.HList Methods hInits1 :: HList (x ': xs) -> HList (HList '[x] ': ys') Source #
HTails xs ys => HTails (x ': xs) (HList (x ': xs) ': ys) Source #
Instance details Defined in Data.HList.HList Methods hTails :: HList (x ': xs) -> HList (HList (x ': xs) ': ys) Source #
HMapUnboxF xs us => HMapUnboxF (HList x ': xs) (RecordU x ': us) Source #
Instance details Defined in Data.HList.RecordU
(HList (x ': y) ~ z, HZip3 xs ys zs) => HZip3 (x ': xs) (HList y ': ys) (z ': zs) Source #
Instance details Defined in Data.HList.HZip Methods hZip3 :: HList (x ': xs) -> HList (HList y ': ys) -> HList (z ': zs) Source #
type HExtendR e (HList l) Source #
Instance details Defined in Data.HList.HList type HExtendR e (HList l) = HList (e ': l)
type HMapCons x (HList a ': b) Source #
Instance details Defined in Data.HList.HList type HMapCons x (HList a ': b) = HList (x ': a) ': HMapCons x b
type UnHList (HList a) Source #
Instance details Defined in Data.HList.HList type UnHList (HList a) = a
data HList ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList data HList ('[] :: [Type]) = HNil
type HAppendR (HList l1 :: Type) (HList l2 :: Type) Source #
Instance details Defined in Data.HList.HList type HAppendR (HList l1 :: Type) (HList l2 :: Type) = HList (HAppendListR l1 l2)
type ApplyR (Proxy 'False, FHUProj sel ns) (HList (e ': l), Proxy n) Source #
Instance details Defined in Data.HList.HArray type ApplyR (Proxy 'False, FHUProj sel ns) (HList (e ': l), Proxy n) = ApplyR (FHUProj sel ns) (HList l, Proxy ('HSucc n))
type ApplyR (Proxy 'True, FHUProj sel ns) (HList (e ': l), Proxy n) Source #
Instance details Defined in Data.HList.HArray type ApplyR (Proxy 'True, FHUProj sel ns) (HList (e ': l), Proxy n) = HJust (e, (HList l, Proxy ('HSucc n)))
type ApplyR (FHUProj sel ns) (HList ('[] :: [Type]), n) Source #
Instance details Defined in Data.HList.HArray type ApplyR (FHUProj sel ns) (HList ('[] :: [Type]), n) = HNothing
type ApplyR (FHUProj sel ns) (HList (e ': l), Proxy n) Source #
Instance details Defined in Data.HList.HArray type ApplyR (FHUProj sel ns) (HList (e ': l), Proxy n) = ApplyR (Proxy (HBoolEQ sel (KMember n ns)), FHUProj sel ns) (HList (e ': l), Proxy n)
type HMapTail (HList (a ': as) ': bs) Source #
Instance details Defined in Data.HList.HList type HMapTail (HList (a ': as) ': bs) = HList as ': HMapTail bs
data HList (x ': xs) Source #
Instance details Defined in Data.HList.HList data HList (x ': xs) = x `HCons` (HList xs)

class HProxiesFD (xs :: [*]) pxs | pxs -> xs, xs -> pxs where Source #

creates a HList of Proxies

Methods

hProxies :: HList pxs Source #

Instances

Instances details

HProxiesFD ('[] :: [Type]) ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hProxies :: HList '[] Source #
HProxiesFD xs pxs => HProxiesFD (x ': xs) (Proxy x ': pxs) Source #
Instance details Defined in Data.HList.HList Methods hProxies :: HList (Proxy x ': pxs) Source #

type HProxies xs = HProxiesFD xs (AddProxy xs) Source #

type family AddProxy (xs :: k) :: k Source #

Add Proxy to a type

>>> let x = undefined :: HList (AddProxy [Char,Int])
>>> :t x
x :: HList '[Proxy Char, Proxy Int]

Instances

Instances details

type AddProxy (x :: Type) Source #
Instance details Defined in Data.HList.HList type AddProxy (x :: Type) = Proxy x
type AddProxy ('[] :: [k]) Source #
Instance details Defined in Data.HList.HList type AddProxy ('[] :: [k]) = '[] :: [k]
type AddProxy (x ': xs :: [a]) Source #
Instance details Defined in Data.HList.HList type AddProxy (x ': xs :: [a]) = AddProxy x ': AddProxy xs

type family DropProxy (xs :: k) :: k Source #

inverse of AddProxy

Instances

Instances details

type DropProxy ('[] :: [k]) Source #
Instance details Defined in Data.HList.HList type DropProxy ('[] :: [k]) = '[] :: [k]
type DropProxy (Proxy x :: Type) Source #
Instance details Defined in Data.HList.HList type DropProxy (Proxy x :: Type) = x
type DropProxy (x ': xs :: [a]) Source #
Instance details Defined in Data.HList.HList type DropProxy (x ': xs :: [a]) = DropProxy x ': DropProxy xs

data ReadElement Source #

Constructors

ReadElement

Instances

Instances details

(y ~ ReadP x, Read x) => ApplyAB ReadElement (Proxy x) y Source #
Instance details Defined in Data.HList.HList Methods applyAB :: ReadElement -> Proxy x -> y Source #

Basic list functions

hHead :: HList (e ': l) -> e Source #

head

hTail :: HList (e ': l) -> HList l Source #

tail

hLast :: forall (l1 :: [Type]) e (l :: [Type]). HRevApp l1 ('[] :: [Type]) (e ': l) => HList l1 -> e Source #

last

class HInit xs where Source #

Associated Types

type HInitR xs :: [*] Source #

Methods

hInit :: HList xs -> HList (HInitR xs) Source #

Instances

Instances details

HInit (b ': c) => HInit (a ': (b ': c)) Source #
Instance details Defined in Data.HList.HList Associated Types type HInitR (a ': (b ': c)) :: [Type] Source # Methods hInit :: HList (a ': (b ': c)) -> HList (HInitR (a ': (b ': c))) Source #
HInit '[x] Source #
Instance details Defined in Data.HList.HList Associated Types type HInitR '[x] :: [Type] Source # Methods hInit :: HList '[x] -> HList (HInitR '[x]) Source #

type family HLength (x :: [k]) :: HNat Source #

Length, but see HLengthEq instead

Instances

Instances details

type HLength ('[] :: [k]) Source #
Instance details Defined in Data.HList.HList type HLength ('[] :: [k]) = 'HZero
type HLength (x ': xs :: [k]) Source #
Instance details Defined in Data.HList.HList type HLength (x ': xs :: [k]) = 'HSucc (HLength xs)

hLength :: HLengthEq l n => HList l -> Proxy n Source #

Append

type family HAppendListR (l1 :: [k]) (l2 :: [k]) :: [k] Source #

Instances

Instances details

type HAppendListR ('[] :: [k]) (l :: [k]) Source #
Instance details Defined in Data.HList.HList type HAppendListR ('[] :: [k]) (l :: [k]) = l
type HAppendListR (e ': l :: [k]) (l' :: [k]) Source #
Instance details Defined in Data.HList.HList type HAppendListR (e ': l :: [k]) (l' :: [k]) = e ': HAppendListR l l'

class HAppendList l1 l2 where Source #

Methods

hAppendList :: HList l1 -> HList l2 -> HList (HAppendListR l1 l2) Source #

the same as hAppend

Instances

Instances details

HAppendList ('[] :: [Type]) l2 Source #
Instance details Defined in Data.HList.HList Methods hAppendList :: HList '[] -> HList l2 -> HList (HAppendListR '[] l2) Source #
HAppendList l l' => HAppendList (x ': l) l' Source #
Instance details Defined in Data.HList.HList Methods hAppendList :: HList (x ': l) -> HList l' -> HList (HAppendListR (x ': l) l') Source #

Alternative append

append' :: [a] -> [a] -> [a] Source #

hAppend' below is implemented using the same idea

hAppend' :: HFoldr FHCons v l r => HList l -> v -> r Source #

Alternative implementation of hAppend. Demonstrates HFoldr

data FHCons Source #

Constructors

FHCons

Instances

Instances details

(x ~ (e, HList l), y ~ HList (e ': l)) => ApplyAB FHCons x y Source #
Instance details Defined in Data.HList.HList Methods applyAB :: FHCons -> x -> y Source #

Historical append

The original HList code is included below. In both cases we had to program the algorithm twice, at the term and the type levels.

The class HAppend

class HAppend l l' l'' | l l' -> l''
 where
  hAppend :: l -> l' -> l''

The instance following the normal append

instance HList l => HAppend HNil l l
 where
  hAppend HNil l = l

instance (HList l, HAppend l l' l'')
      => HAppend (HCons x l) l' (HCons x l'')
 where
  hAppend (HCons x l) l' = HCons x (hAppend l l')

Reversing HLists

type family HRevAppR (l1 :: [k]) (l2 :: [k]) :: [k] Source #

Instances

Instances details

type HRevAppR ('[] :: [k]) (l :: [k]) Source #
Instance details Defined in Data.HList.HList type HRevAppR ('[] :: [k]) (l :: [k]) = l
type HRevAppR (e ': l :: [a]) (l' :: [a]) Source #
Instance details Defined in Data.HList.HList type HRevAppR (e ': l :: [a]) (l' :: [a]) = HRevAppR l (e ': l')

class HRevApp l1 l2 l3 | l1 l2 -> l3 where Source #

Methods

hRevApp :: HList l1 -> HList l2 -> HList l3 Source #

Instances

Instances details

HRevApp ('[] :: [Type]) l2 l2 Source #
Instance details Defined in Data.HList.HList Methods hRevApp :: HList '[] -> HList l2 -> HList l2 Source #
HRevApp l (x ': l') z => HRevApp (x ': l) l' z Source #
Instance details Defined in Data.HList.HList Methods hRevApp :: HList (x ': l) -> HList l' -> HList z Source #

class HReverse xs sx | xs -> sx, sx -> xs where Source #

Methods

hReverse :: HList xs -> HList sx Source #

Instances

Instances details

(HRevApp xs ('[] :: [Type]) sx, HRevApp sx ('[] :: [Type]) xs) => HReverse xs sx Source #
Instance details Defined in Data.HList.HList Methods hReverse :: HList xs -> HList sx Source #

hReverse_ :: forall (l1 :: [Type]) (l3 :: [Type]). HRevApp l1 ('[] :: [Type]) l3 => HList l1 -> HList l3 Source #

a version of hReverse that does not allow the type information to flow backwards

A nicer notation for lists

hEnd :: HList l -> HList l Source #

Note:

x :: HList a: means: forall a. x :: HList a
hEnd x: means: exists a. x :: HList a

List termination

hBuild :: HBuild' '[] r => r Source #

Building lists

class HBuild' l r where Source #

Methods

hBuild' :: HList l -> r Source #

Instances

Instances details

HReverse l l' => HBuild' l (HList l') Source #
Instance details Defined in Data.HList.HList Methods hBuild' :: HList l -> HList l' Source #
(HReverse l lRev, HMapTaggedFn lRev l') => HBuild' l (Record l') Source #	This instance allows creating a Record with hBuild 3 `a` :: Record '[Tagged "x" Int, Tagged "y" Char]
Instance details Defined in Data.HList.Record Methods hBuild' :: HList l -> Record l' Source #
HBuild' (a ': l) r => HBuild' l (a -> r) Source #
Instance details Defined in Data.HList.HList Methods hBuild' :: HList l -> a -> r Source #
(HRevAppR l ('[] :: [Type]) ~ lRev, HExtendRs lRev (Proxy ('[] :: [Type])) ~ Proxy l1, l' ~ l1) => HBuild' l (Proxy l') Source #	see `hEndP`
Instance details Defined in Data.HList.Record Methods hBuild' :: HList l -> Proxy l' Source #

examples

The classes above allow the third (shortest) way to make a list (containing a,b,c) in this case

list = a `HCons` b `HCons` c `HCons` HNil
list = a .*. b .*. c .*. HNil
list = hEnd $ hBuild a b c

>>> let x = hBuild True in hEnd x
H[True]

>>> let x = hBuild True 'a' in hEnd x
H[True,'a']

>>> let x = hBuild True 'a' "ok" in hEnd x
H[True,'a',"ok"]

hBuild can also produce a Record, such that

hBuild x y ^. from unlabeled

can also be produced using

hEndR $ hBuild x y

historical

the show instance has since changed, but these uses of hBuild/hEnd still work

HList> let x = hBuild True in hEnd x
HCons True HNil

HList> let x = hBuild True 'a' in hEnd x
HCons True (HCons 'a' HNil)

HList> let x = hBuild True 'a' "ok" in hEnd x
HCons True (HCons 'a' (HCons "ok" HNil))

HList> hEnd (hBuild (Key 42) (Name "Angus") Cow (Price 75.5))
HCons (Key 42) (HCons (Name "Angus") (HCons Cow (HCons (Price 75.5) HNil)))

HList> hEnd (hBuild (Key 42) (Name "Angus") Cow (Price 75.5)) == angus
True

folds

foldr

Consume a heterogenous list.

class HFoldr f v (l :: [*]) r where Source #

Methods

hFoldr :: f -> v -> HList l -> r Source #

Instances

Instances details

v ~ v' => HFoldr f v ('[] :: [Type]) v' Source #
Instance details Defined in Data.HList.HList Methods hFoldr :: f -> v -> HList '[] -> v' Source #
(ApplyAB f (e, r) r', HFoldr f v l r) => HFoldr f v (e ': l) r' Source #	uses `ApplyAB` not `Apply`
Instance details Defined in Data.HList.HList Methods hFoldr :: f -> v -> HList (e ': l) -> r' Source #

class HScanr f z ls rs where Source #

Methods

hScanr :: f -> z -> HList ls -> HList rs Source #

Instances

Instances details

lz ~ '[z] => HScanr f z ('[] :: [Type]) lz Source #
Instance details Defined in Data.HList.HList Methods hScanr :: f -> z -> HList '[] -> HList lz Source #
(ApplyAB f (x, r) s, HScanr f z xs (r ': rs), srrs ~ (s ': (r ': rs))) => HScanr f z (x ': xs) srrs Source #
Instance details Defined in Data.HList.HList Methods hScanr :: f -> z -> HList (x ': xs) -> HList srrs Source #

class HFoldr1 f (l :: [*]) r where Source #

Methods

hFoldr1 :: f -> HList l -> r Source #

Instances

Instances details

(ApplyAB f (e, r) r', HFoldr1 f (e' ': l) r) => HFoldr1 f (e ': (e' ': l)) r' Source #	uses `ApplyAB` not `Apply`
Instance details Defined in Data.HList.HList Methods hFoldr1 :: f -> HList (e ': (e' ': l)) -> r' Source #
v ~ v' => HFoldr1 f '[v] v' Source #
Instance details Defined in Data.HList.HList Methods hFoldr1 :: f -> HList '[v] -> v' Source #

foldl

class HFoldl f (z :: *) xs (r :: *) where Source #

like foldl

>>> hFoldl (uncurry $ flip (:)) [] (1 `HCons` 2 `HCons` HNil)
[2,1]

Methods

hFoldl :: f -> z -> HList xs -> r Source #

Instances

Instances details

z ~ z' => HFoldl f z ('[] :: [Type]) z' Source #
Instance details Defined in Data.HList.HList Methods hFoldl :: f -> z -> HList '[] -> z' Source #
(zx ~ (z, x), ApplyAB f zx z', HFoldl f z' xs r) => HFoldl f z (x ': xs) r Source #
Instance details Defined in Data.HList.HList Methods hFoldl :: f -> z -> HList (x ': xs) -> r Source #

unfolds

unfold

Produce a heterogenous list. Uses the more limited Apply instead of App since that's all that is needed for uses of this function downstream. Those could in principle be re-written.

hUnfold :: forall f a (z :: [Type]). (HUnfoldFD f (ApplyR f a) z, Apply f a) => f -> a -> HList z Source #

type HUnfold p s = HUnfoldR p (ApplyR p s) Source #

type family HUnfoldR p res :: [*] Source #

Instances

Instances details

type HUnfoldR p HNothing Source #
Instance details Defined in Data.HList.HList type HUnfoldR p HNothing = '[] :: [Type]
type HUnfoldR p (HJust (e, s)) Source #
Instance details Defined in Data.HList.HList type HUnfoldR p (HJust (e, s)) = e ': HUnfoldR p (ApplyR p s)

type HUnfold' p res = HUnfoldFD p (ApplyR p res) (HUnfold p res) Source #

class HUnfoldFD p res z | p res -> z where Source #

Methods

hUnfold' :: p -> res -> HList z Source #

Instances

Instances details

HUnfoldFD p HNothing ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hUnfold' :: p -> HNothing -> HList '[] Source #
(Apply p s, HUnfoldFD p (ApplyR p s) z) => HUnfoldFD p (HJust (e, s)) (e ': z) Source #
Instance details Defined in Data.HList.HList Methods hUnfold' :: p -> HJust (e, s) -> HList (e ': z) Source #

replicate

class HLengthEq es n => HReplicateFD (n :: HNat) e es | n e -> es, es -> n where Source #

Sometimes the result type can fix the type of the first argument:

>>> hReplicate Proxy () :: HList '[ (), (), () ]
H[(),(),()]

However, with HReplicate all elements must have the same type, so it may be easier to use HList2List:

>>> list2HList (repeat 3) :: Maybe (HList [Int, Int, Int])
Just H[3,3,3]

Methods

hReplicate :: Proxy n -> e -> HList es Source #

Instances

Instances details

HReplicateFD 'HZero e ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hReplicate :: Proxy 'HZero -> e -> HList '[] Source #
(HReplicateFD n e es, e ~ e') => HReplicateFD ('HSucc n) e (e' ': es) Source #
Instance details Defined in Data.HList.HList Methods hReplicate :: Proxy ('HSucc n) -> e -> HList (e' ': es) Source #

type HReplicate n e = HReplicateFD n e (HReplicateR n e) Source #

type family HReplicateR (n :: HNat) (e :: k) :: [k] Source #

would be associated with HReplicate except we want it to work with e of any kind, not just * that you can put into a HList. An "inverse" of HLength

Instances

Instances details

type HReplicateR 'HZero (e :: k) Source #
Instance details Defined in Data.HList.HList type HReplicateR 'HZero (e :: k) = '[] :: [k]
type HReplicateR ('HSucc n) (e :: k) Source #
Instance details Defined in Data.HList.HList type HReplicateR ('HSucc n) (e :: k) = e ': HReplicateR n e

class HLengthEq r n => HReplicateF (n :: HNat) f z r | r -> n where Source #

HReplicate produces lists that can be converted to ordinary lists

>>> let two = hSucc (hSucc hZero)
>>> let f = Fun' fromInteger :: Fun' Num Integer

>>> :t applyAB f
applyAB f :: Num b => Integer -> b

>>> hReplicateF two f 3
H[3,3]

>>> hReplicateF Proxy f 3 :: HList [Int, Double, Integer]
H[3,3.0,3]

Methods

hReplicateF :: HLengthEq r n => Proxy n -> f -> z -> HList r Source #

Instances

Instances details

HReplicateF 'HZero f z ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hReplicateF :: Proxy 'HZero -> f -> z -> HList '[] Source #
(ApplyAB f z fz, HReplicateF n f z r') => HReplicateF ('HSucc n) f z (fz ': r') Source #
Instance details Defined in Data.HList.HList Methods hReplicateF :: Proxy ('HSucc n) -> f -> z -> HList (fz ': r') Source #

iterate

class HLengthEq r n => HIterate n f z r where Source #

This function behaves like iterate, with an extra argument to help figure out the result length

>>> let three = hSucc (hSucc (hSucc hZero))
>>> let f = Fun Just :: Fun '() Maybe

>>> :t applyAB f
applyAB f :: a -> Maybe a

f is applied to different types:

>>> hIterate three f ()
H[(),Just (),Just (Just ())]

It is also possible to specify the length later on, as done with Prelude.iterate

>>> let take3 x | _ <- hLength x `asTypeOf` three = x
>>> take3 $ hIterate Proxy f ()
H[(),Just (),Just (Just ())]

Methods

hIterate :: HLengthEq r n => Proxy n -> f -> z -> HList r Source #

Instances

Instances details

HIterate 'HZero f z ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hIterate :: Proxy 'HZero -> f -> z -> HList '[] Source #
(ApplyAB f z z', HIterate n f z' r', z ~ z_) => HIterate ('HSucc n) f z (z_ ': r') Source #
Instance details Defined in Data.HList.HList Methods hIterate :: Proxy ('HSucc n) -> f -> z -> HList (z_ ': r') Source #

concat

type HConcat xs = HConcatFD xs (HConcatR xs) Source #

Like concat but for HLists of HLists.

Works in ghci... puzzling as what is different in doctest (it isn't -XExtendedDefaultRules)

>>> let a = hEnd $ hBuild 1 2 3
>>> let b = hEnd $ hBuild 'a' "abc"
>>> hConcat $ hBuild a b
H[1,2,3,'a',"abc"]

hConcat :: HConcat xs => HList xs -> HList (HConcatR xs) Source #

type family HConcatR (a :: [*]) :: [*] Source #

Instances

Instances details

type HConcatR ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList type HConcatR ('[] :: [Type]) = '[] :: [Type]
type HConcatR (x ': xs) Source #
Instance details Defined in Data.HList.HList type HConcatR (x ': xs) = HAppendListR (UnHList x) (HConcatR xs)

type family UnHList a :: [*] Source #

Instances

Instances details

type UnHList (HList a) Source #
Instance details Defined in Data.HList.HList type UnHList (HList a) = a

class HConcatFD xxs xs | xxs -> xs where Source #

Methods

hConcatFD :: HList xxs -> HList xs Source #

Instances

Instances details

HConcatFD ('[] :: [Type]) ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hConcatFD :: HList '[] -> HList '[] Source #
(HConcatFD as bs, HAppendFD a bs cs) => HConcatFD (HList a ': as) cs Source #
Instance details Defined in Data.HList.HList Methods hConcatFD :: HList (HList a ': as) -> HList cs Source #

class HAppendFD a b ab | a b -> ab where Source #

Methods

hAppendFD :: HList a -> HList b -> HList ab Source #

Instances

Instances details

HAppendFD ('[] :: [Type]) b b Source #
Instance details Defined in Data.HList.HList Methods hAppendFD :: HList '[] -> HList b -> HList b Source #
HAppendFD as bs cs => HAppendFD (a ': as) bs (a ': cs) Source #
Instance details Defined in Data.HList.HList Methods hAppendFD :: HList (a ': as) -> HList bs -> HList (a ': cs) Source #

traversing HLists

producing HList

map

It could be implemented with hFoldr, as we show further below

newtype HMap f Source #

hMap is written such that the length of the result list can be determined from the length of the argument list (and the other way around). Similarly, the type of the elements of the list is propagated in both directions too.

>>> :set -XNoMonomorphismRestriction
>>> let xs = 1 .*. 'c' .*. HNil
>>> :t hMap (HJust ()) xs
hMap (HJust ()) xs :: Num y => HList '[HJust y, HJust Char]

These 4 examples show that the constraint on the length (2 in this case) can be applied before or after the hMap. That inference is independent of the direction that type information is propagated for the individual elements.

>>> let asLen2 xs = xs `asTypeOf` (undefined :: HList '[a,b])

>>> let lr xs = asLen2 (applyAB (HMap HRead) xs)
>>> let ls xs = asLen2 (applyAB (HMap HShow) xs)
>>> let rl xs = applyAB (HMap HRead) (asLen2 xs)
>>> let sl xs = applyAB (HMap HShow) (asLen2 xs)

>>> :t lr
lr
  :: (Read ..., Read ...) => HList '[String, String] -> HList '[..., ...]

>>> :t rl
rl
  :: (Read ..., Read ...) => HList '[String, String] -> HList '[..., ...]

>>> :t ls
ls
  :: (Show ..., Show ...) => HList '[..., ...] -> HList '[String, String]

>>> :t sl
sl
  :: (Show ..., Show ...) => HList '[..., ...] -> HList '[String, String]

Constructors

HMap f

Instances

Instances details

(HMapCxt r f a b, as ~ r a, bs ~ r b) => ApplyAB (HMap f) as bs Source #
Instance details Defined in Data.HList.HList Methods applyAB :: HMap f -> as -> bs Source #

hMap :: forall (a :: [Type]) (b :: [Type]) r f. (SameLength' a b, SameLength' b a, HMapAux r f a b) => f -> r a -> r b Source #

hMapL :: forall (a :: [Type]) (b :: [Type]) f. (SameLength' a b, SameLength' b a, HMapAux HList f a b) => f -> HList a -> HList b Source #

hMap constrained to HList

newtype HMapL f Source #

Constructors

HMapL f

Instances

Instances details

(HMapCxt HList f a b, as ~ HList a, bs ~ HList b) => ApplyAB (HMapL f) as bs Source #
Instance details Defined in Data.HList.HList Methods applyAB :: HMapL f -> as -> bs Source #

class (SameLength a b, HMapAux r f a b) => HMapCxt r f a b Source #

Instances

Instances details

(SameLength a b, HMapAux r f a b) => HMapCxt r f a b Source #
Instance details Defined in Data.HList.HList

class HMapAux (r :: [*] -> *) f (x :: [*]) (y :: [*]) where Source #

Methods

hMapAux :: SameLength x y => f -> r x -> r y Source #

Instances

Instances details

HMapAux HList (HFmap f) x y => HMapAux Record f x y Source #
Instance details Defined in Data.HList.Record Methods hMapAux :: f -> Record x -> Record y Source #
HMapAux Variant f xs ys => HMapAux TIC f xs ys Source #
Instance details Defined in Data.HList.TIC Methods hMapAux :: f -> TIC xs -> TIC ys Source #
(ApplyAB f (GetElemTy x) (GetElemTy y), IArray UArray (GetElemTy y), IArray UArray (GetElemTy x)) => HMapAux RecordU f x y Source #
Instance details Defined in Data.HList.RecordU Methods hMapAux :: f -> RecordU x -> RecordU y Source #
HMapAux HList f ('[] :: [Type]) ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hMapAux :: f -> HList '[] -> HList '[] Source #
(ApplyAB f e e', HMapAux HList f l l', SameLength l l') => HMapAux HList f (e ': l) (e' ': l') Source #
Instance details Defined in Data.HList.HList Methods hMapAux :: f -> HList (e ': l) -> HList (e' ': l') Source #
(ApplyAB f te te', HMapCxt Variant f (l ': ls) (l' ': ls')) => HMapAux Variant f (te ': (l ': ls)) (te' ': (l' ': ls')) Source #
Instance details Defined in Data.HList.Variant Methods hMapAux :: f -> Variant (te ': (l ': ls)) -> Variant (te' ': (l' ': ls')) Source #
ApplyAB f te te' => HMapAux Variant f '[te] '[te'] Source #
Instance details Defined in Data.HList.Variant Methods hMapAux :: f -> Variant '[te] -> Variant '[te'] Source #

alternative implementation

currently broken

newtype MapCar f Source #

Constructors

MapCar f

Instances

Instances details

ApplyAB f e e' => ApplyAB (MapCar f) (e, HList l) (HList (e' ': l)) Source #
Instance details Defined in Data.HList.HList Methods applyAB :: MapCar f -> (e, HList l) -> HList (e' ': l) Source #

hMapMapCar :: HFoldr (MapCar f) (HList '[]) l l' => f -> HList l -> l' Source #

Same as hMap only a different implementation.

`appEndo . mconcat . map Endo`

hComposeList :: HFoldr Comp (a -> a) l (t -> a) => HList l -> t -> a Source #

>>> let xs = length .*. (+1) .*. (*2) .*. HNil
>>> hComposeList xs "abc"
8

sequence

class (Applicative m, SameLength a b) => HSequence m a b | a -> b, m b -> a where Source #

A heterogeneous version of

sequenceA :: (Applicative m) => [m a] -> m [a]

Only now we operate on heterogeneous lists, where different elements may have different types a. In the argument list of monadic values (m a_i), although a_i may differ, the monad m must be the same for all elements. That's why we needed Data.HList.TypeCastGeneric2 (currently (~)). The typechecker will complain if we attempt to use hSequence on a HList of monadic values with different monads.

The hSequence problem was posed by Matthias Fischmann in his message on the Haskell-Cafe list on Oct 8, 2006

http://www.haskell.org/pipermail/haskell-cafe/2006-October/018708.html

http://www.haskell.org/pipermail/haskell-cafe/2006-October/018784.html

Maybe

>>> hSequence $ Just (1 :: Integer) `HCons` (Just 'c') `HCons` HNil
Just H[1,'c']

>>> hSequence $  return 1 `HCons` Just  'c' `HCons` HNil
Just H[1,'c']

List

>>> hSequence $ [1] `HCons` ['c'] `HCons` HNil
[H[1,'c']]

Methods

hSequence :: HList a -> m (HList b) Source #

Instances

Instances details

Applicative m => HSequence m ('[] :: [Type]) ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hSequence :: HList '[] -> m (HList '[]) Source #
(m1 ~ m, Applicative m, HSequence m as bs) => HSequence m (m1 a ': as) (a ': bs) Source #
Instance details Defined in Data.HList.HList Methods hSequence :: HList (m1 a ': as) -> m (HList (a ': bs)) Source #

alternative implementation

hSequence2 :: forall f (l :: [Type]) a. (Applicative f, HFoldr (LiftA2 FHCons) (f (HList ('[] :: [Type]))) l (f a)) => HList l -> f a Source #

hSequence2 is not recommended over hSequence since it possibly doesn't allow inferring argument types from the result types. Otherwise this version should do exactly the same thing.

The DataKinds version needs a little help to find the type of the return HNil, unlike the original version, which worked just fine as

hSequence l = hFoldr ConsM (return HNil) l

producing homogenous lists

map (no sequencing)

This one we implement via hFoldr

newtype Mapcar f Source #

Constructors

Mapcar f

Instances

Instances details

(l ~ [e'], ApplyAB f e e', el ~ (e, l)) => ApplyAB (Mapcar f) el l Source #
Instance details Defined in Data.HList.HList Methods applyAB :: Mapcar f -> el -> l Source #

type HMapOut f l e = HFoldr (Mapcar f) [e] l [e] Source #

hMapOut :: forall f e l. HMapOut f l e => f -> HList l -> [e] Source #

compare hMapOut f with hList2List . hMap f

mapM

hMapM :: (Monad m, HMapOut f l (m e)) => f -> HList l -> [m e] Source #

mapM :: forall b m a. (Monad m) => (a -> m b) -> [a] -> m [b]

Likewise for mapM_.

See hSequence if the result list should also be heterogenous.

hMapM_ :: (Monad m, HMapOut f l (m ())) => f -> HList l -> m () Source #

GHC doesn't like its own type.

hMapM_ :: forall m a f e. (Monad m, HMapOut f a (m e)) => f -> a -> m ()

Without explicit type signature, it's Ok. Sigh. Anyway, Hugs does insist on a better type. So we restrict as follows:

Ensure a list to contain HNats only

type family HNats (l :: [*]) :: [HNat] Source #

We do so constructively, converting the HList whose elements are Proxy HNat to [HNat]. The latter kind is unpopulated and is present only at the type level.

Instances

Instances details

type HNats ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList type HNats ('[] :: [Type]) = '[] :: [HNat]
type HNats (Proxy n ': l) Source #
Instance details Defined in Data.HList.HList type HNats (Proxy n ': l) = n ': HNats l

hNats :: HList l -> Proxy (HNats l) Source #

Membership tests

class HMember (e1 :: k) (l :: [k]) (b :: Bool) | e1 l -> b Source #

Check to see if an HList contains an element with a given type This is a type-level only test

Instances

Instances details

HMember (e1 :: k) ('[] :: [k]) 'False Source #
Instance details Defined in Data.HList.HList
(HEq e1 e b, HMember' b e1 l br) => HMember (e1 :: a) (e ': l :: [a]) br Source #
Instance details Defined in Data.HList.HList

class HMember' (b0 :: Bool) (e1 :: k) (l :: [k]) (b :: Bool) | b0 e1 l -> b Source #

Instances

Instances details

HMember e1 l br => HMember' 'False (e1 :: k) (l :: [k]) br Source #
Instance details Defined in Data.HList.HList
HMember' 'True (e1 :: k) (l :: [k]) 'True Source #
Instance details Defined in Data.HList.HList

type family HMemberP pred e1 (l :: [*]) :: Bool Source #

The following is a similar type-only membership test It uses the user-supplied curried type equality predicate pred

Instances

Instances details

type HMemberP pred e1 ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList type HMemberP pred e1 ('[] :: [Type]) = 'False
type HMemberP pred e1 (e ': l) Source #
Instance details Defined in Data.HList.HList type HMemberP pred e1 (e ': l) = HMemberP' pred e1 l (ApplyR pred (e1, e))

type family HMemberP' pred e1 (l :: [*]) pb :: Bool Source #

Instances

Instances details

type HMemberP' pred e1 l (Proxy 'False) Source #
Instance details Defined in Data.HList.HList type HMemberP' pred e1 l (Proxy 'False) = HMemberP pred e1 l
type HMemberP' pred e1 l (Proxy 'True) Source #
Instance details Defined in Data.HList.HList type HMemberP' pred e1 l (Proxy 'True) = 'True

hMember :: HMember e l b => Proxy e -> Proxy l -> Proxy b Source #

Another type-level membership test

class HMemberM (e1 :: k) (l :: [k]) (r :: Maybe [k]) | e1 l -> r Source #

Check to see if an element e occurs in a list l If not, return 'Nothing If the element does occur, return 'Just l1 where l1 is a type-level list without e

Instances

Instances details

HMemberM (e1 :: k) ('[] :: [k]) ('Nothing :: Maybe [k]) Source #
Instance details Defined in Data.HList.HList
(HEq e1 e b, HMemberM1 b e1 (e ': l) res) => HMemberM (e1 :: a) (e ': l :: [a]) (res :: Maybe [a]) Source #
Instance details Defined in Data.HList.HList

class HMemberM1 (b :: Bool) (e1 :: k) (l :: [k]) (r :: Maybe [k]) | b e1 l -> r Source #

Instances

Instances details

(HMemberM e1 l r, HMemberM2 r e1 (e ': l) res) => HMemberM1 'False (e1 :: a) (e ': l :: [a]) (res :: Maybe [a]) Source #
Instance details Defined in Data.HList.HList
HMemberM1 'True (e1 :: k) (e ': l :: [k]) ('Just l :: Maybe [k]) Source #
Instance details Defined in Data.HList.HList

class HMemberM2 (b :: Maybe [k]) (e1 :: k) (l :: [k]) (r :: Maybe [k]) | b e1 l -> r Source #

Instances

Instances details

HMemberM2 ('Nothing :: Maybe [k]) (e1 :: k) (l :: [k]) ('Nothing :: Maybe [k]) Source #
Instance details Defined in Data.HList.HList
HMemberM2 ('Just l1 :: Maybe [a]) (e1 :: a) (e ': l :: [a]) ('Just (e ': l1) :: Maybe [a]) Source #
Instance details Defined in Data.HList.HList

Staged equality for lists

removed. use Typeable instead

Find an element in a set based on HEq

class HFind1 e l l n => HFind (e :: k) (l :: [k]) (n :: HNat) | e l -> n Source #

It is a pure type-level operation

Instances

Instances details

HFind1 e l l n => HFind (e :: k) (l :: [k]) n Source #
Instance details Defined in Data.HList.HList

class HFind1 (e :: k) (l :: [k]) (l0 :: [k]) (n :: HNat) | e l -> n Source #

Instances

Instances details

Fail (FieldNotFound e1 l0) => HFind1 (e1 :: k) ('[] :: [k]) (l0 :: [k]) 'HZero Source #
Instance details Defined in Data.HList.HList
(HEq e1 e2 b, HFind2 b e1 l l0 n) => HFind1 (e1 :: a) (e2 ': l :: [a]) (l0 :: [a]) n Source #
Instance details Defined in Data.HList.HList

class HFind2 (b :: Bool) (e :: k) (l :: [k]) (l0 :: [k]) (n :: HNat) | b e l -> n Source #

Instances

Instances details

HFind2 'True (e :: k) (l :: [k]) (l0 :: [k]) 'HZero Source #
Instance details Defined in Data.HList.HList
HFind1 e l l0 n => HFind2 'False (e :: k) (l :: [k]) (l0 :: [k]) ('HSucc n) Source #
Instance details Defined in Data.HList.HList

Membership test based on type equality

class HTMember e (l :: [*]) (b :: Bool) | e l -> b Source #

could be an associated type if HEq had one

Instances

Instances details

HTMember (e :: k) ('[] :: [Type]) 'False Source #
Instance details Defined in Data.HList.HList
(HEq e e' b, HTMember e l b', HOr b b' ~ b'') => HTMember (e :: Type) (e' ': l) b'' Source #
Instance details Defined in Data.HList.HList

hTMember :: HTMember e l b => e -> HList l -> Proxy b Source #

Intersection based on HTMember

class HTIntersect l1 l2 l3 | l1 l2 -> l3 where Source #

Methods

hTIntersect :: HList l1 -> HList l2 -> HList l3 Source #

Like intersect

Instances

Instances details

HTIntersect ('[] :: [Type]) l ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hTIntersect :: HList '[] -> HList l -> HList '[] Source #
(HTMember h l1 b, HTIntersectBool b h t l1 l2) => HTIntersect (h ': t) l1 l2 Source #
Instance details Defined in Data.HList.HList Methods hTIntersect :: HList (h ': t) -> HList l1 -> HList l2 Source #

class HTIntersectBool (b :: Bool) h t l1 l2 | b h t l1 -> l2 where Source #

Methods

hTIntersectBool :: Proxy b -> h -> HList t -> HList l1 -> HList l2 Source #

Instances

Instances details

HTIntersect t l1 l2 => HTIntersectBool 'False h t l1 l2 Source #
Instance details Defined in Data.HList.HList Methods hTIntersectBool :: Proxy 'False -> h -> HList t -> HList l1 -> HList l2 Source #
HTIntersect t l1 l2 => HTIntersectBool 'True h t l1 (h ': l2) Source #
Instance details Defined in Data.HList.HList Methods hTIntersectBool :: Proxy 'True -> h -> HList t -> HList l1 -> HList (h ': l2) Source #

Convert between heterogeneous lists and homogeneous ones

class HList2List l e | l -> e where Source #

hMapOut id is similar, except this function is restricted to HLists that actually contain a value (so the list produced will be nonempty). This restriction allows adding a functional dependency, which means that less type annotations can be necessary.

Methods

hList2List :: HList l -> [e] Source #

list2HListSuffix :: [e] -> Maybe (HList l, [e]) Source #

Instances

Instances details

HList2List (e' ': l) e => HList2List (e ': (e' ': l)) e Source #
Instance details Defined in Data.HList.HList Methods hList2List :: HList (e ': (e' ': l)) -> [e] Source # list2HListSuffix :: [e] -> Maybe (HList (e ': (e' ': l)), [e]) Source #
HList2List '[e] e Source #
Instance details Defined in Data.HList.HList Methods hList2List :: HList '[e] -> [e] Source # list2HListSuffix :: [e] -> Maybe (HList '[e], [e]) Source #

list2HList :: HList2List l e => [e] -> Maybe (HList l) Source #

listAsHList :: forall (l1 :: [Type]) e1 (l2 :: [Type]) e2 p f. (HList2List l1 e1, HList2List l2 e2, Choice p, Applicative f) => p (HList l2) (f (HList l1)) -> p [e2] (f [e1]) Source #

Prism [s] [t] (HList s) (HList t)

listAsHList' :: forall (l :: [Type]) e p f. (HList2List l e, Choice p, Applicative f) => p (HList l) (f (HList l)) -> p [e] (f [e]) Source #

Prism' [a] (HList s)

where s ~ HReplicateR n a

With `HMaybe`

Turn list in a list of justs

class FromHJustR (ToHJustR l) ~ l => ToHJust l where Source #

the same as map Just

>>> toHJust (2 .*. 'a' .*. HNil)
H[HJust 2,HJust 'a']

>>> toHJust2 (2 .*. 'a' .*. HNil)
H[HJust 2,HJust 'a']

Associated Types

type ToHJustR l :: [*] Source #

Methods

toHJust :: HList l -> HList (ToHJustR l) Source #

Instances

Instances details

ToHJust ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Associated Types type ToHJustR '[] :: [Type] Source # Methods toHJust :: HList '[] -> HList (ToHJustR '[]) Source #
ToHJust l => ToHJust (e ': l) Source #
Instance details Defined in Data.HList.HList Associated Types type ToHJustR (e ': l) :: [Type] Source # Methods toHJust :: HList (e ': l) -> HList (ToHJustR (e ': l)) Source #

toHJust2 :: (HMapCxt r (HJust ()) a b, ToHJust a, b ~ ToHJustR a) => r a -> r b Source #

alternative implementation. The Apply instance is in Data.HList.FakePrelude. A longer type could be inferred.

Extract justs from list of maybes

class FromHJustR (ToHJustR l) ~ l => FromHJust l where Source #

Associated Types

type FromHJustR l :: [*] Source #

Methods

fromHJust :: HList l -> HList (FromHJustR l) Source #

Instances

Instances details

FromHJust ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Associated Types type FromHJustR '[] :: [Type] Source # Methods fromHJust :: HList '[] -> HList (FromHJustR '[]) Source #
FromHJust l => FromHJust (HJust e ': l) Source #
Instance details Defined in Data.HList.HList Associated Types type FromHJustR (HJust e ': l) :: [Type] Source # Methods fromHJust :: HList (HJust e ': l) -> HList (FromHJustR (HJust e ': l)) Source #
FromHJust l => FromHJust (HNothing ': l) Source #
Instance details Defined in Data.HList.HList Associated Types type FromHJustR (HNothing ': l) :: [Type] Source # Methods fromHJust :: HList (HNothing ': l) -> HList (FromHJustR (HNothing ': l)) Source #

alternative implementation

fromHJust2 :: HMapCxt r HFromJust a b => r a -> r b Source #

This implementation is shorter.

data HFromJust Source #

Constructors

HFromJust

Instances

Instances details

hJustA ~ HJust a => ApplyAB HFromJust hJustA a Source #
Instance details Defined in Data.HList.HList Methods applyAB :: HFromJust -> hJustA -> a Source #

Annotated lists

data HAddTag t Source #

Constructors

HAddTag t

Instances

Instances details

et ~ (e, t) => ApplyAB (HAddTag t) e et Source #
Instance details Defined in Data.HList.HList Methods applyAB :: HAddTag t -> e -> et Source #

data HRmTag Source #

Constructors

HRmTag

Instances

Instances details

e' ~ e => ApplyAB HRmTag (e, t) e' Source #
Instance details Defined in Data.HList.HList Methods applyAB :: HRmTag -> (e, t) -> e' Source #

hAddTag :: forall (a :: [Type]) (b :: [Type]) r t. (SameLength' a b, SameLength' b a, HMapAux r (HAddTag t) a b) => t -> r a -> r b Source #

hRmTag :: forall (a :: [Type]) (b :: [Type]) r. (SameLength' a b, SameLength' b a, HMapAux r HRmTag a b) => r a -> r b Source #

hFlag :: forall (a :: [Type]) (b :: [Type]) r. (SameLength' a b, SameLength' b a, HMapAux r (HAddTag (Proxy 'True)) a b) => r a -> r b Source #

Annotate list with a type-level Boolean

hFlag :: HMapCxt (HAddTag (Proxy True)) l r => HList l -> HList r

Splitting by HTrue and HFalse

class HSplit l where Source #

Analogus to Data.List.partition snd. See also HPartition

>>> let (.=.) :: p x -> y -> Tagged x y; _ .=. y = Tagged y
>>> hSplit $ hTrue .=. 2 .*. hTrue .=. 3 .*. hFalse .=. 1 .*. HNil
(H[2,3],H[1])

it might make more sense to instead have LVPair Bool e instead of (e, Proxy Bool) since the former has the same runtime representation as e

Associated Types

type HSplitT l :: [*] Source #

type HSplitF l :: [*] Source #

Methods

hSplit :: HList l -> (HList (HSplitT l), HList (HSplitF l)) Source #

Instances

Instances details

HSplit ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Associated Types type HSplitT '[] :: [Type] Source # type HSplitF '[] :: [Type] Source # Methods hSplit :: HList '[] -> (HList (HSplitT '[]), HList (HSplitF '[])) Source #
HSplit l => HSplit ((e, Proxy 'False) ': l) Source #
Instance details Defined in Data.HList.HList Associated Types type HSplitT ((e, Proxy 'False) ': l) :: [Type] Source # type HSplitF ((e, Proxy 'False) ': l) :: [Type] Source # Methods hSplit :: HList ((e, Proxy 'False) ': l) -> (HList (HSplitT ((e, Proxy 'False) ': l)), HList (HSplitF ((e, Proxy 'False) ': l))) Source #
HSplit l => HSplit ((e, Proxy 'True) ': l) Source #
Instance details Defined in Data.HList.HList Associated Types type HSplitT ((e, Proxy 'True) ': l) :: [Type] Source # type HSplitF ((e, Proxy 'True) ': l) :: [Type] Source # Methods hSplit :: HList ((e, Proxy 'True) ': l) -> (HList (HSplitT ((e, Proxy 'True) ': l)), HList (HSplitF ((e, Proxy 'True) ': l))) Source #
HSplit l => HSplit (Tagged 'False e ': l) Source #
Instance details Defined in Data.HList.HList Associated Types type HSplitT (Tagged 'False e ': l) :: [Type] Source # type HSplitF (Tagged 'False e ': l) :: [Type] Source # Methods hSplit :: HList (Tagged 'False e ': l) -> (HList (HSplitT (Tagged 'False e ': l)), HList (HSplitF (Tagged 'False e ': l))) Source #
HSplit l => HSplit (Tagged 'True e ': l) Source #
Instance details Defined in Data.HList.HList Associated Types type HSplitT (Tagged 'True e ': l) :: [Type] Source # type HSplitF (Tagged 'True e ': l) :: [Type] Source # Methods hSplit :: HList (Tagged 'True e ': l) -> (HList (HSplitT (Tagged 'True e ': l)), HList (HSplitF (Tagged 'True e ': l))) Source #

Splitting by Length

class (HLengthEq xs n, HAppendList1 xs ys xsys) => HSplitAt (n :: HNat) xsys xs ys | n xsys -> xs ys, xs ys -> xsys, xs -> n where Source #

splitAt

setup

>>> let two = hSucc (hSucc hZero)
>>> let xsys = hEnd $ hBuild 1 2 3 4

If a length is explicitly provided, the resulting lists are inferred

>>> hSplitAt two xsys
(H[1,2],H[3,4])

>>> let sameLength_ :: SameLength a b => r a -> r b -> r a; sameLength_ = const
>>> let len2 x = x `sameLength_` HCons () (HCons () HNil)

If the first chunk of the list (a) has to be a certain length, the type of the Proxy argument can be inferred.

>>> case hSplitAt Proxy xsys of (a,b) -> (len2 a, b)
(H[1,2],H[3,4])

Methods

hSplitAt :: Proxy n -> HList xsys -> (HList xs, HList ys) Source #

Instances

Instances details

(HSplitAt1 ('[] :: [Type]) n xsys xs ys, HAppendList1 xs ys xsys, HLengthEq xs n) => HSplitAt n xsys xs ys Source #
Instance details Defined in Data.HList.HList Methods hSplitAt :: Proxy n -> HList xsys -> (HList xs, HList ys) Source #

class HSplitAt1 accum (n :: HNat) xsys xs ys | accum n xsys -> xs ys where Source #

helper for HSplitAt

Methods

hSplitAt1 :: HList accum -> Proxy n -> HList xsys -> (HList xs, HList ys) Source #

Instances

Instances details

HRevApp accum ('[] :: [Type]) xs => HSplitAt1 accum 'HZero ys xs ys Source #
Instance details Defined in Data.HList.HList Methods hSplitAt1 :: HList accum -> Proxy 'HZero -> HList ys -> (HList xs, HList ys) Source #
HSplitAt1 (b ': accum) n bs xs ys => HSplitAt1 accum ('HSucc n) (b ': bs) xs ys Source #
Instance details Defined in Data.HList.HList Methods hSplitAt1 :: HList accum -> Proxy ('HSucc n) -> HList (b ': bs) -> (HList xs, HList ys) Source #

class (SameLength' (HReplicateR n ()) xs, HLengthEq1 xs n, HLengthEq2 xs n) => HLengthEq (xs :: [*]) (n :: HNat) | xs -> n Source #

a better way to write HLength xs ~ n because:

it works properly with ghc-7.10 (probably another example of ghc bug #10009)
it works backwards a bit in that if n is known, then xs can be refined:

>>> undefined :: HLengthEq xs HZero => HList xs
H[]

Instances

Instances details

(SameLength' (HReplicateR n ()) xs, HLengthEq1 xs n, HLengthEq2 xs n) => HLengthEq xs n Source #
Instance details Defined in Data.HList.HList

class HLengthEq1 (xs :: [*]) n Source #

Instances

Instances details

xxs ~ ('[] :: [Type]) => HLengthEq1 xxs 'HZero Source #
Instance details Defined in Data.HList.HList
(HLengthEq xs n, xxs ~ (x ': xs)) => HLengthEq1 xxs ('HSucc n :: HNat) Source #
Instance details Defined in Data.HList.HList

class HLengthEq2 (xs :: [*]) n | xs -> n Source #

Instances

Instances details

zero ~ 'HZero => HLengthEq2 ('[] :: [Type]) (zero :: HNat) Source #
Instance details Defined in Data.HList.HList
(HLengthEq xs n, sn ~ 'HSucc n) => HLengthEq2 (x ': xs) (sn :: HNat) Source #
Instance details Defined in Data.HList.HList

class HLengthGe (xs :: [*]) (n :: HNat) Source #

HLengthGe xs n says that HLength xs >= n.

unlike the expression with a type family HLength, ghc assumes xs ~ (aFresh ': bFresh) when given a constraint HLengthGe xs (HSucc HZero)

Instances

Instances details

HLengthGe xxs 'HZero Source #
Instance details Defined in Data.HList.HList
(HLengthGe xs n, xxs ~ (x ': xs)) => HLengthGe xxs ('HSucc n) Source #
Instance details Defined in Data.HList.HList

class HStripPrefix xs xsys ys => HAppendList1 (xs :: [k]) (ys :: [k]) (xsys :: [k]) | xs ys -> xsys, xs xsys -> ys Source #

HAppendList1 xs ys xsys is the type-level way of saying xs ++ ys == xsys

used by HSplitAt

Instances

Instances details

HAppendList1 ('[] :: [k]) (ys :: [k]) (ys :: [k]) Source #
Instance details Defined in Data.HList.HList
HAppendList1 xs ys zs => HAppendList1 (x ': xs :: [a]) (ys :: [a]) (x ': zs :: [a]) Source #
Instance details Defined in Data.HList.HList

class HStripPrefix xs xsys ys | xs xsys -> ys Source #

analog of stripPrefix

Instances

Instances details

HStripPrefix ('[] :: [k2]) (ys :: k1) (ys :: k1) Source #
Instance details Defined in Data.HList.HList
(x' ~ x, HStripPrefix xs xsys ys) => HStripPrefix (x' ': xs :: [a]) (x ': xsys :: [a]) (ys :: k) Source #
Instance details Defined in Data.HList.HList

take

class HTake (n :: HNat) xs ys | n xs -> ys where Source #

Methods

hTake :: (HLengthEq ys n, HLengthGe xs n) => Proxy n -> HList xs -> HList ys Source #

Instances

Instances details

HTake 'HZero xs ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hTake :: Proxy 'HZero -> HList xs -> HList '[] Source #
(HLengthEq ys n, HLengthGe xs n, HTake n xs ys) => HTake ('HSucc n) (x ': xs) (x ': ys) Source #
Instance details Defined in Data.HList.HList Methods hTake :: Proxy ('HSucc n) -> HList (x ': xs) -> HList (x ': ys) Source #

drop

class HDrop (n :: HNat) xs ys | n xs -> ys where Source #

Methods

hDrop :: HLengthGe xs n => Proxy n -> HList xs -> HList ys Source #

Instances

Instances details

HDrop 'HZero xs xs Source #
Instance details Defined in Data.HList.HList Methods hDrop :: Proxy 'HZero -> HList xs -> HList xs Source #
(HLengthGe xs n, HDrop n xs ys) => HDrop ('HSucc n) (x ': xs) ys Source #
Instance details Defined in Data.HList.HList Methods hDrop :: Proxy ('HSucc n) -> HList (x ': xs) -> HList ys Source #

Conversion to and from tuples

class HTuple v t | v -> t, t -> v where Source #

Methods

hToTuple :: HList v -> t Source #

alternatively: hUncurry (,,,)

hFromTuple :: t -> HList v Source #

Instances

Instances details

HTuple ('[] :: [Type]) () Source #
Instance details Defined in Data.HList.HList Methods hToTuple :: HList '[] -> () Source # hFromTuple :: () -> HList '[] Source #
HTuple '[a, b] (a, b) Source #
Instance details Defined in Data.HList.HList Methods hToTuple :: HList '[a, b] -> (a, b) Source # hFromTuple :: (a, b) -> HList '[a, b] Source #
HTuple '[a, b, c] (a, b, c) Source #
Instance details Defined in Data.HList.HList Methods hToTuple :: HList '[a, b, c] -> (a, b, c) Source # hFromTuple :: (a, b, c) -> HList '[a, b, c] Source #
HTuple '[a, b, c, d] (a, b, c, d) Source #
Instance details Defined in Data.HList.HList Methods hToTuple :: HList '[a, b, c, d] -> (a, b, c, d) Source # hFromTuple :: (a, b, c, d) -> HList '[a, b, c, d] Source #
HTuple '[a, b, c, d, e] (a, b, c, d, e) Source #
Instance details Defined in Data.HList.HList Methods hToTuple :: HList '[a, b, c, d, e] -> (a, b, c, d, e) Source # hFromTuple :: (a, b, c, d, e) -> HList '[a, b, c, d, e] Source #
HTuple '[a, b, c, d, e, f] (a, b, c, d, e, f) Source #
Instance details Defined in Data.HList.HList Methods hToTuple :: HList '[a, b, c, d, e, f] -> (a, b, c, d, e, f) Source # hFromTuple :: (a, b, c, d, e, f) -> HList '[a, b, c, d, e, f] Source #

hTuple :: forall p f (v1 :: [Type]) a (v2 :: [Type]) t. (Profunctor p, Functor f, HTuple v1 a, HTuple v2 t) => p a (f t) -> p (HList v1) (f (HList v2)) Source #

Iso (HList v) (HList v') a b

hTuple' :: forall p f (v :: [Type]) a. (Profunctor p, Functor f, HTuple v a) => p a (f a) -> p (HList v) (f (HList v)) Source #

Iso' (HList v) a

class HTails a b | a -> b, b -> a where Source #

tails

Methods

hTails :: HList a -> HList b Source #

Instances

Instances details

HTails ('[] :: [Type]) '[HList ('[] :: [Type])] Source #
Instance details Defined in Data.HList.HList Methods hTails :: HList '[] -> HList '[HList '[]] Source #
HTails xs ys => HTails (x ': xs) (HList (x ': xs) ': ys) Source #
Instance details Defined in Data.HList.HList Methods hTails :: HList (x ': xs) -> HList (HList (x ': xs) ': ys) Source #

class HInits a b | a -> b, b -> a where Source #

inits

Methods

hInits :: HList a -> HList b Source #

Instances

Instances details

HInits1 a b => HInits a (HList ('[] :: [Type]) ': b) Source #
Instance details Defined in Data.HList.HList Methods hInits :: HList a -> HList (HList '[] ': b) Source #

class HInits1 a b | a -> b, b -> a where Source #

behaves like tail . inits

Methods

hInits1 :: HList a -> HList b Source #

Instances

Instances details

HInits1 ('[] :: [Type]) '[HList ('[] :: [Type])] Source #
Instance details Defined in Data.HList.HList Methods hInits1 :: HList '[] -> HList '[HList '[]] Source #
(HInits1 xs ys, HMapCxt HList (FHCons2 x) ys ys', HMapCons x ys ~ ys', HMapTail ys' ~ ys) => HInits1 (x ': xs) (HList '[x] ': ys') Source #
Instance details Defined in Data.HList.HList Methods hInits1 :: HList (x ': xs) -> HList (HList '[x] ': ys') Source #

data FHCons2 x Source #

similar to FHCons

Constructors

FHCons2 x

Instances

Instances details

(hxs ~ HList xs, hxxs ~ HList (x ': xs)) => ApplyAB (FHCons2 x) hxs hxxs Source #
Instance details Defined in Data.HList.HList Methods applyAB :: FHCons2 x -> hxs -> hxxs Source #

type family HMapCons (x :: *) (xxs :: [*]) :: [*] Source #

evidence to satisfy the fundeps in HInits

Instances

Instances details

type HMapCons x ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList type HMapCons x ('[] :: [Type]) = '[] :: [Type]
type HMapCons x (HList a ': b) Source #
Instance details Defined in Data.HList.HList type HMapCons x (HList a ': b) = HList (x ': a) ': HMapCons x b

type family HMapTail (xxs :: [*]) :: [*] Source #

evidence to satisfy the fundeps in HInits

Instances

Instances details

type HMapTail ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList type HMapTail ('[] :: [Type]) = '[] :: [Type]
type HMapTail (HList (a ': as) ': bs) Source #
Instance details Defined in Data.HList.HList type HMapTail (HList (a ': as) ': bs) = HList as ': HMapTail bs

partition

class HPartitionEq f x1 xs xi xo | f x1 xs -> xi xo where Source #

HPartitionEq f x1 xs xi xo is analogous to

(xi,xo) = partition (f x1) xs

where f is a "function" passed in using it's instance of HEqBy

Methods

hPartitionEq :: Proxy f -> Proxy x1 -> HList xs -> (HList xi, HList xo) Source #

Instances

Instances details

HPartitionEq (f :: k1) (x1 :: k2) ('[] :: [Type]) ('[] :: [Type]) ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hPartitionEq :: Proxy f -> Proxy x1 -> HList '[] -> (HList '[], HList '[]) Source #
(HEqBy f x1 x b, HPartitionEq1 b f x1 x xs xi xo) => HPartitionEq (f :: k) (x1 :: Type) (x ': xs) xi xo Source #
Instance details Defined in Data.HList.HList Methods hPartitionEq :: Proxy f -> Proxy x1 -> HList (x ': xs) -> (HList xi, HList xo) Source #

class HPartitionEq1 (b :: Bool) f x1 x xs xi xo | b f x1 x xs -> xi xo where Source #

Methods

hPartitionEq1 :: Proxy b -> Proxy f -> Proxy x1 -> x -> HList xs -> (HList xi, HList xo) Source #

Instances

Instances details

HPartitionEq f x1 xs xi xo => HPartitionEq1 'False (f :: k1) (x1 :: k2) x xs xi (x ': xo) Source #
Instance details Defined in Data.HList.HList Methods hPartitionEq1 :: Proxy 'False -> Proxy f -> Proxy x1 -> x -> HList xs -> (HList xi, HList (x ': xo)) Source #
HPartitionEq f x1 xs xi xo => HPartitionEq1 'True (f :: k1) (x1 :: k2) x xs (x ': xi) xo Source #
Instance details Defined in Data.HList.HList Methods hPartitionEq1 :: Proxy 'True -> Proxy f -> Proxy x1 -> x -> HList xs -> (HList (x ': xi), HList xo) Source #

groupBy

class HGroupBy (f :: t) (as :: [*]) (gs :: [*]) | f as -> gs, gs -> as where Source #

HGroupBy f x y is analogous to y = groupBy f x

given that f is used by HEqBy

Methods

hGroupBy :: Proxy f -> HList as -> HList gs Source #

Instances

Instances details

HGroupBy (f :: t) ('[] :: [Type]) ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hGroupBy :: Proxy f -> HList '[] -> HList '[] Source #
(HSpanEqBy f a as fst snd, HGroupBy f snd gs) => HGroupBy (f :: t) (a ': as) (HList (a ': fst) ': gs) Source #
Instance details Defined in Data.HList.HList Methods hGroupBy :: Proxy f -> HList (a ': as) -> HList (HList (a ': fst) ': gs) Source #

span

class HSpanEqBy (f :: t) (x :: *) (y :: [*]) (fst :: [*]) (snd :: [*]) | f x y -> fst snd, fst snd -> y where Source #

HSpanEq x y fst snd is analogous to (fst,snd) = span (== x) y

Methods

hSpanEqBy :: Proxy f -> x -> HList y -> (HList fst, HList snd) Source #

Instances

Instances details

(HSpanEqBy1 f x y fst snd, HAppendListR fst snd ~ y) => HSpanEqBy (f :: t) x y fst snd Source #
Instance details Defined in Data.HList.HList Methods hSpanEqBy :: Proxy f -> x -> HList y -> (HList fst, HList snd) Source #

class HSpanEqBy1 (f :: t) (x :: *) (y :: [*]) (i :: [*]) (o :: [*]) | f x y -> i o where Source #

Methods

hSpanEqBy1 :: Proxy f -> x -> HList y -> (HList i, HList o) Source #

Instances

Instances details

HSpanEqBy1 (f :: t) x ('[] :: [Type]) ('[] :: [Type]) ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hSpanEqBy1 :: Proxy f -> x -> HList '[] -> (HList '[], HList '[]) Source #
(HEqBy f x y b, HSpanEqBy2 b f x y ys i o) => HSpanEqBy1 (f :: t) x (y ': ys) i o Source #
Instance details Defined in Data.HList.HList Methods hSpanEqBy1 :: Proxy f -> x -> HList (y ': ys) -> (HList i, HList o) Source #

class HSpanEqBy2 (b :: Bool) (f :: t) (x :: *) (y :: *) (ys :: [*]) (i :: [*]) (o :: [*]) | b f x y ys -> i o where Source #

Methods

hSpanEqBy2 :: Proxy b -> Proxy f -> x -> y -> HList ys -> (HList i, HList o) Source #

Instances

Instances details

HSpanEqBy2 'False (f :: t) x y ys ('[] :: [Type]) (y ': ys) Source #
Instance details Defined in Data.HList.HList Methods hSpanEqBy2 :: Proxy 'False -> Proxy f -> x -> y -> HList ys -> (HList '[], HList (y ': ys)) Source #
HSpanEqBy1 f x zs i o => HSpanEqBy2 'True (f :: t) x y zs (y ': i) o Source #
Instance details Defined in Data.HList.HList Methods hSpanEqBy2 :: Proxy 'True -> Proxy f -> x -> y -> HList zs -> (HList (y ': i), HList o) Source #

zip

see alternative implementations in Data.HList.HZip

class HZipList x y l | x y -> l, l -> x y where Source #

Methods

hZipList :: HList x -> HList y -> HList l Source #

hUnzipList :: HList l -> (HList x, HList y) Source #

Instances

Instances details

HZipList ('[] :: [Type]) ('[] :: [Type]) ('[] :: [Type]) Source #
Instance details Defined in Data.HList.HList Methods hZipList :: HList '[] -> HList '[] -> HList '[] Source # hUnzipList :: HList '[] -> (HList '[], HList '[]) Source #
((x, y) ~ z, HZipList xs ys zs) => HZipList (x ': xs) (y ': ys) (z ': zs) Source #
Instance details Defined in Data.HList.HList Methods hZipList :: HList (x ': xs) -> HList (y ': ys) -> HList (z ': zs) Source # hUnzipList :: HList (z ': zs) -> (HList (x ': xs), HList (y ': ys)) Source #

Monoid instance

helper functions

data ConstMempty Source #

Constructors

ConstMempty

Instances

Instances details

(x ~ Proxy y, Monoid y) => ApplyAB ConstMempty x y Source #
Instance details Defined in Data.HList.HList Methods applyAB :: ConstMempty -> x -> y Source #

data UncurryMappend Source #

Constructors

UncurryMappend

Instances

Instances details

(aa ~ (a, a), Monoid a) => ApplyAB UncurryMappend aa a Source #
Instance details Defined in Data.HList.HList Methods applyAB :: UncurryMappend -> aa -> a Source #

data UncurrySappend Source #

Constructors

UncurrySappend

Instances

Instances details

(aa ~ (a, a), Semigroup a) => ApplyAB UncurrySappend aa a Source #
Instance details Defined in Data.HList.HList Methods applyAB :: UncurrySappend -> aa -> a Source #