PopKey

PopKey gives you a static key-value storage structure backed by poppy indices. Construction is slow (multiple passes are made over the data to choose a good indexing structure), but querying should be fast, and space overhead should be much lower than Data.Map—on the data set I'm working with, Data.Map has 8.3x more overhead than PopKey—and the raw data transparently lives in an mmap'd region if you use storage, meaning the actual memory needed for usage is very low.

To construct, you will need PopKeyEncoding instances. You may choose the granularity by which you encode your data types by choosing one of two auto-deriving patterns. The first, implicitly derived via GHC Generics, will use a granular encoding, indexing fields separately internally, while the second, derived via the StoreBlob newtype, will encode the data as a single unit. Which is better depends on the situation, but as a general rule you should pack your constant-size structures into a single blob while letting your variable-sized fields use the granular encoding.

-- Encode MyType with separate indices for the [ String ] and String fields.
data MyType = MyType [ String ] String
  deriving (Generic,PopKeyEncoding)

-- Encode Point as a blob, with all 3 Int fields stored contiguously.
data Point = Point Int Int Int
  deriving (Generic,Store) -- Store here is from Data.Store
  deriving PopKeyEncoding via StoreBlob Point

Reading from and storing to disk come pre-packaged, in such a way that loading your structure from the disk will strictly load the small index metadata while leaving the large raw data to be backed by mmap. You may use this functionality as follows:

myData :: PopKeyStore Point MyType
myData = storage "myindex.poppy"

main :: IO ()
main = do
  -- your data
  let dat :: [ (Point , MyType) ] = ...

  -- store the indexed data to disk
  storePopKey myData dat

  -- load the indexed data from disk
  pk :: PopKey Point MyType <- loadPopKey myData

  ...

Poppy natively supports array-style indexing, so if your "key" set is simply the dense set of integers [ 0 .. n - 1 ] where n is the number of items in your data set, key storage may be left implicit and elided entirely. In this API, when the distinction is necessary, working with such an implicit index is signified by a trailing ', e.g., storage vs storage'.

Note that constant-factor space & time overhead is fairly high, so unless you have at least a couple thousand items, it is recommended to avoid PopKey. Once you have 10k+ items, the asymptotics should win out, and PopKey should perform well.

Documentation

data PopKey k v

Instances

Foldable (PopKey k)

Defined in PopKey.Internal3

Methods

fold :: Monoid m => PopKey k m -> m

foldMap :: Monoid m => (a -> m) -> PopKey k a -> m

foldMap' :: Monoid m => (a -> m) -> PopKey k a -> m

foldr :: (a -> b -> b) -> b -> PopKey k a -> b

foldr' :: (a -> b -> b) -> b -> PopKey k a -> b

foldl :: (b -> a -> b) -> b -> PopKey k a -> b

foldl' :: (b -> a -> b) -> b -> PopKey k a -> b

foldr1 :: (a -> a -> a) -> PopKey k a -> a

foldl1 :: (a -> a -> a) -> PopKey k a -> a

toList :: PopKey k a -> [a]

null :: PopKey k a -> Bool

length :: PopKey k a -> Int

elem :: Eq a => a -> PopKey k a -> Bool

maximum :: Ord a => PopKey k a -> a

minimum :: Ord a => PopKey k a -> a

sum :: Num a => PopKey k a -> a

product :: Num a => PopKey k a -> a

Functor (PopKey k)

Defined in PopKey.Internal3

Methods

fmap :: (a -> b) -> PopKey k a -> PopKey k b

(<$) :: a -> PopKey k b -> PopKey k a

(PopKeyEncoding k, PopKeyEncoding v) => Store (PopKey k v)

Defined in PopKey.Internal3

Methods

size :: Size (PopKey k v)

poke :: PopKey k v -> Poke ()

peek :: Peek (PopKey k v)

(!) :: PopKeyEncoding k => PopKey k v -> k -> v

Lookup by a key known to be in the structure.

lookup :: PopKeyEncoding k => PopKey k v -> k -> Maybe v

Lookup by a key which may or may not be in the structure.

makePopKey :: forall f k v. (Foldable f, PopKeyEncoding k, PopKeyEncoding v) => f (k, v) -> PopKey k v

Create a poppy-backed key-value storage structure.

makePopKey' :: forall f v. (Foldable f, PopKeyEncoding v) => f v -> PopKey Int v

Create a poppy-backed structure with elements implicitly indexed by their position.

foldrWithKey :: PopKeyEncoding k => (k -> v -> b -> b) -> b -> PopKey k v -> b

foldlWithKey' :: PopKeyEncoding k => (a -> k -> v -> a) -> a -> PopKey k v -> a

storage :: (PopKeyEncoding k, PopKeyEncoding v) => FilePath -> PopKeyStore k v

You may use storage to gain a pair of operations to serialize and read your structure from disk. This will be more efficient than if you naively serialize and store the data, as it strictly reads index metadata into memory while leaving the larger raw chunks to be backed by mmap.

storage' :: PopKeyEncoding v => FilePath -> PopKeyStore' v

Like storage, but for canonical integer keys.

newtype StoreBlob a

A simple wrapper to declare you do not want this data to be granularly partitioned by poppy.

Constructors

StoreBlob

Fields

• unStoreBlob :: a

Instances

Bounded a => Bounded (StoreBlob a)

Defined in PopKey.Encoding

Methods

minBound :: StoreBlob a

maxBound :: StoreBlob a

Enum a => Enum (StoreBlob a)

Defined in PopKey.Encoding

Methods

succ :: StoreBlob a -> StoreBlob a

pred :: StoreBlob a -> StoreBlob a

toEnum :: Int -> StoreBlob a

fromEnum :: StoreBlob a -> Int

enumFrom :: StoreBlob a -> [StoreBlob a]

enumFromThen :: StoreBlob a -> StoreBlob a -> [StoreBlob a]

enumFromTo :: StoreBlob a -> StoreBlob a -> [StoreBlob a]

enumFromThenTo :: StoreBlob a -> StoreBlob a -> StoreBlob a -> [StoreBlob a]

Generic (StoreBlob a)

Defined in PopKey.Encoding

Associated Types

type Rep (StoreBlob a) :: Type -> Type

Methods

from :: StoreBlob a -> Rep (StoreBlob a) x

to :: Rep (StoreBlob a) x -> StoreBlob a

Show a => Show (StoreBlob a)

Defined in PopKey.Encoding

Methods

showsPrec :: Int -> StoreBlob a -> ShowS

show :: StoreBlob a -> String

showList :: [StoreBlob a] -> ShowS

Eq a => Eq (StoreBlob a)

Defined in PopKey.Encoding

Methods

(==) :: StoreBlob a -> StoreBlob a -> Bool

(/=) :: StoreBlob a -> StoreBlob a -> Bool

Ord a => Ord (StoreBlob a)

Defined in PopKey.Encoding

Methods

compare :: StoreBlob a -> StoreBlob a -> Ordering

(<) :: StoreBlob a -> StoreBlob a -> Bool

(<=) :: StoreBlob a -> StoreBlob a -> Bool

(>) :: StoreBlob a -> StoreBlob a -> Bool

(>=) :: StoreBlob a -> StoreBlob a -> Bool

max :: StoreBlob a -> StoreBlob a -> StoreBlob a

min :: StoreBlob a -> StoreBlob a -> StoreBlob a

Store a => PopKeyEncoding (StoreBlob a)

Defined in PopKey.Encoding

Associated Types

type Shape (StoreBlob a)

Methods

shape :: I (Shape (StoreBlob a))

pkEncode :: StoreBlob a -> F' (Shape (StoreBlob a)) ByteString

pkDecode :: F' (Shape (StoreBlob a)) ByteString -> StoreBlob a

type Rep (StoreBlob a)

Defined in PopKey.Encoding

type Rep (StoreBlob a) = D1 ('MetaData "StoreBlob" "PopKey.Encoding" "popkey-0.1.0.2-BFihQwgzmAdCyC6xQ5QqXh" 'True) (C1 ('MetaCons "StoreBlob" 'PrefixI 'True) (S1 ('MetaSel ('Just "unStoreBlob") 'NoSourceUnpackedness 'NoSourceStrictness 'DecidedLazy) (Rec0 a)))

class PopKeyEncoding a

Inverse law: pkDecode . pkEncode = id. Note that this encoding is explicitly for use with poppy - use your discretion (or better, test!) to decide the granularity with which you wish to use this encoding as opposed to the standard store encoding. Relying more on PopKeyEncoding will probably use less space, but at the cost of storing items in less contiguous memory.

Instances

PopKeyEncoding Int16

Defined in PopKey.Encoding

Associated Types

type Shape Int16

Methods

shape :: I (Shape Int16)

pkEncode :: Int16 -> F' (Shape Int16) ByteString

pkDecode :: F' (Shape Int16) ByteString -> Int16

PopKeyEncoding Int32

Defined in PopKey.Encoding

Associated Types

type Shape Int32

Methods

shape :: I (Shape Int32)

pkEncode :: Int32 -> F' (Shape Int32) ByteString

pkDecode :: F' (Shape Int32) ByteString -> Int32

PopKeyEncoding Int64

Defined in PopKey.Encoding

Associated Types

type Shape Int64

Methods

shape :: I (Shape Int64)

pkEncode :: Int64 -> F' (Shape Int64) ByteString

pkDecode :: F' (Shape Int64) ByteString -> Int64

PopKeyEncoding Int8

Defined in PopKey.Encoding

Associated Types

type Shape Int8

Methods

shape :: I (Shape Int8)

pkEncode :: Int8 -> F' (Shape Int8) ByteString

pkDecode :: F' (Shape Int8) ByteString -> Int8

PopKeyEncoding Rational

Defined in PopKey.Encoding

Associated Types

type Shape Rational

Methods

shape :: I (Shape Rational)

pkEncode :: Rational -> F' (Shape Rational) ByteString

pkDecode :: F' (Shape Rational) ByteString -> Rational

PopKeyEncoding Word16

Defined in PopKey.Encoding

Associated Types

type Shape Word16

Methods

shape :: I (Shape Word16)

pkEncode :: Word16 -> F' (Shape Word16) ByteString

pkDecode :: F' (Shape Word16) ByteString -> Word16

PopKeyEncoding Word32

Defined in PopKey.Encoding

Associated Types

type Shape Word32

Methods

shape :: I (Shape Word32)

pkEncode :: Word32 -> F' (Shape Word32) ByteString

pkDecode :: F' (Shape Word32) ByteString -> Word32

PopKeyEncoding Word64

Defined in PopKey.Encoding

Associated Types

type Shape Word64

Methods

shape :: I (Shape Word64)

pkEncode :: Word64 -> F' (Shape Word64) ByteString

pkDecode :: F' (Shape Word64) ByteString -> Word64

PopKeyEncoding Word8

Defined in PopKey.Encoding

Associated Types

type Shape Word8

Methods

shape :: I (Shape Word8)

pkEncode :: Word8 -> F' (Shape Word8) ByteString

pkDecode :: F' (Shape Word8) ByteString -> Word8

PopKeyEncoding ByteString

Defined in PopKey.Encoding

Associated Types

type Shape ByteString

Methods

shape :: I (Shape ByteString)

pkEncode :: ByteString -> F' (Shape ByteString) ByteString

pkDecode :: F' (Shape ByteString) ByteString -> ByteString

PopKeyEncoding ByteString

Defined in PopKey.Encoding

Associated Types

type Shape ByteString

Methods

shape :: I (Shape ByteString)

pkEncode :: ByteString -> F' (Shape ByteString) ByteString0

pkDecode :: F' (Shape ByteString) ByteString0 -> ByteString

PopKeyEncoding Graph

Defined in PopKey.Encoding

Associated Types

type Shape Graph

Methods

shape :: I (Shape Graph)

pkEncode :: Graph -> F' (Shape Graph) ByteString

pkDecode :: F' (Shape Graph) ByteString -> Graph

PopKeyEncoding IntSet

Defined in PopKey.Encoding

Associated Types

type Shape IntSet

Methods

shape :: I (Shape IntSet)

pkEncode :: IntSet -> F' (Shape IntSet) ByteString

pkDecode :: F' (Shape IntSet) ByteString -> IntSet

PopKeyEncoding Text

Defined in PopKey.Encoding

Associated Types

type Shape Text

Methods

shape :: I (Shape Text)

pkEncode :: Text -> F' (Shape Text) ByteString

pkDecode :: F' (Shape Text) ByteString -> Text

PopKeyEncoding Text

Defined in PopKey.Encoding

Associated Types

type Shape Text

Methods

shape :: I (Shape Text)

pkEncode :: Text -> F' (Shape Text) ByteString

pkDecode :: F' (Shape Text) ByteString -> Text

PopKeyEncoding Integer

Defined in PopKey.Encoding

Associated Types

type Shape Integer

Methods

shape :: I (Shape Integer)

pkEncode :: Integer -> F' (Shape Integer) ByteString

pkDecode :: F' (Shape Integer) ByteString -> Integer

PopKeyEncoding Natural

Defined in PopKey.Encoding

Associated Types

type Shape Natural

Methods

shape :: I (Shape Natural)

pkEncode :: Natural -> F' (Shape Natural) ByteString

pkDecode :: F' (Shape Natural) ByteString -> Natural

PopKeyEncoding ()

Defined in PopKey.Encoding

Associated Types

type Shape ()

Methods

shape :: I (Shape ())

pkEncode :: () -> F' (Shape ()) ByteString

pkDecode :: F' (Shape ()) ByteString -> ()

PopKeyEncoding Bool

Defined in PopKey.Encoding

Associated Types

type Shape Bool

Methods

shape :: I (Shape Bool)

pkEncode :: Bool -> F' (Shape Bool) ByteString

pkDecode :: F' (Shape Bool) ByteString -> Bool

PopKeyEncoding Char

Defined in PopKey.Encoding

Associated Types

type Shape Char

Methods

shape :: I (Shape Char)

pkEncode :: Char -> F' (Shape Char) ByteString

pkDecode :: F' (Shape Char) ByteString -> Char

PopKeyEncoding Double

Defined in PopKey.Encoding

Associated Types

type Shape Double

Methods

shape :: I (Shape Double)

pkEncode :: Double -> F' (Shape Double) ByteString

pkDecode :: F' (Shape Double) ByteString -> Double

PopKeyEncoding Float

Defined in PopKey.Encoding

Associated Types

type Shape Float

Methods

shape :: I (Shape Float)

pkEncode :: Float -> F' (Shape Float) ByteString

pkDecode :: F' (Shape Float) ByteString -> Float

PopKeyEncoding Int

Defined in PopKey.Encoding

Associated Types

type Shape Int

Methods

shape :: I (Shape Int)

pkEncode :: Int -> F' (Shape Int) ByteString

pkDecode :: F' (Shape Int) ByteString -> Int

PopKeyEncoding Word

Defined in PopKey.Encoding

Associated Types

type Shape Word

Methods

shape :: I (Shape Word)

pkEncode :: Word -> F' (Shape Word) ByteString

pkDecode :: F' (Shape Word) ByteString -> Word

PopKeyEncoding a => PopKeyEncoding (Identity a)

Defined in PopKey.Encoding

Associated Types

type Shape (Identity a)

Methods

shape :: I (Shape (Identity a))

pkEncode :: Identity a -> F' (Shape (Identity a)) ByteString

pkDecode :: F' (Shape (Identity a)) ByteString -> Identity a

PopKeyEncoding a => PopKeyEncoding (First a)

Defined in PopKey.Encoding

Associated Types

type Shape (First a)

Methods

shape :: I (Shape (First a))

pkEncode :: First a -> F' (Shape (First a)) ByteString

pkDecode :: F' (Shape (First a)) ByteString -> First a

PopKeyEncoding a => PopKeyEncoding (Last a)

Defined in PopKey.Encoding

Associated Types

type Shape (Last a)

Methods

shape :: I (Shape (Last a))

pkEncode :: Last a -> F' (Shape (Last a)) ByteString

pkDecode :: F' (Shape (Last a)) ByteString -> Last a

PopKeyEncoding a => PopKeyEncoding (Max a)

Defined in PopKey.Encoding

Associated Types

type Shape (Max a)

Methods

shape :: I (Shape (Max a))

pkEncode :: Max a -> F' (Shape (Max a)) ByteString

pkDecode :: F' (Shape (Max a)) ByteString -> Max a

PopKeyEncoding a => PopKeyEncoding (Min a)

Defined in PopKey.Encoding

Associated Types

type Shape (Min a)

Methods

shape :: I (Shape (Min a))

pkEncode :: Min a -> F' (Shape (Min a)) ByteString

pkDecode :: F' (Shape (Min a)) ByteString -> Min a

PopKeyEncoding a => PopKeyEncoding (Product a)

Defined in PopKey.Encoding

Associated Types

type Shape (Product a)

Methods

shape :: I (Shape (Product a))

pkEncode :: Product a -> F' (Shape (Product a)) ByteString

pkDecode :: F' (Shape (Product a)) ByteString -> Product a

PopKeyEncoding a => PopKeyEncoding (Sum a)

Defined in PopKey.Encoding

Associated Types

type Shape (Sum a)

Methods

shape :: I (Shape (Sum a))

pkEncode :: Sum a -> F' (Shape (Sum a)) ByteString

pkDecode :: F' (Shape (Sum a)) ByteString -> Sum a

Store a => PopKeyEncoding (Ratio a)

Defined in PopKey.Encoding

Associated Types

type Shape (Ratio a)

Methods

shape :: I (Shape (Ratio a))

pkEncode :: Ratio a -> F' (Shape (Ratio a)) ByteString

pkDecode :: F' (Shape (Ratio a)) ByteString -> Ratio a

Store a => PopKeyEncoding (IntMap a)

Defined in PopKey.Encoding

Associated Types

type Shape (IntMap a)

Methods

shape :: I (Shape (IntMap a))

pkEncode :: IntMap a -> F' (Shape (IntMap a)) ByteString

pkDecode :: F' (Shape (IntMap a)) ByteString -> IntMap a

Store a => PopKeyEncoding (Seq a)

Defined in PopKey.Encoding

Associated Types

type Shape (Seq a)

Methods

shape :: I (Shape (Seq a))

pkEncode :: Seq a -> F' (Shape (Seq a)) ByteString

pkDecode :: F' (Shape (Seq a)) ByteString -> Seq a

(Ord a, Store a) => PopKeyEncoding (Set a)

Defined in PopKey.Encoding

Associated Types

type Shape (Set a)

Methods

shape :: I (Shape (Set a))

pkEncode :: Set a -> F' (Shape (Set a)) ByteString

pkDecode :: F' (Shape (Set a)) ByteString -> Set a

Store a => PopKeyEncoding (StoreBlob a)

Defined in PopKey.Encoding

Associated Types

type Shape (StoreBlob a)

Methods

shape :: I (Shape (StoreBlob a))

pkEncode :: StoreBlob a -> F' (Shape (StoreBlob a)) ByteString

pkDecode :: F' (Shape (StoreBlob a)) ByteString -> StoreBlob a

PopKeyEncoding a => PopKeyEncoding (Maybe a)

Defined in PopKey.Encoding

Associated Types

type Shape (Maybe a)

Methods

shape :: I (Shape (Maybe a))

pkEncode :: Maybe a -> F' (Shape (Maybe a)) ByteString

pkDecode :: F' (Shape (Maybe a)) ByteString -> Maybe a

Store a => PopKeyEncoding [a]

Defined in PopKey.Encoding

Associated Types

type Shape [a]

Methods

shape :: I (Shape [a])

pkEncode :: [a] -> F' (Shape [a]) ByteString

pkDecode :: F' (Shape [a]) ByteString -> [a]

(PopKeyEncoding a, PopKeyEncoding b) => PopKeyEncoding (Either a b)

Defined in PopKey.Encoding

Associated Types

type Shape (Either a b)

Methods

shape :: I (Shape (Either a b))

pkEncode :: Either a b -> F' (Shape (Either a b)) ByteString

pkDecode :: F' (Shape (Either a b)) ByteString -> Either a b

PopKeyEncoding (Proxy a)

Defined in PopKey.Encoding

Associated Types

type Shape (Proxy a)

Methods

shape :: I (Shape (Proxy a))

pkEncode :: Proxy a -> F' (Shape (Proxy a)) ByteString

pkDecode :: F' (Shape (Proxy a)) ByteString -> Proxy a

(PopKeyEncoding a, PopKeyEncoding b) => PopKeyEncoding (Arg a b)

Defined in PopKey.Encoding

Associated Types

type Shape (Arg a b)

Methods

shape :: I (Shape (Arg a b))

pkEncode :: Arg a b -> F' (Shape (Arg a b)) ByteString

pkDecode :: F' (Shape (Arg a b)) ByteString -> Arg a b

(Ord a, Store a, Store b) => PopKeyEncoding (Map a b)

Defined in PopKey.Encoding

Associated Types

type Shape (Map a b)

Methods

shape :: I (Shape (Map a b))

pkEncode :: Map a b -> F' (Shape (Map a b)) ByteString

pkDecode :: F' (Shape (Map a b)) ByteString -> Map a b

(PopKeyEncoding a, PopKeyEncoding b) => PopKeyEncoding (a, b)

Defined in PopKey.Encoding

Associated Types

type Shape (a, b)

Methods

shape :: I (Shape (a, b))

pkEncode :: (a, b) -> F' (Shape (a, b)) ByteString

pkDecode :: F' (Shape (a, b)) ByteString -> (a, b)

PopKeyEncoding a => PopKeyEncoding (Const a b)

Defined in PopKey.Encoding

Associated Types

type Shape (Const a b)

Methods

shape :: I (Shape (Const a b))

pkEncode :: Const a b -> F' (Shape (Const a b)) ByteString

pkDecode :: F' (Shape (Const a b)) ByteString -> Const a b

(PopKeyEncoding a, PopKeyEncoding b, PopKeyEncoding c) => PopKeyEncoding (a, b, c)

Defined in PopKey.Encoding

Associated Types

type Shape (a, b, c)

Methods

shape :: I (Shape (a, b, c))

pkEncode :: (a, b, c) -> F' (Shape (a, b, c)) ByteString

pkDecode :: F' (Shape (a, b, c)) ByteString -> (a, b, c)

(PopKeyEncoding a, PopKeyEncoding b, PopKeyEncoding c, PopKeyEncoding d) => PopKeyEncoding (a, b, c, d)

Defined in PopKey.Encoding

Associated Types

type Shape (a, b, c, d)

Methods

shape :: I (Shape (a, b, c, d))

pkEncode :: (a, b, c, d) -> F' (Shape (a, b, c, d)) ByteString

pkDecode :: F' (Shape (a, b, c, d)) ByteString -> (a, b, c, d)

(PopKeyEncoding a, PopKeyEncoding b, PopKeyEncoding c, PopKeyEncoding d, PopKeyEncoding e) => PopKeyEncoding (a, b, c, d, e)

Defined in PopKey.Encoding

Associated Types

type Shape (a, b, c, d, e)

Methods

shape :: I (Shape (a, b, c, d, e))

pkEncode :: (a, b, c, d, e) -> F' (Shape (a, b, c, d, e)) ByteString

pkDecode :: F' (Shape (a, b, c, d, e)) ByteString -> (a, b, c, d, e)

data PopKeyStore k v

Instances

StorePopKey k v (PopKeyStore k v)

Defined in PopKey.Internal3

Associated Types

type Input (PopKeyStore k v)

Methods

storePopKey :: Foldable t => PopKeyStore k v -> t (Input (PopKeyStore k v)) -> IO ()

loadPopKey :: PopKeyStore k v -> IO (PopKey k v)

type Input (PopKeyStore k v)

Defined in PopKey.Internal3

type Input (PopKeyStore k v) = (k, v)

data PopKeyStore' v

Instances

StorePopKey Int v (PopKeyStore' v)

Defined in PopKey.Internal3

Associated Types

type Input (PopKeyStore' v)

Methods

storePopKey :: Foldable t => PopKeyStore' v -> t (Input (PopKeyStore' v)) -> IO ()

loadPopKey :: PopKeyStore' v -> IO (PopKey Int v)

type Input (PopKeyStore' v)

Defined in PopKey.Internal3

type Input (PopKeyStore' v) = v

class StorePopKey k v f | f -> k, f -> v where

Associated Types

type Input f

Methods

storePopKey :: Foldable t => f -> t (Input f) -> IO ()

loadPopKey :: f -> IO (PopKey k v)

Instances

StorePopKey Int v (PopKeyStore' v)

Defined in PopKey.Internal3

Associated Types

type Input (PopKeyStore' v)

Methods

storePopKey :: Foldable t => PopKeyStore' v -> t (Input (PopKeyStore' v)) -> IO ()

loadPopKey :: PopKeyStore' v -> IO (PopKey Int v)

StorePopKey k v (PopKeyStore k v)

Defined in PopKey.Internal3

Associated Types

type Input (PopKeyStore k v)

Methods

storePopKey :: Foldable t => PopKeyStore k v -> t (Input (PopKeyStore k v)) -> IO ()

loadPopKey :: PopKeyStore k v -> IO (PopKey k v)