-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/


-- | memoize functions using SQLite3 database
--   
--   memoize functions using SQLite3 database
@package memo-sqlite
@version 0.1


-- | Memoize functions in a SQLite3 database.
--   
--   The functions memoized while having type <tt>f :: k -&gt; IO v</tt>
--   must result in the same output given the same input, otherwise all
--   kinds of wrongness will result.
--   
--   The <tt>cleanup</tt> action returned by the memoizers must not be
--   called if you are going to use the memoized function again; beware.
--   
--   An example program (included in the examples directory) might look
--   like:
--   
--   <pre>
--   -- fib.hs
--   import Data.Memo.Sqlite (memoRec', readShow, table)
--   
--   import Control.Monad (liftM2)
--   import System.Environment (getArgs)
--   
--   fib :: (Integer -&gt; IO Integer) -&gt; Integer -&gt; IO Integer
--   fib _fib' n@0 = print n &gt;&gt; return 0
--   fib _fib' n@1 = print n &gt;&gt; return 1
--   fib  fib' n   = print n &gt;&gt; liftM2 (+) (fib' (n - 1)) (fib' (n - 2))
--   
--   main :: IO ()
--   main = do
--     [file, ts, ns] &lt;- getArgs
--     let Just t = table ts
--         n = read ns
--     (cleanup, fib') &lt;- memoRec' readShow file t fib
--     fib' n &gt;&gt;= \nth -&gt; putStrLn $ "fib(" ++ show n ++ ") = " ++ show nth
--     cleanup
--   </pre>
--   
--   Example usage:
--   
--   <pre>
--   ghc --make fib.hs
--   ./fib fibs.sqlite3 fibs 10
--   ./fib fibs.sqlite3 fibs 10
--   ./fib fibs.sqlite3 fibs 100
--   ./fib fibs.sqlite3 fibs 100
--   </pre>
--   
--   See also:
--   
--   <ul>
--   <li>the <tt>data-memocombinators</tt> package for pure in-memory
--   memoization.</li>
--   </ul>
module Data.Memo.Sqlite

-- | A valid SQLite3 table name.
data Table

-- | Construct a table name.
table :: String -> Maybe Table

-- | Database (de)serialization
class Sqlite t
toSqlite :: Sqlite t => t -> SQLData
fromSqlite :: Sqlite t => SQLData -> t
type Wrap s t k v = (k -> IO v) -> s k -> IO (t v)
type Unwrap s t k v = (s k -> IO (t v)) -> k -> IO v
type Wrapper s t k v = (Wrap s t k v, Unwrap s t k v)

-- | Use Read and Show for database (de)serialization.
data ReadShow t

-- | Wrapper using Read and Show for (de)serialization of both keys and
--   values.
readShow :: Wrapper ReadShow ReadShow k v
type Memo k v = (k -> IO v) -> IO (IO (), k -> IO v)
type MemoRec k v = ((k -> IO v) -> k -> IO v) -> IO (IO (), k -> IO v)
type MkMemo k v = FilePath -> Table -> Memo k v
type MkMemoRec k v = FilePath -> Table -> MemoRec k v

-- | Memoize a function using an SQLite3 database.
memo :: (Sqlite k, Sqlite v) => MkMemo k v

-- | Memoize a recursive function using an SQLite3 database.
memoRec :: (Sqlite k, Sqlite v) => MkMemoRec k v

-- | Memoize a function using an SQLite3 database, using the supplied
--   wrapper for control of (de)serialization.
memo' :: (Sqlite (s k), Sqlite (t v)) => Wrapper s t k v -> MkMemo k v

-- | Memoize a recursive function using an SQLite3 database, using the
--   supplied wrapper for control of (de)serialization.
memoRec' :: (Sqlite (s k), Sqlite (t v)) => Wrapper s t k v -> MkMemoRec k v
data SQLData :: *
SQLInteger :: Int64 -> SQLData
SQLFloat :: Double -> SQLData
SQLText :: String -> SQLData
SQLBlob :: ByteString -> SQLData
SQLNull :: SQLData
instance Eq Table
instance Ord Table
instance Show Table
instance (Read t, Show t) => Sqlite (ReadShow t)