mirror of
https://github.com/khibino/haskell-relational-record.git
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88 lines
2.9 KiB
Haskell
88 lines
2.9 KiB
Haskell
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{-# LANGUAGE FlexibleContexts #-}
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{-# LANGUAGE FlexibleInstances #-}
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{-# LANGUAGE TemplateHaskell #-}
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import Data.Int
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import Database.Record
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import Database.Relational.Query
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import Database.Relational.Query.TH
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import Person (Person (Person), person)
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import Birthday (Birthday, birthday)
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import qualified Person
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import qualified Birthday
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personAndBirthday :: Relation () (Person, Birthday)
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personAndBirthday = relation $ do
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p <- query person -- Join product accumulated
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b <- query birthday
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wheres $ p ! Person.name' .=. b ! Birthday.name'
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return $ p >< b
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personAndBirthdayL :: Relation () (Person, Maybe Birthday)
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personAndBirthdayL = relation $ do
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p <- query person
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b <- queryMaybe birthday -- Maybe not match
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wheres $ just (p ! Person.name') .=. b ?! Birthday.name'
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return $ p >< b
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personAndBirthdayO :: Relation () (Person, Birthday)
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personAndBirthdayO = relation $ do
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p <- query person
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b <- query birthday
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wheres $ p ! Person.name' .=. b ! Birthday.name'
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orderBy (b ! Birthday.day') Asc -- Specify ordering key
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orderBy (p ! Person.name') Asc
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return $ p >< b
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specifyPerson :: Relation String (Person, Birthday)
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specifyPerson = relation' $ do
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pb <- query personAndBirthday
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(ph, ()) <- placeholder (\ph' -> wheres $ pb ! fst' ! Person.name' .=. ph')
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return (ph, pb)
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data PersonAndBirthday =
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PersonAndBirthday
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{ pbPerson :: Person
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, pbBirthday :: Birthday
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}
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$(makeRelationalRecordDefault ''PersonAndBirthday)
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personAndBirthdayT :: Relation () PersonAndBirthday
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personAndBirthdayT = relation $ do
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p <- query person
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b <- query birthday
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wheres $ p ! Person.name' .=. b ! Birthday.name'
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return $ PersonAndBirthday |$| p |*| b -- Build record phantom type
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-- Birthday.day' :: Pi Birthday Day
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uncurryPB :: Pi (Person, Birthday) PersonAndBirthday
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uncurryPB = PersonAndBirthday |$| fst' |*| snd'
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personAndBirthdayP :: Relation Person PersonAndBirthday
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personAndBirthdayP = relation' $ do
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p <- query person
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b <- query birthday
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(ph, ()) <- placeholder (\ph' -> wheres $ p .=. ph')
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return $ (ph, PersonAndBirthday |$| p |*| b)
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placeholder3 :: (Monad m, PersistableWidth t, PersistableWidth t1, PersistableWidth t2, SqlProjectable p, SqlProjectable p1, SqlProjectable p2) => (p t -> p1 t1 -> p2 t2 -> m a) -> m (PlaceHolders t, (PlaceHolders t1, (PlaceHolders t2, a)))
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placeholder3 f =
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placeholder (\p0 -> placeholder (\p1 -> placeholder (\p2 -> f p0 p1 p2)))
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personAndBirthdayP2 :: Relation ((String, Int32), String) PersonAndBirthday
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personAndBirthdayP2 = relation' $ do
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p <- query person
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b <- query birthday
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(ph0, (ph1, (ph2, ()))) <-
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placeholder3 (\ph0' ph1' ph2' ->
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wheres $
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(Person |$| p ! Person.name' |*| p ! Person.age' |*| p ! Person.address')
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.=.
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(Person |$| ph0' |*| ph1' |*| ph2') )
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return $ (ph0 >< ph1 >< ph2, PersonAndBirthday |$| p |*| b)
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