Database.Record.Persistable

This module defines interfaces between Haskell type and list of SQL type.

Specify SQL type

data PersistableSqlType q

Proof object to specify type q is SQL type

runPersistableNullValue :: PersistableSqlType q -> q

Null value of SQL type q.

unsafePersistableSqlTypeFromNull

Arguments

:: q

SQL null value of SQL type q

-> PersistableSqlType q

Result proof object

Unsafely generate PersistableSqlType proof object from specified SQL null value which type is q.

Specify record width

data PersistableRecordWidth a

Proof object to specify width of Haskell type a when converting to SQL type list.

runPersistableRecordWidth :: PersistableRecordWidth a -> Int

Get width Int value of record type a.

unsafePersistableRecordWidth

Arguments

:: Int

Specify width of Haskell type a

-> PersistableRecordWidth a

Result proof object

Unsafely generate PersistableRecordWidth proof object from specified width of Haskell type a.

unsafeValueWidth :: PersistableRecordWidth a

Unsafely generate PersistableRecordWidth proof object for Haskell type a which is single column type.

(<&>) :: PersistableRecordWidth a -> PersistableRecordWidth b -> PersistableRecordWidth (a, b)

Derivation rule of PersistableRecordWidth for tuple (,) type.

maybeWidth :: PersistableRecordWidth a -> PersistableRecordWidth (Maybe a)

Derivation rule of PersistableRecordWidth from from Haskell type a into for Haskell type Maybe a.

Bidirectional conversion between single column type and SQL type

data PersistableSqlValue q a

Proof object to specify value type a is convertible with SQL type q

persistableSqlValue :: PersistableSqlType q -> (q -> a) -> (a -> q) -> PersistableSqlValue q a

Axiom of PersistableSqlValue for SQL type q and Haskell type a.

toValue

Arguments

:: PersistableSqlValue q a

Proof object which has capability to convert

-> q

SQL type

-> a

Haskell type

Run PersistableSqlValue proof object. Convert from SQL type q into Haskell type a.

fromValue

Arguments

:: PersistableSqlValue q a

Proof object which has capability to convert

-> a

Haskell type

-> q

SQL type

Run PersistableSqlValue proof object. Convert from Haskell type a into SQL type q.

Inference rules for proof objects

class Eq q => PersistableType q where

Interface of inference rule for PersistableSqlType proof object

Methods

persistableType :: PersistableSqlType q

sqlNullValue :: PersistableType q => q

Inferred Null value of SQL type.

class PersistableType q => PersistableValue q a where

Interface of inference rule for PersistableSqlValue proof object

Methods

persistableValue :: PersistableSqlValue q a

Infer PersistableSqlValue proof object.

fromSql :: PersistableValue q a => q -> a

Run inferred PersistableSqlValue proof object. Convert from SQL type q into Haskell type a.

toSql :: PersistableValue q a => a -> q

Run inferred PersistableSqlValue proof object. Convert from Haskell type a into SQL type q.

class PersistableWidth a where

Interface of inference rule for PersistableRecordWidth proof object

Methods

persistableWidth :: PersistableRecordWidth a

Instances

PersistableWidth Bool

PersistableWidth Char

PersistableWidth Int

PersistableWidth Int16

PersistableWidth Int32

PersistableWidth Int64

PersistableWidth String

PersistableWidth ()

Inference rule of PersistableRecordWidth for Haskell unit () type. Derive from axiom.

PersistableWidth a => PersistableWidth (Maybe a)

Inference rule of PersistableRecordWidth proof object for Maybe type.

(PersistableWidth a, PersistableWidth b) => PersistableWidth (a, b)

Inference rule of PersistableRecordWidth proof object for tuple (a, b) type.

derivedWidth :: PersistableWidth a => (PersistableRecordWidth a, Int)

Pass type parameter and inferred width value.