haskelldb-0.12: SQL unwrapper for Haskell. Source code Contents Index

Database.HaskellDB.HDBRec Portability non-portable Stability experimental Maintainer haskelldb-users@lists.sourceforge.net

Contents Record types Record construction Labels Record predicates and operations Showing and reading records

Description

This is a replacement for some of TREX.

Synopsis

data RecNil = RecNil data RecCons f a b = RecCons a b type Record r = RecNil -> r emptyRecord :: Record RecNil (.=.) :: l f a -> a -> Record (RecCons f a RecNil) (#) :: Record (RecCons f a RecNil) -> (b -> c) -> b -> RecCons f a c class FieldTag f where fieldName :: f -> String class HasField f r class Select f r a | f r -> a where (!) :: r -> f -> a class SetField f r a setField :: SetField f r a => l f a -> a -> r -> r class ShowLabels r where recordLabels :: r -> [String] class ShowRecRow r where showRecRow :: r -> [(String, ShowS)] class ReadRecRow r where readRecRow :: [(String, String)] -> [(r, [(String, String)])]

Record types

data RecNil Source

The empty record. Constructors RecNil

data RecCons f a b Source

Constructor that adds a field to a record. f is the field tag, a is the field value and b is the rest of the record. Constructors RecCons a b

type Record r = RecNil -> r Source

The type used for records. This is a function that takes a RecNil so that the user does not have to put a RecNil at the end of every record.

Record construction

emptyRecord :: Record RecNil Source

The empty record

(.=.) Source

:: => l f a Value -> a New record -> Record (RecCons f a RecNil) Creates one-field record from a label and a value

(#) Source

:: => Record (RecCons f a RecNil) Rest of record -> b -> c New record -> b -> RecCons f a c Adds the field from a one-field record to another record.

Labels

class FieldTag f where Source

Class for field labels. Methods fieldName :: f -> String Source Gets the name of the label.

Record predicates and operations

class HasField f r Source

The record r has the field f if there is an instance of HasField f r.

class Select f r a | f r -> a where Source

Methods (!) :: r -> f -> a Source Field selection operator. It is overloaded so that users (read HaskellDB) can redefine it for things with phantom record types.

class SetField f r a Source

setField :: SetField f r a => l f a -> a -> r -> r Source

Showing and reading records

class ShowLabels r where Source

Methods recordLabels :: r -> [String] Source

class ShowRecRow r where Source

Convert a record to a list of label names and field values. Methods showRecRow :: r -> [(String, ShowS)] Source

class ReadRecRow r where Source

Methods readRecRow :: [(String, String)] -> [(r, [(String, String)])] Source Convert a list of labels and strins representating values to a record.

Produced by Haddock version 2.6.0