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 Instances Eq RecNil Ord RecNil Read RecNil Show RecNil ReadRecRow RecNil ShowRecRow RecNil ShowLabels RecNil ToPrimExprs RecNil ExprTypes RecNil ConstantRecord RecNil RecNil ProjectRec RecNil RecNil InsertRec RecNil RecNil GetRec RecNil RecNil RecCat RecNil r r

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 Instances HasField f r => HasField f (RecCons g a r) HasField f (RecCons f a r) SetField f r a => SetField f (RecCons g b r) a SetField f (RecCons f a r) a SelectField f r a => SelectField f (RecCons g b r) a SelectField f (RecCons f a r) a (Eq a, Eq b) => Eq (RecCons f a b) (Ord a, Ord b) => Ord (RecCons f a b) (FieldTag a, Read b, ReadRecRow c) => Read (RecCons a b c) (FieldTag a, Show b, ShowRecRow c) => Show (RecCons a b c) (FieldTag a, Read b, ReadRecRow c) => ReadRecRow (RecCons a b c) (FieldTag a, Show b, ShowRecRow c) => ShowRecRow (RecCons a b c) (FieldTag f, ShowLabels r) => ShowLabels (RecCons f a r) (ExprC e, ToPrimExprs r) => ToPrimExprs (RecCons l (e a) r) (ExprType e, ExprTypes r) => ExprTypes (RecCons f e r) RecCat r1 r2 r3 => RecCat (RecCons f a r1) r2 (RecCons f a r3) (ShowConstant a, ConstantRecord r cr) => ConstantRecord (RecCons f a r) (RecCons f (Expr a) cr) (ProjectExpr e, ProjectRec r er) => ProjectRec (RecCons f (e a) r) (RecCons f (Expr a) er) (InsertExpr e, InsertRec r er) => InsertRec (RecCons f (e a) r) (RecCons f (Expr a) er) (GetValue a, GetRec er vr) => GetRec (RecCons f (Expr a) er) (RecCons f a vr)

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. Instances HasField f r => HasField f (Record r) HasField f r => HasField f (RecCons g a r) HasField f (RecCons f a 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. Instances SelectField f r a => Select (l f a) (Record r) a HasField f r => Select (Attr f a) (Rel r) (Expr a)

class SetField f r a Source

Instances SetField f r a => SetField f (Record r) a SetField f r a => SetField f (RecCons g b r) a SetField f (RecCons f a r) a

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 Instances ShowLabels RecNil ShowLabels r => ShowLabels (Record r) (FieldTag f, ShowLabels r) => ShowLabels (RecCons f a r)

class ShowRecRow r where Source

Convert a record to a list of label names and field values. Methods showRecRow :: r -> [(String, ShowS)] Source Instances ShowRecRow RecNil ShowRecRow r => ShowRecRow (Record r) (FieldTag a, Show b, ShowRecRow c) => ShowRecRow (RecCons a b c)

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. Instances ReadRecRow RecNil (FieldTag a, Read b, ReadRecRow c) => ReadRecRow (RecCons a b c)

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