Database.HaskellDB.HDBRec

This is a replacement for some of TREX.

Record types

data RecNil

The empty record.

Constructors

RecNil

Instances

Eq RecNil

Ord RecNil

Read RecNil

Show RecNil

ReadRecRow RecNil

ShowRecRow RecNil

ShowLabels RecNil

ToPrimExprs RecNil

RelToRec RecNil

ExprTypes RecNil

ConstantRecord RecNil RecNil

ProjectRec RecNil RecNil

InsertRec RecNil RecNil

GetRec RecNil RecNil

RecCat RecNil r r

data RecCons f a b

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)

(RelToRec rest, FieldTag f) => RelToRec (RecCons f (Expr a) rest)

(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

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

The empty record

(.=.)

Arguments

:: l f a

Label

-> a

Value

-> Record (RecCons f a RecNil)

New record

Creates one-field record from a label and a value

(#)

Arguments

:: Record (RecCons f a RecNil)

Field to add

-> (b -> c)

Rest of record

-> b -> RecCons f a c

New record

Adds the field from a one-field record to another record.

Labels

class FieldTag f where

Class for field labels.

Methods

fieldName :: f -> String

Gets the name of the label.

Record predicates and operations

class HasField f r

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

Methods

(!) :: r -> f -> a

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)

Field selection operator. It is overloaded to work for both relations in a query and the result of a query. That is, it corresponds to both ! and !. from the original HaskellDB. An overloaded operator was selected because users (and the developers) always forgot to use !. instead of ! on query results.

class SetField f r a

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

class RecCat r1 r2 r3 | r1 r2 -> r3 where

Methods

recCat :: r1 -> r2 -> r3

Concatenates two records.

Instances

RecCat RecNil r r

RecCat r1 r2 r3 => RecCat (Record r1) (Record r2) (Record r3)

RecCat r1 r2 r3 => RecCat (RecCons f a r1) r2 (RecCons f a r3)

Showing and reading records

class ShowLabels r where

Methods

recordLabels :: r -> [String]

Instances

ShowLabels RecNil

ShowLabels r => ShowLabels (Record r)

(FieldTag f, ShowLabels r) => ShowLabels (RecCons f a r)

class ShowRecRow r where

Convert a record to a list of label names and field values.

Methods

showRecRow :: r -> [(String, ShowS)]

Instances

ShowRecRow RecNil

ShowRecRow r => ShowRecRow (Record r)

(FieldTag a, Show b, ShowRecRow c) => ShowRecRow (RecCons a b c)

class ReadRecRow r where

Methods

readRecRow :: [(String, String)] -> [(r, [(String, String)])]

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)