-- Hoogle documentation, generated by Haddock
-- See Hoogle, http://www.haskell.org/hoogle/
-- | Template Haskell utilities for HaskellDB.
--
-- Utility functions that make defining tables, fields, and queries in
-- HaskellDB simpler.
@package haskelldb-th
@version 1.2
-- | HaskellDB is a great library for writing type-safe SQL queries. That
-- type safety comes with a significant boilerplate overhead, though.
-- This library provides utilities that help reduce that boilerplate by
-- generating the definitions, types and instances that HaskellDB expects
-- to work with. It also provides some functions for building records for
-- projections which otherwise can be quite cumbersome.
module Database.HaskellDB.CodeGen
-- | Creates a compile-time field declaration. The name given will be used
-- to create the type and the name of the field returned. It will also be
-- used to create a field nameField function which can be
-- used to place the field in a projection.
--
-- For example, mkField "fooBar" [t|Int|] produces the following
-- declarations:
--
--
-- data FooBar = FooBar
-- instance FieldTag FooBar where fieldName _ = "fooBar"
-- fooBarField :: Attr FooBar Int
-- fooBarField = mkAttr FooBar
--
--
-- mkField "Bar_Foo" [t|Bool|] would produce:
--
--
-- data Bar_Foo = Bar_Foo
-- instance FieldTag Bar_Foo where fieldName _ = "bar_Foo"
-- bar_fooField :: Attr Bar_Foo Bool
-- bar_fooField = mkAttr Bar_Foo
--
mkField :: String -> TypeQ -> Q [Dec]
-- | Creates a compile time field declaration using the given arguments for
-- the type and column name of the field. The typN argument is
-- used to produce the field nameField function which can
-- be used to add the field to a projection.
--
-- For example, mkFieldWithName "FooBar" "foo_bar" [t|Int|]
-- gives:
--
--
-- data FooBar = FooBar
-- instance FieldTag FooBar where fieldName _ = "foo_bar"
-- fooBarField :: Attr FooBar Int
-- fooBarField = mkAttr FooBar
--
--
-- Note that an error will occur if typN is not a proper
-- type/constructor name.
mkFieldWithName :: String -> String -> TypeQ -> Q [Dec]
-- | Creates a field definition in the style DBDirect uses. The
-- colName argument is used to create the data definition, type
-- synonym, and field function. The typeQ argument specifies the
-- type of the field.
--
-- For example, mkDBDirectField "fooBar" [t|Bool|] will produce:
--
--
-- data FooBar = FooBar
-- instance FieldTag FooBar where fieldName _ = "fooBar"
-- fooBar :: Attr FooBar Bool
-- fooBar = mkAttr FooBar
--
mkDBDirectField :: String -> TypeQ -> Q [Dec]
-- | Creates definitions for a table and all its fields in the style of
-- DBDirect. Takes a table name and a list of fields (as types).
-- Generates a table type and a function to construct the table. The
-- function will be the tablename in lower case. The type alias will be
-- the table name with the first character capitalized.
--
-- For example:
--
--
-- mkDBDirectTable "Table1" [("Col1", [t|Int|])
-- , ("Col2", [t|Bool|])]
--
--
-- Will produce
--
--
-- type Table1 = (RecCons Col1 (Expr Int)
-- (RecCons Col2 (Expr Bool)))
--
-- table1 :: Table Table1
-- table1 = baseTable "Table1" $
-- hdbMakeEntry Col1 #
-- hdbMakeEntry Col2
--
-- data Col1 = Col1
-- instance FieldTag Col1 where fieldName _ = "col1"
-- col1 :: Attr Col1 Int
-- col1 = mkAttr Col1
--
-- data Col2 = Col2
-- instance FieldTag Col2 where fieldName _ = "col2"
-- col2 :: Attr Col2 Int
-- col2 = mkAttr Col2
--
mkDBDirectTable :: String -> [(String, TypeQ)] -> Q [Dec]
-- | Creates definitions for a table and all its fields in the style of
-- DBDirect. Takes a table name and a list of fields (as types).
-- Generates a table type and a function to construct the table. The
-- function will be the tablename in lower case. The type alias will be
-- the table name with the first character capitalized. See
-- mkDBirectTable for an example, as that function calls this one.
mkDBDirectTableWithName :: String -> String -> [(String, TypeQ)] -> Q [Dec]
-- | Creates a type synonym for a table with the name given, using the list
-- of fields given. See mkDBDirectField for an example, as that
-- function calls this one to create the type signature.
mkDBDirectTableType :: String -> [(Name, TypeQ)] -> Q [Dec]
printQ :: (Show a) => Q a -> IO ()
class Ppr a
-- | Create a record from the list of tables and fields given. The first
-- element of each tuple is a table. The second is a list of fields from
-- that table which will be in the new record. The record will be
-- constructed in the order of tables and fields given.
--
-- This is a Template Haskell function which must be spliced in and is
-- intended to use the ' (quote) facility for capturing names.
-- An example:
--
--
-- import Status_v (Status_v, status_v)
-- import qualified Status_v as Status_v
--
-- import Dtls_v (Dtls_v, dtls_v)
-- import qualified Dtls_v as Dtls_v
--
--
-- qry = do
-- status <- table status_v;
-- dtls <- table dtls_v;
-- project $(mkRecord [('dtls, ['Dtls_v.desc
-- , 'Dtls_v.hdr_id
-- , 'Dtls_v.prt_id
-- , 'Dtls_v.dtl_id])
-- ,('status, ['Status_v.stat_nbr])])
--
--
-- The type of qry is then
--
--
-- (RecCons Dtls_v.Desc (Expr (Maybe BStr40))
-- (RecCons Dtls_v.Hdr_id (Expr (Maybe Int))
-- (RecCons Dtls_v.Prt_id (Expr (Maybe BStr30))
-- (RecCons Dtls_v.Dtl_id (Expr (Maybe Int))
-- (RecCons Status_v.Stat_nbr (Expr (Maybe Int)) RecNil))))))
--
--
-- If other fields need to be added to the record, they must come before
-- the call to mkRecord:
--
--
-- project $ filtered << someTable ! someField #
-- $(mkRecord [('dtls, ['Dtls_v.prt_desc
-- , 'Dtls.hdr_id
-- , 'Dtls.prt_id
-- , 'Dtls.dtl_id])
-- ,('status, ['Status_v.stat_nbr])])
--
mkRecord :: [(Name, [Name])] -> ExpQ