Add document of alias id qualifier for table forms.

relational-join/src/Database/Relational/Query/Internal/AliasId.hs

@@ -1,10 +1,23 @@
-
+-- |
+-- Module      : Database.Relational.Query.AliasId
+-- Copyright   : 2013 Kei Hibino
+-- License     : BSD3
+--
+-- Maintainer  : ex8k.hibino@gmail.com
+-- Stability   : experimental
+-- Portability : unknown
+--
+-- This module defines qualifier for SQL table form.
+-- Contains internal structure and unsafe interfaces.
 module Database.Relational.Query.Internal.AliasId (
+  -- * Alias identifier definition
   AliasId (AliasId), primAlias, newAliasId,
 
+  -- * Qualified SQL expression
   columnN, aliasName, (<.>), columnFromId,
   asColumnN,
 
+  -- * Qualified type
   Qualified, unQualify, qualifyAlias, qualify,
 
   qualifiedSQLas
@@ -14,44 +27,59 @@ import qualified Language.SQL.Keyword as SQL
 import qualified Language.SQL.Keyword.ConcatString as SQLs
 
 
+-- | Alias id definition
 newtype AliasId = AliasId Int deriving (Show, Eq)
 
+-- | Initial value of 'AliasId'
 primAlias :: AliasId
 primAlias =  AliasId 0
 
 
+-- | New unique 'AliasId'.
 newAliasId :: AliasId -> AliasId
 newAliasId (AliasId i) = AliasId $ i + 1
 
+-- | Column name of projection index.
 columnN :: Int -> String
 columnN i = 'f' : show i
 
+-- | Alias expression string from AliasId.
 aliasName :: AliasId -> String
 aliasName (AliasId i) = 'T' : show i
 
+-- | Binary operator to qualify.
 (<.>) :: String -> String -> String
 t <.> n = t ++ '.' : n
 
+-- | Qualified expression from 'AliasId' and projection index.
 columnFromId :: AliasId -> Int -> String
 columnFromId a i = aliasName a <.> columnN i
 
+-- | Renamed column in SQL expression.
 asColumnN :: SQL.Keyword -> Int -> SQL.Keyword
 f `asColumnN` n = f `SQL.as` SQL.word (columnN  n)
 
 
--- | Qualified relaltion by alias id
-data Qualified fr =
-  Qualified
-  { unQualify    :: fr
-  , qualifyAlias :: !AliasId
-  }
+-- | Qualified query by AliasId
+data Qualified q = Qualified  q !AliasId
 
+-- | Unqualify.
+unQualify :: Qualified q -> q
+unQualify (Qualified fr _)   = fr
+
+-- | Get 'AliasId' qualifier
+qualifyAlias :: Qualified q -> AliasId
+qualifyAlias (Qualified _ i) = i
+
+-- | Add AliasId as qualifier.
 qualify :: fr -> AliasId -> Qualified fr
 qualify =  Qualified
 
+-- | 'Functor' instance of 'Qualified'
 instance Functor Qualified where
   fmap f (Qualified a i) = Qualified (f a) i
 
+-- | From 'Qualified' SQL string into 'String'.
 qualifiedSQLas :: Qualified String -> String
 qualifiedSQLas q =
   unQualify q