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Add some documentaion to SqlExpr.

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This commit is contained in:
Felipe Lessa 2013-09-15 03:27:12 -03:00
parent e8013a93d4
commit 53402d726f
1 changed files with 22 additions and 3 deletions
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25
src/Database/Esqueleto/Internal/Sql.hs
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@ -232,16 +232,35 @@ type Insertion = Proxy
-- | An expression on the SQL backend. -- | An expression on the SQL backend.
data SqlExpr a where data SqlExpr a where
EInsert :: Proxy a -> (Connection -> (TLB.Builder, [PersistValue])) -> SqlExpr (Insertion a) -- | An entity, created by 'from' (cf. 'fromStart').
EEntity :: Ident -> SqlExpr (Entity val) EEntity :: Ident -> SqlExpr (Entity val)
-- | Just a tag stating that something is nullable.
EMaybe :: SqlExpr a -> SqlExpr (Maybe a) EMaybe :: SqlExpr a -> SqlExpr (Maybe a)
-- | Raw expression: states whether parenthesis are needed
-- around this expression, and takes information about the SQL
-- connection (mainly for escaping names) and returns both an
-- string ('TLB.Builder') and a list of values to be
-- interpolated by the SQL backend.
ERaw :: NeedParens -> (Connection -> (TLB.Builder, [PersistValue])) -> SqlExpr (Value a) ERaw :: NeedParens -> (Connection -> (TLB.Builder, [PersistValue])) -> SqlExpr (Value a)
EList :: SqlExpr (Value a) -> SqlExpr (ValueList a)
-- | 'EList' and 'EEmptyList' are used by list operators.
EList :: SqlExpr (Value a) -> SqlExpr (ValueList a)
EEmptyList :: SqlExpr (ValueList a) EEmptyList :: SqlExpr (ValueList a)
-- | A 'SqlExpr' accepted only by 'orderBy'.
EOrderBy :: OrderByType -> SqlExpr (Value a) -> SqlExpr OrderBy EOrderBy :: OrderByType -> SqlExpr (Value a) -> SqlExpr OrderBy
ESet :: (SqlExpr (Entity val) -> SqlExpr (Value ())) -> SqlExpr (Update val)
-- | A 'SqlExpr' accepted only by 'set'.
ESet :: (SqlExpr (Entity val) -> SqlExpr (Value ())) -> SqlExpr (Update val)
-- | An internal 'SqlExpr' used by the 'from' hack.
EPreprocessedFrom :: a -> FromClause -> SqlExpr (PreprocessedFrom a) EPreprocessedFrom :: a -> FromClause -> SqlExpr (PreprocessedFrom a)
-- | Used by 'insertSelect'.
EInsert :: Proxy a -> (Connection -> (TLB.Builder, [PersistValue])) -> SqlExpr (Insertion a)
data NeedParens = Parens | Never data NeedParens = Parens | Never
parensM :: NeedParens -> TLB.Builder -> TLB.Builder parensM :: NeedParens -> TLB.Builder -> TLB.Builder