[Haskell-cafe] Re: Type classes and definite types

[Max Vasin]

Bryn Keller <xoltar at xoltar.org> writes:

> Hi folks,
Hello,
[skip]
> The problem is that getFieldValue returns a value of type (SqlBind a)
> => a. That is, there's no type information associated with this return
> value other than it's a valid  SQL value. There are no operations in
> the SqlBind class, it's just a marker as near as I can tell. 
As of HSQL 1.4 this class has method 
toSqlValue :: a -> String
which probably can help you (I really don't know).

Some RTFSing shows that in most cases toSqlValue is implemented with show.

--
WBR,
Max Vasin.