Max Vasin wrote:
Bryn Keller <[EMAIL PROTECTED]> writes:
Hi folks,Hello,
[skip]
The problem is that getFieldValue returns a value of type (SqlBind a)As of HSQL 1.4 this class has method toSqlValue :: a -> String
=> 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.
which probably can help you (I really don't know).
Some RTFSing shows that in most cases toSqlValue is implemented with show.
Hi Max,
Thanks for pointing this out. It's odd that I don't see that anywhere in the docs at the HToolkit site: http://htoolkit.sourceforge.net/doc/hsql/Database.HSQL.html but GHC certainly believes it exists. However, this doesn't actually solve the problem. Substituting toSqlValue for show in printRow' gives the same compile error:
Main.hs:22:18:
Ambiguous type variable `a' in the constraint:
`SqlBind a' arising from use of `getFieldValue' at Main.hs:22:18-30
Probable fix: add a type signature that fixes these type variable(s)So, like with (show (read s)), we still can't use the function until we've established a definite type for the value, not just a type class.
Bryn
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