Re: [Haskelldb-users] a fix for Read (Record r)

[Bjorn B. <bri...@cs...>]

jer...@li... wrote:
> Hello,
>=20
> I am sending this via webmail, so hopefully it comes through ok :p
>=20
> The Read (Record r) instance seems to be broken. It works fine if you a=
re
> reading *just* a (Record r), but you have a data type that includes a
> (Record r), such as a list, [(Record r)], then it fails.
>=20
> I believe this is because readsReadRecRow is not returning the unused
> portion of the string. So, in the list example, the ] that closes the l=
ist
> gets thrown away, resulting in the read of the list failing.
>=20
> This version works better for me, in my 30 seconds of testing:
>=20
>=20
>>readsReadRecRow :: ReadRecRow r =3D> ReadS r
>>readsReadRecRow s =3D [(r,leftOver) | (l,leftOver) <- reads s, (r,[]) <=
-
>=20
> readRecRow l]
>=20
> Here is the test I use -- it just does a 'show' on all the rows in a
> table, and then tries to 'read' them back.
>=20
>=20
>>test =3D
>>   mysqlConnect  (MySQLOptions "host" "db" "user" "passwd" ) $ \db ->
>>	query db (table testTable) >>=3D \(r :: t) -> print (read (show r) :: =
t)
>=20
>=20
> Jeremy Shaw.

Thanks! The old version was weird, I guess noone ever tried to use it=20
for anything serious. I've pushed the patch to the main repo.


> ps. I darcs send'd the patch directly to the list, but it had
> my non-subscribed email, so it is in the moderation queue. You can
> ignore that version as the version attached to this message is the same
> thing.

This one apparantely wasn't accepted either, but I've now added both=20
your addresses to the accept list.

>  ...

/Bj=F6rn