Re: [Haskelldb-users] Template haskell and haskelldb

[Bjorn B. <bj...@br...>]

On Fri, Apr 4, 2008 at 10:20 PM, Justin Bailey <jgb...@gm...> wrote:
> I just spent most of the day creating some TH functions that generate
>  DirectDB style table and field definitions. It allows me to create a
>  module that exports a table like so:
>
>  module My_Table where
>
>  $(mkDBDirectTable "my_table"
>   [("event_dtl_id", [t|Int|])
>   , ("event_hdr_id", [t|Int|])
>   , ("foo", [t|Int|])
>   , ("bar", [t|Int|])])
>
>  The above is a table name and a list of fields with types. TH
>  generates appropriate haskell source so the definition looks just
>  something DBDirect would produce:
>
>  module My_Table where
>
>  type My_table =
>     (RecCons Pts_dlvry_carrier_flight_id (Expr Int)
>      (RecCons Pts_dlvry_carrier_id (Expr Int) ...))
>
>  my_table :: Table My_table
>  my_table = baseTable "my_table" $
>                            hdbMakeEntry Event_dtl_id # ...
>
>  data Event_dtl_id = Event_dtl_id
>
>  instance FieldTag Event_dtl_id where
>     fieldName _ = "event_dtl_id"
>
>  event_dtl_id :: Attr Event_dtl_id
>  event_dtl_id = mkAttr Event_dtl_id
>  ....
>
>  I also have a function that creates a field using TH, which is very
>  useful when you need "fake" fields in a projection:
>
>   $(mkDBDirectField "filtered" [t|Bool|])
>
>  which produces something like:
>
>  data Filtered = Filtered
>
>  instance FieldTag Filtered where
>     fieldName _ = "filtered"
>
>  filtered :: Attr Filtered
>  filtered = mkAttr Filtered
>
>  Is there a place in the haskelldb source for TH utilities like this?
>
>  Justin

Nice! I seem to recall there being such code somewhere in the past,
but I have no idea where.

I should probably go in a separate cabal package, since it adds a dep
on TH. Maybe add a haskelldb-th dir in the repo and put the code +
.cabal there.

I should move the repo to code.haskell.org to remove me as a
bottleneck for your work.

/Bjorn