[Haskelldb-users] Template haskell and haskelldb

[Justin B. <jgb...@gm...>]

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