Open
Description
The lens generation example in the docs appears to be malformed. UserId seems to be used as a data constructor in the pattern match, but it is not one:
Prelude> :load Tutorial.hs
[1 of 1] Compiling Main ( Tutorial.hs, interpreted )
Tutorial.hs:39:10: error:
Not in scope: data constructor ‘UserId’
Perhaps you meant ‘User’ (line 8)
|
39 | (UserId (LensFor addressForUserId)) =
Where I have made a file called Tutorial.hs that pulls in the relevant lines from tutorials 1 and 2
Tutorial.hs
{-# LANGUAGE ImpredicativeTypes #-}
{-# LANGUAGE StandaloneDeriving #-}
import Database.Beam
import GHC.Int
import Data.Text (Text)
data UserT f
= User
{ _userEmail :: Columnar f Text
, _userFirstName :: Columnar f Text
, _userLastName :: Columnar f Text
, _userPassword :: Columnar f Text }
deriving Generic
type User = UserT Identity
type UserId = PrimaryKey UserT Identity
data AddressT f = Address
{ _addressId :: C f Int32
, _addressLine1 :: C f Text
, _addressLine2 :: C f (Maybe Text)
, _addressCity :: C f Text
, _addressState :: C f Text
, _addressZip :: C f Text
, _addressForUser :: PrimaryKey UserT f }
deriving (Generic, Beamable)
type Address = AddressT Identity
deriving instance Show (PrimaryKey UserT Identity)
deriving instance Show Address
instance Table AddressT where
data PrimaryKey AddressT f = AddressId (Columnar f Int32) deriving (Generic, Beamable)
primaryKey = AddressId . _addressId
type AddressId = PrimaryKey AddressT Identity -- For convenience
Address (LensFor addressId) (LensFor addressLine1)
(LensFor addressLine2) (LensFor addressCity)
(LensFor addressState) (LensFor addressZip)
(UserId (LensFor addressForUserId)) =
tableLenses
User (LensFor userEmail) (LensFor userFirstName)
(LensFor userLastName) (LensFor userPassword) =
tableLenses