GHC 8.0 and later come with the `DeriveLift` extension for deriving
instances of `Language.Haskell.TH.Syntax.Lift`. `yesod-core` supports
GHC 8.2 and up, so it is able to make use of this. Not only does
`DeriveLift` make for much shorter code, but it also fixes warnings
that you get when compiling `yesod-core` with GHC 8.10 or later:
```
[20 of 31] Compiling Yesod.Routes.TH.Types ( src/Yesod/Routes/TH/Types.hs, interpreted )
src/Yesod/Routes/TH/Types.hs:34:10: warning: [-Wmissing-methods]
• No explicit implementation for
‘liftTyped’
• In the instance declaration for ‘Lift (ResourceTree t)’
|
34 | instance Lift t => Lift (ResourceTree t) where
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
src/Yesod/Routes/TH/Types.hs:49:10: warning: [-Wmissing-methods]
• No explicit implementation for
‘liftTyped’
• In the instance declaration for ‘Lift (Resource t)’
|
49 | instance Lift t => Lift (Resource t) where
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
src/Yesod/Routes/TH/Types.hs:59:10: warning: [-Wmissing-methods]
• No explicit implementation for
‘liftTyped’
• In the instance declaration for ‘Lift (Piece t)’
|
59 | instance Lift t => Lift (Piece t) where
| ^^^^^^^^^^^^^^^^^^^^^^^^
src/Yesod/Routes/TH/Types.hs:78:10: warning: [-Wmissing-methods]
• No explicit implementation for
‘liftTyped’
• In the instance declaration for ‘Lift (Dispatch t)’
|
78 | instance Lift t => Lift (Dispatch t) where
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^
```
This is because `DeriveLift` fills in implementations of `liftTyped`,
a method that was introduced to `Lift` in `template-haskell-2.16.0.0`
(bundled with GHC 8.10).
