Remove content on deriving from Generic

Author: milesfrain

language/Type-Classes.md

@@ -199,65 +199,6 @@ derive instance eqScore :: Eq Score
 derive newtype instance eqScore :: Eq Score
 ```
 
-### Deriving from `Generic`
-
-The compiler's built-in support for `Generic` unlocks convenient deriving for many other classes not listed above.
-
-For example, if we wanted to derive a `Show` instance for `MyADT` it might seem like we're out of luck: `Show` is not a class with built-in compiler support for deriving and `MyADT` is not a `newtype` (so we can't use newtype deriving).
-
-But we _can_ use `genericShow`, which works with _any_ type that has a `Generic` instance. And recall that the compiler has built-in support for deriving a `Generic` instance for any type (including the `MyADT` type). We put all those pieces together like so:
-
-```purescript
-import Data.Generic.Rep (class Generic)
-import Data.Generic.Rep.Show (genericShow)
-import Effect.Console (logShow)
-
-derive instance genericMyADT :: Generic MyADT _
-
-instance showMyADT :: Show MyADT where
-  show = genericShow
-  
-main = logShow [Some, Arbitrary 1, Contents 2.0 "Three"]
--- Prints:
--- [Some,(Arbitrary 1),(Contents 2.0 "Three")]
-```
-
-The `Show` type class is most often used for debugging data, so the output of most `Show` instances can be copy-pasted back into a PureScript source file to reconstruct the original data. The `Show` instance we created by deriving `Generic` and then using `genericShow` follows this convention.
-
-This is a good opportunity to emphasize how newtype deriving is different from instances derived by the compiler or through the `Generic` type class. In the examples below, notice how the instance derived through `Generic` includes the newtype constructor `Score`, but the newtype-derived instance simply reuses the underlying `Show` instance for `Int` and therefore does not include the constructor:
-
-```purs
-import Effect.Console (logShow)
-
-newtype Score = Score Int
-
--- newtype deriving omits wrapper with show
-derive newtype instance showScore :: Show Score
-
-main = logShow (Score 5)
--- Prints:
--- 5
-```
-
-```purs
-import Data.Generic.Rep (class Generic)
-import Data.Generic.Rep.Show (genericShow)
-import Effect.Console (logShow)
-
-newtype Score = Score Int
-
--- generic deriving prints wrapper with show
-derive instance genericScore :: Generic Score _
-instance showScore :: Show Score where
-  show = genericShow
-
-main = logShow (Score 5)
--- Prints:
--- (Score 5)
-```
-
-More information on Generic deriving is available [in the generics-rep library documentation](https://pursuit.purescript.org/packages/purescript-generics-rep). See this [blog post](https://harry.garrood.me/blog/write-your-own-generics/) for a tutorial on how to write your own `generic` functions.
-
 ## Compiler-Solvable Type Classes
 
 Some type classes can be automatically solved by the PureScript Compiler without requiring you place a PureScript statement, like `derive instance`, in your source code.