code/morley-prelude/CHANGES.md

 <!-- Unreleased: append new entries here -->
 
+* [!1080](https://gitlab.com/morley-framework/morley/-/merge_requests/1080)
+  Add more `PrettyShow` type instances
+  + For lists
+  + Add instances that forbid defining `PrettyShow` for `String`, `Text`, and `ByteString`
 * [!1075](https://gitlab.com/morley-framework/morley/-/merge_requests/1075)
   Add suitable types for oddly-sized unsigned integers
   + Add a dependency on `OddWord`.

code/morley-prelude/src/Morley/Prelude/Show.hs

@@ -17,6 +17,7 @@ import Data.Fixed (Fixed)
 import Data.Time (NominalDiffTime)
 import Data.Typeable (TypeRep)
 import Data.Word.Odd (Word62, Word63)
+import GHC.TypeLits (ErrorMessage(..), TypeError)
 import Language.Haskell.Extension (KnownExtension)
 import Language.Haskell.TH (Name)
 import Language.Haskell.TH.PprLib (Doc)
@@ -70,6 +71,37 @@ type instance PrettyShow TypeRep = ()
 -- NominalDiffTime show instance is human-readable instead of machine-readable
 type instance PrettyShow NominalDiffTime = ()
 
+-- Lists are human-readable if each element in it is
+type instance PrettyShow [a] = PrettyShow a
+
+-- Show instances for String and similar types are not entirely human-readable.
+-- For instance:
+--
+-- >>> print "A string with \"quotes\""
+-- "A string with \"quotes\""
+--
+-- >>> print "A string with non-ascii characters हि"
+-- "A string with non-ascii characters \2361\2367"
+type instance PrettyShow Text = TypeError (
+  'Text "Show instance for Text is not pretty" ':$$:
+  'Text "Consider relying on the Buildable instance"
+  )
+type instance PrettyShow LText = TypeError (
+  'Text "Show instance for lazy Text is not pretty" ':$$:
+  'Text "Consider relying on the Buildable instance"
+  )
+type instance PrettyShow Char = TypeError (
+  'Text "Show instance for String and Char is not pretty" ':$$:
+  'Text "Consider relying on the Buildable instance"
+  )
+
+type instance PrettyShow ByteString = TypeError (
+  'Text "Show instance for ByteString is not pretty"
+  )
+type instance PrettyShow LByteString = TypeError (
+  'Text "Show instance for lazy ByteString is not pretty"
+  )
+
 -- | A version of 'Universum.show' that requires the value to have a human-readable
 -- 'Show' instance.
 show :: forall b a. (PrettyShow a, Show a, IsString b) => a -> b