I know this is code is a bit silly, but can someone explain why this isList [42] returns True whereas isList2 [42] prints False, and how to prevent this? I'd like to get better understanding of some of the more obscure GHC type extensions, and I thought this would be an interesting example to figure out.

{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE OverlappingInstances #-}
{-# LANGUAGE IncoherentInstances #-}

class IsList a where
  isList :: a -> Bool

instance IsList a where
  isList x = False

instance IsList [a] where
  isList x = True

isList2 = isList

main = 
  print (isList 42) >> 
  print (isList2 42) >> 
  print (isList [42]) >> 
  print (isList2 [42])
haskell types
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