When reading Wikipedia's entry on Haskell 2010 I stumbled across this:
-- using only prefix notation and n+k-patterns (no longer allowed in Haskell 2010)
factorial 0 = 1
factorial (n+1) = (*) (n+1) (factorial n)
What do they mean by "n+k patterns"? I guess it's the second line, but I don't get what might be wrong with it. Could anyone explain what is the issue there? Why isn't these n + k patterns more allowed in Haskell 2010?