[Haskell-cafe] Documenting strictness properties for Data.Map.Strict

[Roman Leshchinskiy]

Johan Tibell wrote:
>
>       map (\ v -> undefined)  ==  undefined
>       mapKeys (\ k -> undefined)  ==  undefined

Not really related to the question but I don't really understand how these
properties can possibly hold. Shouldn't it be:

  map (\v -> undefined) x = undefined

And even then, does this really hold for empty maps?

Roman