How to assign to mvar with case syntax?

Question

I'am asking if i can add same think like that :

if maVar == "false" then maVar = "" else maVar = maVar

in tmy code haskell (yesod)

let maVar= unpack $ case Map.lookup "maVarSession" sess of
        Just a -> a
        Nothing -> "Nothing"

Answer 1

No, maVar is imutable and it is String always.

In Haskell there aren't any false. It has False.

You could do next:

let maVar = ...
in
  let maVarNew = if maVar == "Nothing" then "" else maVar
  in