haskell - Not in scope, whereas it is called by its full name -

a simple question:

case (hashmap.lookup "last" jsonobject) of   (just (string val)) -> data.text.io.putstrln val 

it says not in scope: data.text.io.putstrln. how be?

in haskell source files, have import modules wish use - referring symbols qualified name isn't enough.

so add

import qualified data.text.io 

to top of source file. if want refer putstrln directly, can omit qualified keyword

in particular case you'd need "hide" version prelude that, because putstrln standard library function.

import prelude hiding ( putstrln ) 

note possible refer symbols directly @ ghci prompt may have been source of confusion here.