Replace individual list elements in Haskell?

Question

I have a list of elements and I wish to update them:

from this: [\"Off\",\"Off\",\"Off\",\"Off\"]

to this: [\"Off\",\"Off\",\"On\",\"Off\

Answer 1

I think you should consider using a data structure other than List. For example, if you just want to have a state of four on/off switches then:

data State = St { sw1, sw2, sw3, sw4 :: Bool }

For a dynamic number of switches then consider a mapping from switch name to Bool.