[Haskell-cafe] Question on "case x of g" when g is a function

[yeoh at cs.wisc.edu]

Can a kind soul please enlighten me on why f bit0 and f bit1 
both return 0?

> bit0     = False
> bit1     = True
> f x = case x of
>         bit0 -> 0
>         bit1 -> 1