-- Basic logical operators

lnot1 : Bool -> Bool
lnot1 true  = false
lnot1 false = true

lnot2 : Bool -> Bool
lnot2 x =
  {? false if x,
     true  otherwise
  ?}

implication : Bool -> Bool -> Bool
implication x y =
  {? false   if x and not y,
     true    otherwise
  ?}

exor : Bool -> Bool -> Bool
exor x y = (x && not y) || (not x && y)