units2.purs.hs

data Zero = Zero
 
data Succ a = Succ a
 
pred = \s -> case s of Succ a -> a
 
meters = \n -> 
  { multiply: \v -> v { value = n * v.value, meters = Succ (v.meters) }
  , divide: \v -> v { value = n / v.value, meters = pred (v.meters) }      
  }      
 
seconds = \n -> 
  { multiply: \v -> v { value = n * v.value, seconds = Succ (v.seconds) }
  , divide: \v -> v { value = n / v.value, seconds = pred (v.seconds) }      
  }    
 
(*.) = \n m -> 
  { multiply: \x -> m.multiply (n.multiply x)
  , divide: \x -> m.divide (n.divide x) 
  }
 
(+.) = \f g -> 
  { multiply: \x -> 
    { var v1 = f.multiply x;
      var v2 = g.multiply x;
      return v2 { value = v1.value + v2.value }; }
  , divide: \x -> 
    { var v1 = f.divide x;
      var v2 = g.divide x;
      return v2 { value = v1.value + v2.value }; }
  }
  
(~) = \f g -> 
  { multiply: \x -> 
    { var v1 = f.multiply x;
      var v2 = g.multiply x;
      return v2 { value = v1.value - v2.value }; }
  , divide: \x ->
    { var v1 = f.divide x;
      var v2 = g.divide x;
      return v2 { value = v1.value - v2.value }; }
  }
 
(/.) = \n m -> 
  { multiply: \x -> m.divide (n.multiply x)
  , divide: \x -> m.multiply (n.divide x) 
  }
 
test = seconds 1 /. seconds 1