Typeclasses

funcpy:

Maybe => (Just value) Nothing;
a -> (Just 1);
b -> Nothing;
c v -> (? (isa v "Just") (get v "value") false);
main -> (c (Just 1));

Python:

class Type(object):
  def __init__(self, option, **values):
    self.option = option
    self.values = values
  def isa(self, option):
    return lambda: self.option == option
  def value(self, n):
    return lambda: self.values[n]
isa = lambda: lambda type: lambda: lambda option: lambda: type.isa(option)
get = lambda: lambda type: lambda: lambda value: lambda: type.value(value)

class Maybe(Type): pass
Just = lambda: lambda value: lambda: Maybe("Just", value=value)
Nothing = lambda: Maybe("Nothing")

a = lambda: Just()(lit(1))()
b = lambda: Nothing()
c = lambda: lambda b: lambda: get()(v)()("value")() if isa()(v)()("Just")() else false();