SML like simple datatype in python

• usage

  from util import dt
  mdt = dt.Datatype()
  mcs = dt.Constructor()
  mdt.Nat('int') == mcs.Zero() \
                  |  mcs.Succ('nat')
  Nat = mdt.Nat
  Zero = mcs.Zero
  Succ = mcs.Succ
  zero = Zero()
  print( zero ) # => Zero
  print( Succ(zero) ) # => Succ [Zero, '...']
      

Simple Pattern Match in python

• usage

  from util import dt
  mdt = dt.Datatype()
  mcs = dt.Constructor()
  mdt.Nat('int') == mcs.Zero() \
                  |  mcs.Succ('nat')
  Nat = mdt.Nat
  Zero = mcs.Zero
  Succ = mcs.Succ
  zero = Zero()
  print( zero ) # => Zero
  print( Succ(zero) ) # => Succ [Zero, '...']
  from util.Match import *
  @matcher(Zero,False) # Zero is class ,False is tail recursion switch 
  def toInt(self):
      return 0
  @matcher(Succ,False)
  def toInt(self):
      # self.nat is before mcs.Succ('nat') 
      return 1 + self.nat.toInt()
  one = Succ(zero)
  two = Succ(one)
  print( toInt(zero) ,toInt(two) ) # => 0 ,2
      

Simple tail recursion

• usage

  # todo,you can see List.py 
      

List usage see example_list.py