add two examples

docs/examples.rst

@@ -1,2 +1,89 @@
+.. _examples:
+
 PyTeal Examples
 ===============
+
+We showcase some example PyTeal programs:
+
+
+Split Payment
+~~~~~~~~~~~~~
+
+*Split Payment* splits payment between :code:`tmpl_rcv1` and
+:code:`tmpl_rcv2` on the ratio of :code:`tmpl_ratn / tmpl_ratd` ::
+
+	from pyteal import *
+
+	"""Split
+	"""
+
+	# template variables
+	tmpl_fee = Int(1000)
+	tmpl_rcv1 = Addr("6ZHGHH5Z5CTPCF5WCESXMGRSVK7QJETR63M3NY5FJCUYDHO57VTCMJOBGY")
+	tmpl_rcv2 = Addr("7Z5PWO2C6LFNQFGHWKSK5H47IQP5OJW2M3HA2QPXTY3WTNP5NU2MHBW27M")
+	tmpl_own = Addr("5MK5NGBRT5RL6IGUSYDIX5P7TNNZKRVXKT6FGVI6UVK6IZAWTYQGE4RZIQ")
+	tmpl_ratn  = Int(1)
+	tmpl_ratd = Int(3)
+	tmpl_min_pay = Int(1000)
+	tmpl_timeout = Int(3000)
+	
+	split_core = (Txn.type_enum() == Int(1)).And(Txn.fee() < tmpl_fee)
+
+	split_transfer = And(Gtxn.sender(0) == Gtxn.sender(1),
+                             Txn.close_remainder_to() == Global.zero_address(),
+                             Gtxn.receiver(0) == tmpl_rcv1,
+                             Gtxn.receiver(1) == tmpl_rcv2,
+                             Gtxn.amount(0) == ((Gtxn.amount(0) + Gtxn.amount(1)) * tmpl_ratn) / tmpl_ratd,
+                             Gtxn.amount(0) == tmpl_min_pay)
+
+	split_close = And(Txn.close_remainder_to() == tmpl_own,
+                          Txn.receiver() == Global.zero_address(),
+                          Txn.first_valid() == tmpl_timeout)
+
+	split = And(split_core,
+                    If(Global.group_size() == Int(2),
+                       split_transfer,
+                       split_close))
+
+	print(split.teal())
+
+
+Periodic Payment
+~~~~~~~~~~~~~~~~
+
+*Periodic Payment*  allows some account to execute periodic withdrawal of funds. This PyTeal program creates an contract account that allows :code:`tmpl_rcv` to withdraw TMPL_AMT every :code:`tmpl_period` rounds for :code:`tmpl_dur` after every multiple
+of :code:`tmpl_period`.
+
+After :code:`tmpl_timeout`, all remaining funds in the escrow
+are available to :code:`tmpl_rcv` ::
+
+  from pyteal import *
+
+  tmpl_fee = Int(1000)
+  tmpl_period = Int(50)
+  tmpl_dur = Int(5000)
+  tmpl_x = Bytes("base64", "023sdDE2")
+  tmpl_amt = Int(2000)
+  tmpl_rcv = Addr("6ZHGHH5Z5CTPCF5WCESXMGRSVK7QJETR63M3NY5FJCUYDHO57VTCMJOBGY")
+  tmpl_timeout = Int(30000)
+
+  periodic_pay_core = And(Txn.type_enum() == Int(1),
+                         Txn.fee() < tmpl_fee,
+                         Txn.first_valid() % tmpl_period == Int(0),
+                         Txn.last_valid() == tmpl_dur + Txn.first_valid(),
+                         Txn.lease() == tmpl_x)
+                      
+
+  periodic_pay_transfer = And(Txn.close_remainder_to() ==  Global.zero_address(),
+                              Txn.receiver() == tmpl_rcv,
+                              Txn.amount() == tmpl_amt)
+
+  periodic_pay_close = And(Txn.close_remainder_to() == tmpl_rcv,
+                           Txn.receiver() == Global.zero_address(),
+                           Txn.first_valid() == tmpl_timeout,
+                           Txn.amount() == Int(0))
+
+  periodic_pay_escrow = periodic_pay_core.And(periodic_pay_transfer.Or(periodic_pay_close))
+
+  print(periodic_pay_escrow.teal())
+