introduction_wip.md

// This is outdated and is still incomplete. Work in Progress. // I am considering starting off with an even simpler example, // of returning funds sent to a test contract.

What is GNO

Escrow model

https://paulx.dev/blog/2021/01/14/programming-on-solana-an-introduction/

package bank

// Like ERC20 but for Gno.
type Bank20 interface {
	Name() string
	Denom() string
	TotalSupply() int64
	BalanceOf(addr std.Address) int64
	Transfer(to std.Address, value int64) bool
	TransferFrom(from std.Address, to std.Address, value int64) bool
	...
	MakeOrder(from, to std.Address, amount std.Coins) Order
	
}

// NOTE: unexposed struct for security.
type order struct {
	from      Address
	to        Address
	amount    Coins
	processed bool
}

// NOTE: unexposed methods for security.
func (ch *order) string() string {
	return "TODO"
}

// Wraps the internal *order for external use.
type Order struct {
	*order
}

// XXX only exposed for demonstration. TODO unexpose, make full demo.
func NewOrder(from Address, to Address, amount Coins) Order {
	return Order{
		order: &order{
			from:   from,
			to:     to,
			amount: amount,
		},
	}
}

// Panics if error, or already processed.
func (o Order) Execute() {
	if o.order.processed {
		panic("order already processed")
	}
	o.order.processed = true
	// TODO implemement.
}

func (o Order) IsZero() bool {
	return o.order == nil
}

func (o Order) From() Address {
	return o.order.from
}

func (o Order) To() Address {
	return o.order.to
}

func (o Order) Amount() Coins {
	return o.order.amount
}

func (o Order) Processed() bool {
	return o.order.processed
}

package escrow

type EscrowTerms struct {
	PartyA  Address
	PartyB  Address
	AmountA Coins
	AmountB Coins
}

type EscrowContract struct {
	EscrowTerms
	OrderA Order
	OrderB Order
}

func CreateEscrow(terms EscrowTerms) *EscrowContract {
	return &EscrowContract{
		EscrowTerms: terms,
	}
}

func (esc *EscrowContract) SetOrderA(order Order) {
	if !esc.OrderA.IsZero() {
		panic("order-a already set")
	}
	if esc.EscrowTerms.PartyA != order.From() {
		panic("invalid order-a:from mismatch")
	}
	if esc.EscrowTerms.PartyB != order.To() {
		panic("invalid order-a:to mismatch")
	}
	if esc.EscrowTerms.AmountA != order.Amount() {
		panic("invalid order-a amount")
	}
	esc.OrderA = order
}

func (esc *EscrowContract) SetOrderB(order Order) {
	if !esc.OrderB.IsZero() {
		panic("order-b already set")
	}
	if esc.EscrowTerms.PartyB != order.From() {
		panic("invalid order-b:from mismatch")
	}
	if esc.EscrowTerms.PartyA != order.To() {
		panic("invalid order-b:to mismatch")
	}
	if esc.EscrowTerms.AmountB != order.Amount() {
		panic("invalid order-b amount")
	}
	esc.OrderA = order
}

func (esc *EscrowContract) Execute() {
	if esc.OrderA.IsZero() {
		panic("order-a not yet set")
	}
	if esc.OrderB.IsZero() {
		panic("order-b not yet set")
	}
	// NOTE: succeeds atomically.
	esc.OrderA.Execute()
	esc.OrderB.Execute()
}

Object oriented programming won market share because it provides encapsulation of logic. Gno leverages... We can provide that for smart contracts,

No persistence translation. No databases, only data structures.

How do you persist data to a store? Answer: you don't.

example with posts...

Object-level hashing.

Back to example...

Where are we?

• Gnolang
  • Version 0.1: current: persist values and run gno.lang/r/example <-- WE ARE HERE.
  • Version 0.2: 2022: persist types and nodes
• Tendermint
  • reconcile differences between pkgs/bft and mainline tendermint
  • scenario A: Tendermint/Mainline and Tendermint/GNO, two branches scenario B: Tendermint/Mainline depends on Tendermint/Gno (minimal kernel)
• SDK
  • minimal fork of cosmos-sdk to pkgs/sdk
  • part of Tendermint/GNO.

Philosophy: minimal, secure, (big-O) fast.

About the License.

pkgs/bft and pkgs/sdk to become Apache2.0. Gnolang smart contract logic not yet Apache2.0.

• Need to balance publishing, adoption, and attribution.
• Feedback wanted (in github).

Call to Action.

• Wanted: volunteers or contractors who can grok Gnolang and contribute.
  • database/language/operating-system/file-system programming required.
  • contact on telegram @cosmosjae.
• Try to make a test pass from ./tests/challenge/...
• Document differences between tendermint/gno and mainline tendermint.
• Create a plan of reconciliation between tendermint/gno and mainline tendermint.