ethereum training

Smart Contracts Overview

ethereum POC5 (well, almost...)

ethercasts

Prerequisites

• How bitcoin works under the hood (22m)
• Ethereum introduction by Vitalik Buterin (28m)
• Introduction to smart contracts (16m)
• Basic Python, JavaScript or PHP (~10h)
  http://www.codecademy.com/tracks/python

Training Modules

• Smart Contracts Overview
  Use Cases, Platform, Clients, Languages, Resources
• Ethereum Virtual Machine
  Accounts, Transactions, Fees, Execution & Operations
• Serpent
  Python like programming language
• Interfaces
  JSONRPC, JavaScript client bindings

What can you do with smart contracts?

• Create a Currency
• Financial Derivatives
• Savings Wallet
• Data storage
• Name Registration
• Decentralized Organizations

Ethereum Platform

• Contracts live on the Ethereum block chain
• Have own Ethereum address and balance
• Can send and receive transactions
• "Activated" when you send a transaction to it

• Turing complete language (~85 opcodes)
• Executed & verified by all miners
• Fee per CPU step (extra for storage, tx, crypto)
• 2^256 Storage entries
• Contracts can call (and create!) other contracts

Clients

AlethZero

Ethereal

And more..

• pyethereum - Python
• ethereumj - pure Java
• ethereumjs-lib - JavaScript
• node-ethereum - NodeJS / JavaScript

Languages

EtherScript

TXVALUE PUSH 25 PUSH 10 PUSH 18 EXP MUL LE NOT PUSH 34 JMPI STOP PUSH 34
JMP PUSH 0 TXDATA SLOAD NOT PUSH 0 TXDATA PUSH 1000 LT NOT MUL NOT NOT
PUSH 34 JMPI STOP PUSH 1 TXDATA PUSH 0 TXDATA SSTORE

Serpent: Python Like Language

init:
    contract.storage[msg.sender] = 1000000
code:
    if msg.datasize == 1:
        addr = msg.data[0]
        return(contract.storage[addr])
    else:
        from = msg.sender
        fromvalue = contract.storage[from]
        to = msg.data[0]
        value = msg.data[1]
        if fromvalue >= value:
            contract.storage[from] = fromvalue - value
            contract.storage[to] = contract.storage[to] + value
            return(1)
        else:
            return(0)

LLL: Lisp-Like Language

{
  [0] "Splitter"
  (call (- (gas) 100) 0x2d0aceee7e5ab874e22ccf8d1a649f59106d74e8 0 0 8 0 0)

  (return 0 (lll {
    [count] (/ (calldatasize) 32)
    [pay] (/ (callvalue) @count)

    ;; Cycle through each address
    (for {} (< @i @count) [i](+ @i 1)
      ;; Send to 'i'th argument (assuming it's an address).
      (call (- (gas) 100) (calldataload (* @i 32)) @pay 0 0 0 0)
    )
  } 0))
}

Mutan: Go-Like Language

int32 a = 20
int32 b = 10

var str = "hello"
otherStr := "world"

if a < b {
    exit()
} else {
    // :-)
    if !a {
        if this.data[0] ** 10 >= 10 {
            this.data[0] = 1000;
        }
    }
}

Online Tools

EtherScripter.com

MintChalk.com

mutan.jeffew.com

Online Resources

• Ethereum Whitepaper
• Ethereum Yellowpaper
• Writing Smart Contracts FAQ
• Ethereum Wiki
• EtherCasts.com Presentations & Screencasts

What's next?

⇒ Ethereum Virtual Machine

Questions / Feedback?