Concepts to Cover

• Contract

• Resource (Composite Type)

• Event

• Interface

  • Restricted types

• Functions

  • Function Preconditions and Postconditions

• Optionals

• References

• Capabilities

• Access Control

• Script

• Transactions

Types to Cover

• UInt64
• UFix64
• Address
• AuthAccount
• Array
• Dictionary

Schedule

Day 1

• Types
• Functions
• Contract
• Transaction
• Script

Day 2

• Resource (Composite Type)
• Interface
  • Restricted types
• Optionals
• References
• Capabilities

Day 3

• Flow CLI
• Flow Emulator

Day 4

• Transaction Lifecycle
• Event
• Function Preconditions and Postconditions
• Access Control

Day 5

• Testnet

Flow CLI

flow emulator start

flow keys generate --sig-algo "ECDSA_secp256k1"

flow accounts create \
  --key "2824549ffffe11edc1e170f0c1186b9a588444812cdfe9ec0c93df8b858679c0afb4f006a7c273c0fdd18f62e3632fb3f984a682a928fe3c2c82d845a1245137" \
  --sig-algo "ECDSA_secp256k1" \
  --signer "emulator-account"

flow transactions build ./transactions/test.cdc \
  --authorizer owner \
  --proposer owner \
  --payer owner \
  --filter payload \
  --save test.rlp

flow transactions sign ./test.rlp \
  --signer owner \
  --filter payload \
  --save test.signed.rlp

flow transactions send-signed ./test.signed.rlp

Cadence Quirks

1. Iterating over a reference to an array

Initial idea

let numbers = [1, 2, 3]
let numbersRef = &numbers as &[Int]
for number in numbersRef {
  log(number)
}

Produces expected array, got "&[Int]". This trick below works.

let numbers = [1, 2, 3]
let numbersRef = &numbers as &[Int]
for number in numbersRef.concat([]) {
  log(number)
}

2. Using --update with flow project deploy

It does not call init() a second time on the account.