non-parasitic-use-of-Augur-oracle.ts

// Augur's oracle can be used to bring information on-chain,
// allowing money to move automatically based on real-world facts.

// Augur's oracle is secure so long as money that depends on Augur
// is properly tracked in the Augur system.

// Money that depends on Augur's oracle, but isn't tracked in Augur,
// is said to be "parasitic" and is at risk of attack and a threat
// to Augur itself.

// Happily, any project that uses Augur's oracle can write a thin
// wrapper around Augur to properly track money and avoid being
// parasitic.

// Here is an example algorithm for an Ethereum smart contract
// showing how to wrap Augur and properly track money:

// (Augur's Forecast Foundation may one day provide a standardized
// wrapper as a platform component. If you want this please get in
// touch @AugurProject.)

function useOracle(
  money, // money whose destination depends on Augur
  marketId, // the Augur market question whose answer will route the money, eg. "Will the Patriots win the 2019 Super Bowl?"
  moneyDestinationIfYes, // money transferred to this address if Patriots win the Super Bowl
  moneyDestinationIfNo, // money transferred to this address if Patriots lose the Super Bowl
  moneyDestinationIfInvalid) { // money transferred to this address if Augur market deemed invalid
  const { yesShare, noShare, invalidShare } = marketId.makeCompleteSets(money)
  // After market resolves:
  switch(marketId resolution) {
    case yes => send(marketId.redeem(yesShare), moneyDestinationIfYes)
    case no => send(marketId.redeem(noShare), moneyDestinationIfNo)
    case invalid => send(marketId.redeem(invalidShare), moneyDestinationIfInvalid)
  }
}

// We can think of wrapper as a bit like a javascript Promise,
// it can route money even if the underlying Augur market
// resolved a long time ago. In javascript we can do
// `anonymousPromise.then(onSuccess, onFailure)` and in fact
// the Promise might already be resolved but caller doesn't have
// to worry about that.
      
// See the Augur whitepaper for further reading: https://www.augur.net/whitepaper.pdf