🙏Inspired by EOS Titan flashloans smart contract design.

Borrow any amount of liquidity instantly for zero fees & no collateral.

• Concept
• Examples
• Build
• ACTION borrow
• ACTION savebalance
• ACTION checkbalance
• ACTION callback

1. account calls borrow action from flash.sx with a desired quantity.
   • contract gets initial balance of asset.
   • contract sends quantity to account.
2. account recieves notifications via on_notify and/or callback of incoming transfer.
   • account is free to use received quantity for any purposes.
   • account returns loan back to contract.
3. contract gets final balance of asset
   • contract throws an error if initial balance is lower than final balance.

• basic.cpp (example transaction)
• callback.cpp (example transaction)

$ eosio-cpp flash.sx.cpp -I include

Account requests to borrow quantity

• authority: any

• {name} to - receiver of flash loan
• {name} contract - token contract account
• {asset} quantity - flash loan request amount
• {string} [memo=""] - (optional) transfer memo
• {name} [notifier=""] - (optional) notify accounts after transfer has been sent

const asset quantity = asset{10000, symbol{"EOS", 4}};
flash::borrow_action borrow( "flash.sx"_n, { get_self(), "active"_n });
borrow.send( get_self(), "eosio.token"_n, quantity, "my memo", "notifyme" );

$ cleos push action flash.sx borrow '["myaccount", "eosio.token", "1.0000 EOS", "my memo", "notifyme"]' -p myaccount

Save existing balance of account

• authority: any

• {name} account - account to save balance from
• {map<symbol_code, name>} symcodes - map of symbol code & contract names (ex: [ symbol_code{"EOS"}, "eosio.token"_n ] )

const name account = "myaccount"_n;
map<symbol_code, name> symcodes;
symcodes[symbol_code{"EOS"}] = "eosio.token"_n;

flash::savebalance_action savebalance( "flash.sx"_n, { account, "active"_n });
savebalance.send( account, symcodes );

$ cleos push action flash.sx savebalance '["myaccount", [{"key": "EOS", "value": "eosio.token"}]]' -p myaccount

Throws error if account does not have equal or above previously saved balance

• authority: any

• {name} account - account to check if minimum balance is available
• {map<symbol_code, name>} symcodes - map of symbol code & contract names (ex: [ symbol_code{"EOS"}, "eosio.token"_n ] )

const name account = "myaccount"_n;
map<symbol_code, name> symcodes;
symcodes[symbol_code{"EOS"}] = "eosio.token"_n;

flash::checkbalance_action checkbalance( "flash.sx"_n, { account, "active"_n });
checkbalance.send( account, symcodes );

$ cleos push action flash.sx checkbalance '["myaccount", [{"key": "EOS", "value": "eosio.token"}]]' -p myaccount

Notifies recipient account via callback action after transfer has been sent from borrow action

• authority: get_self()

• {name} to - receiver of flash loan
• {name} contract - token contract account
• {asset} quantity - flash loan request amount
• {string} memo - used for outgoing transfer
• {name} recipient - callback recipient

[[eosio::on_notify("flash.sx::callback")]]
void callback( const name to, const name contract, asset quantity, const string memo, const name recipient )
{
    token::transfer_action transfer( contract, { get_self(), "active"_n });
    transfer.send( get_self(), "flash.sx"_n, quantity, memo );
}