erc20-demurrage-token

ERC20 token with redistributed continual demurrage
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commit 4d60ecdf5283debb48c1e38ef1e3fabb5c8c1675
parent ed9d9b3833156ee471eaae0296c4107a15abd4d4
Author: Will Ruddick <willruddick@gmail.com>
Date:   Thu,  4 Feb 2021 13:56:33 +0000

Merge branch 'usecase' into 'master'

added use case example and small clarifications

See merge request grassrootseconomics/sarafu-token!1
Diffstat:
MREADME.md | 49+++++++++++++++++++++++++++++++++++++------------
1 file changed, 37 insertions(+), 12 deletions(-)

diff --git a/README.md b/README.md @@ -1,26 +1,50 @@ # RedistributedDemurrageToken +## Use Case +* Network / Basic Income Token + * 100 Sarafu is distributed to anyone in Kenya after user validation by the owner of a faucet which mints new Sarafu. + * Validated users are those that validate their phone number in Kenya. + * A monthly Sarafu holding tax (demurrage) of 2% is deducted from users + * Each month (after a number of blocks) the total amount tax is distributed evenly out to _active_ users. + * any single transaction by a user is considered _active_ (heartbeat) (possibly add minimum size of heartbeat in constructor (TODO)) + * This is meant to result in a disincentivization to hold (hodl) the Sarafu token and increase its usage as a medium of excahnge rather than a store of value. + + +## Variables + +* Inputs to Constructor (Set only once during contract deployment can't be changed ) + * `Demmurage` aka Decay amount: A percentage of token supply that will be charged once per - aka `period` and evenly redistributed to _active_ users + * Demmurage Period (blocks)- aka `period`: The number of blocks (equivalent to a time frame) over which a new Holding Fee is applied and redistributed. + * Inflated Balance: The inflated balance of each user is stored for bookkeeping. + * Number of Decimals: Resolution on token (TODO) (Default 6) + * Minimum Activity Volume: (TODO) the minimum transaction amount to be considered active + * Sink Token Address: Rounding errors and if no one trades the tax goes to this address + + ## Ownership * Contract creator is owner -* Ownership can be transferred (also to ownership void contract) +* Ownership can be transferred (also to ownership void contract "no more changes can be made") ## Mint * Owner can add minters - - A faucet contract would be a minter + - A faucet contract would be a minter and choose the amount of tokens to mint and distribute to new _validated_ users. + - The interface says the amount and is at the caller's discretion per contract call. _validation_ is outside of this contract. * Minters can mint any amount ## Demurrage - -* Decay amount (ppm) and period (blocks) is set at deploy time. - - Cannot be changed -* Tax is applied when a **mint** or **transfer** is triggered for first time in new period; +* Holding Tax (`demurrage`) is applied when a **mint** or **transfer** is triggered for first time/block in a new `period`; (it can also be triggered explicitly) - Supply _stays the same_. - - Updates `demurrageModiifer` which represents an exponential decay step. + - Updates `demurrageModifier` which represents the accumulated tax value and is an exponential decay step (of size `demurrage`) for each `period` + - `demurrageModifier = (1-demurrage)^period` + - e.g. a `demurrage` of 2% at a `period` of 0 would be give a `demurrageModifier= (1-0.02)^0 = 1-1 = 0`. + - e.g. a `demurrage` of 2% at a `period` of 1 would be give a `demurrageModifier = (1-0.02)^1 = 0.98`. + - e.g. a `demurrage` of 2% at a `period` of 2 would be give a `demurrageModifier = (1-0.02)^2 = 0.9604`. * All client-facing values (_balance output_ , _transfer inputs_) are adjusted with `demurrageModifier`. + - e.g. `_balance output_ = user_balance - user_balance * demurrageModifier` * Edge case: `approve` call, which may be called on either side of a period. @@ -28,14 +52,15 @@ * One redistribution entry is added to storage for each period; - When `mint` is triggered, the new totalsupply is stored to the entry - - When `transfer` is triggered, and the account did not yet participate in the period, the entry's participant count is incremented. + - When `transfer` is triggered, and the account did not yet participate in the `period`, the entry's participant count is incremented. * Account must have "participated" in a period to be redistribution beneficiary. * Redistribution is applied when an account triggers a **transfer** for the first time in a new period; - - Check if have participated in period. - - Balance is increased by `(total supply at end of period * demurrage modifier ) / number of participants` - - Participation field is zeroed out. + - Check if user has participated in `period`. (_active_ user heartbeat) + - Each _active_ user balance is increased by `(total supply at end of period * demurrageModifier ) / number_of_active_participants` via minting + - Participation field is zeroed out for that user. * Fractions must be rounded down (TODO) - - Remainder is "dust" and should be sent to a dedicated "sink" address (TODO) + - Remainder is "dust" and should be sent to a dedicated "sink" token address (TODO) + - If no one is _active_ all taxes go to the same sink address ## Data structures