# Packages
# README
x/mint
- Abstract
- Terms
- State
- State Transitions
- Client
- Genesis State
- Params
- Assumptions and Considerations
- Implementation
- References
Abstract
Babylon's x/mint is a fork of the Cosmos SDK
x/mint module that
makes some changes to the inflation mechanism. The code is adapted from
Celestia's mint
module.
Inflation Schedule
| Year | Inflation (%) |
|---|---|
| 0 | 8.00 |
| 1 | 7.20 |
| 2 | 6.48 |
| 3 | 5.832 |
| 4 | 5.2488 |
| 5 | 4.72392 |
| 6 | 4.251528 |
| 7 | 3.8263752 |
| 8 | 3.44373768 |
| 9 | 3.099363912 |
| 10 | 2.7894275208 |
| 11 | 2.51048476872 |
| 12 | 2.259436291848 |
| 13 | 2.0334926626632 |
| 14 | 1.83014339639688 |
| 15 | 1.647129056757192 |
| 16 | 1.50 |
| 17 | 1.50 |
| 18 | 1.50 |
| 19 | 1.50 |
| 20 | 1.50 |
- Year indicates the number of years elapsed since chain genesis.
- Inflation (%) indicates the percentage of the total supply that will be minted in the next year.
Terms
- Inflation Rate: The percentage of the total supply that will be minted
each year. The inflation rate is calculated once per year on the anniversary
of chain genesis based on the number of years elapsed since genesis. The
inflation rate is calculated as
InitialInflationRate * ((1 - DisinflationRate) ^ YearsSinceGenesis). See ./types/constants.go for the constants used in this module. - Annual Provisions: The total amount of tokens that will be minted each
year. Annual provisions are calculated once per year on the anniversary of
chain genesis based on the total supply and the inflation rate. Annual
provisions are calculated as
TotalSupply * InflationRate - Block Provision: The amount of tokens that will be minted in the current
block. Block provisions are calculated once per block based on the annual
provisions and the number of nanoseconds elapsed between the current block and
the previous block. Block provisions are calculated as
AnnualProvisions * (NanosecondsSincePreviousBlock / NanosecondsPerYear)
State
See ./types/minter.go for the Minter struct which
contains this module's state.
State Transitions
The Minter struct is updated every block via BeginBlocker.
Begin Block
See BeginBlocker in ./abci.go.
Events
An event is emitted every block when a block provision is minted. See
mintBlockProvision in ./abci.go.
Client
CLI
$ babylond query mint annual-provisions
80235005639941.760000000000000000
$ babylond query mint genesis-time
2023-05-09 00:56:15.59304 +0000 UTC
$ babylond query mint inflation
0.080000000000000000
Genesis State
The genesis state is defined in ./types/genesis.go.
Params
All params have been removed from this module because they should not be modifiable via governance. The constants used in this module are defined in ./types/constants.go and they are subject to change via hardforks.
Assumptions and Considerations
For the Gregorian calendar, the average length of the calendar year (the mean year) across the complete leap cycle of 400 years is 365.2425 days (97 out of 400 years are leap years).
Source: https://en.wikipedia.org/wiki/Year#Calendar_year
This module assumes DaysPerYear = 365.2425 so when modifying tests, developers
must define durations based on this assumption because ordinary durations won't
return the expected results. In other words:
// oneYear is 31,556,952 seconds which will likely return expected results in tests
oneYear := time.Duration(minttypes.NanosecondsPerYear)
// oneYear is 31,536,000 seconds which will likely return unexpected results in tests
oneYear := time.Hour * 24 * 365
Implementation
See x/mint for the implementation of this module.