---
sidebar_position: 1
---

# `x/mint`

## Contents

* [State](#state)
    * [Minter](#minter)
    * [Params](#params)
* [Begin-Block](#begin-block)
    * [NextInflationRate](#nextinflationrate)
    * [NextAnnualProvisions](#nextannualprovisions)
    * [BlockProvision](#blockprovision)
* [Parameters](#parameters)
* [Events](#events)
    * [BeginBlocker](#beginblocker)
* [Client](#client)
        * [CLI](#cli)
        * [gRPC](#grpc)
        * [REST](#rest)

# Concepts

## The Minting Mechanism

The minting mechanism was designed to:

* allow for a flexible inflation rate determined by market demand targeting a particular bonded-stake ratio
* effect a balance between market liquidity and staked supply

In order to best determine the appropriate market rate for inflation rewards, a
moving change rate is used.  The moving change rate mechanism ensures that if
the % bonded is either over or under the goal %-bonded, the inflation rate will
adjust to further incentivize or disincentivize being bonded, respectively. Setting the goal
%-bonded at less than 100% encourages the network to maintain some non-staked tokens
which should help provide some liquidity.

It can be broken down in the following way:

* If the inflation rate is below the goal %-bonded the inflation rate will
   increase until a maximum value is reached
* If the goal % bonded (67% in Cosmos-Hub) is maintained, then the inflation
   rate will stay constant
* If the inflation rate is above the goal %-bonded the inflation rate will
   decrease until a minimum value is reached


# State

## Minter

The minter is a space for holding current inflation information.

* Minter: `0x00 -> ProtocolBuffer(minter)`

```protobuf reference
https://github.com/cosmos/cosmos-sdk/blob/v0.46.0/proto/cosmos/mint/v1beta1/mint.proto#L9-L23
```

## Params

The mint module stores it's params in state with the prefix of `0x01`,
it can be updated with governance or the address with authority.

* Params: `mint/params -> legacy_amino(params)`

```protobuf reference
https://github.com/cosmos/cosmos-sdk/blob/v0.46.0/proto/cosmos/mint/v1beta1/mint.proto#L25-L57
```


# Begin-Block

Minting parameters are recalculated and inflation
paid at the beginning of each block.

## Inflation rate calculation

Inflation rate is calculated using an "inflation calculation function" that's
passed to the `NewAppModule` function. If no function is passed, then the SDK's
default inflation function will be used (`NextInflationRate`). In case a custom
inflation calculation logic is needed, this can be achieved by defining and
passing a function that matches `InflationCalculationFn`'s signature.

```go
type InflationCalculationFn func(ctx sdk.Context, minter Minter, params Params, bondedRatio sdk.Dec) sdk.Dec
```

### NextInflationRate

The target annual inflation rate is recalculated each block.
The inflation is also subject to a rate change (positive or negative)
depending on the distance from the desired ratio (67%). The maximum rate change
possible is defined to be 13% per year, however the annual inflation is capped
as between 7% and 20%.

```go
NextInflationRate(params Params, bondedRatio sdk.Dec) (inflation sdk.Dec) {
	inflationRateChangePerYear = (1 - bondedRatio/params.GoalBonded) * params.InflationRateChange
	inflationRateChange = inflationRateChangePerYear/blocksPerYr

	// increase the new annual inflation for this next cycle
	inflation += inflationRateChange
	if inflation > params.InflationMax {
		inflation = params.InflationMax
	}
	if inflation < params.InflationMin {
		inflation = params.InflationMin
	}

	return inflation
}
```

## NextAnnualProvisions

Calculate the annual provisions based on current total supply and inflation
rate. This parameter is calculated once per block.

```go
NextAnnualProvisions(params Params, totalSupply sdk.Dec) (provisions sdk.Dec) {
	return Inflation * totalSupply
```

## BlockProvision

Calculate the provisions generated for each block based on current annual provisions. The provisions are then minted by the `mint` module's `ModuleMinterAccount` and then transferred to the `auth`'s `FeeCollector` `ModuleAccount`.

```go
BlockProvision(params Params) sdk.Coin {
	provisionAmt = AnnualProvisions/ params.BlocksPerYear
	return sdk.NewCoin(params.MintDenom, provisionAmt.Truncate())
```


# Parameters

The minting module contains the following parameters:

| Key                 | Type            | Example                |
|---------------------|-----------------|------------------------|
| MintDenom           | string          | "uatom"                |
| InflationRateChange | string (dec)    | "0.130000000000000000" |
| InflationMax        | string (dec)    | "0.200000000000000000" |
| InflationMin        | string (dec)    | "0.070000000000000000" |
| GoalBonded          | string (dec)    | "0.670000000000000000" |
| BlocksPerYear       | string (uint64) | "6311520"              |


# Events

The minting module emits the following events:

## BeginBlocker

| Type | Attribute Key     | Attribute Value    |
|------|-------------------|--------------------|
| mint | bonded_ratio      | {bondedRatio}      |
| mint | inflation         | {inflation}        |
| mint | annual_provisions | {annualProvisions} |
| mint | amount            | {amount}           |


# Client

## CLI

A user can query and interact with the `mint` module using the CLI.

### Query

The `query` commands allow users to query `mint` state.

```shell
simd query mint --help
```

#### annual-provisions

The `annual-provisions` command allow users to query the current minting annual provisions value

```shell
simd query mint annual-provisions [flags]
```

Example:

```shell
simd query mint annual-provisions
```

Example Output:

```shell
22268504368893.612100895088410693
```

#### inflation

The `inflation` command allow users to query the current minting inflation value

```shell
simd query mint inflation [flags]
```

Example:

```shell
simd query mint inflation
```

Example Output:

```shell
0.199200302563256955
```

#### params

The `params` command allow users to query the current minting parameters

```shell
simd query mint params [flags]
```

Example:

```yml
blocks_per_year: "4360000"
goal_bonded: "0.670000000000000000"
inflation_max: "0.200000000000000000"
inflation_min: "0.070000000000000000"
inflation_rate_change: "0.130000000000000000"
mint_denom: stake
```

## gRPC

A user can query the `mint` module using gRPC endpoints.

### AnnualProvisions

The `AnnualProvisions` endpoint allow users to query the current minting annual provisions value

```shell
/cosmos.mint.v1beta1.Query/AnnualProvisions
```

Example:

```shell
grpcurl -plaintext localhost:9090 cosmos.mint.v1beta1.Query/AnnualProvisions
```

Example Output:

```json
{
  "annualProvisions": "1432452520532626265712995618"
}
```

### Inflation

The `Inflation` endpoint allow users to query the current minting inflation value

```shell
/cosmos.mint.v1beta1.Query/Inflation
```

Example:

```shell
grpcurl -plaintext localhost:9090 cosmos.mint.v1beta1.Query/Inflation
```

Example Output:

```json
{
  "inflation": "130197115720711261"
}
```

### Params

The `Params` endpoint allow users to query the current minting parameters

```shell
/cosmos.mint.v1beta1.Query/Params
```

Example:

```shell
grpcurl -plaintext localhost:9090 cosmos.mint.v1beta1.Query/Params
```

Example Output:

```json
{
  "params": {
    "mintDenom": "stake",
    "inflationRateChange": "130000000000000000",
    "inflationMax": "200000000000000000",
    "inflationMin": "70000000000000000",
    "goalBonded": "670000000000000000",
    "blocksPerYear": "6311520"
  }
}
```

## REST

A user can query the `mint` module using REST endpoints.

### annual-provisions

```shell
/cosmos/mint/v1beta1/annual_provisions
```

Example:

```shell
curl "localhost:1317/cosmos/mint/v1beta1/annual_provisions"
```

Example Output:

```json
{
  "annualProvisions": "1432452520532626265712995618"
}
```

### inflation

```shell
/cosmos/mint/v1beta1/inflation
```

Example:

```shell
curl "localhost:1317/cosmos/mint/v1beta1/inflation"
```

Example Output:

```json
{
  "inflation": "130197115720711261"
}
```

### params

```shell
/cosmos/mint/v1beta1/params
```

Example:

```shell
curl "localhost:1317/cosmos/mint/v1beta1/params"
```

Example Output:

```json
{
  "params": {
    "mintDenom": "stake",
    "inflationRateChange": "130000000000000000",
    "inflationMax": "200000000000000000",
    "inflationMin": "70000000000000000",
    "goalBonded": "670000000000000000",
    "blocksPerYear": "6311520"
  }
}
```