import {Map} from '../Iteration/Map'
import {Iteration} from './Iteration'
import {NumberMap} from '../Iteration/Maps/Number'

/**
Move `I`'s position backwards
@param I to move
@param IMap to operate with another set of numbers
@returns [[Iteration]]
@example
```ts
import {I} from 'ts-toolbelt'

type i = I.IterationOf<'20'>

type test0 = I.Pos<i>         // 20
type test1 = I.Pos<I.Prev<i>> // 19
```
*/
export type Prev<I extends Iteration, IMap extends Map = NumberMap> =
    IMap[1][I[0]] // continues iterating