catnipan
/ useStateWithAction.ts
Last active
February 8, 2024 21:21
state machine: add handler to state in a type safe way
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| type AnyState = { step: string }; | |
| type AnyActionMap = Record<string, (...args: any[]) => unknown>; | |
| type AnyAction<State extends AnyState> = { | |
| [S in State['step']]?: ( | |
| state: { step: S } & State, | |
| setState: (newState: SetStateAction<State>) => void | |
| ) => AnyActionMap; | |
| }; | |
| type StateWithActions< |
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| // Credit to https://danielkeep.github.io/practical-intro-to-macros.html | |
| macro_rules! count_exprs { | |
| () => (0); | |
| ($head:expr $(, $tail:expr)*) => (1 + count_exprs!($($tail),*)); | |
| } | |
| macro_rules! recurrence { | |
| ( $seq:ident [ $ind:ident ]: $sty:ty = $recur:expr, $($inits:expr),+) => { | |
| { |