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export type Op = string | { op: string; a: Op; b: Op };
export type Rewrite<left extends Op, right extends Op> = {
type: 'rewrite';
left: left;
right: right;
};
export type Flip<R extends Rewrite<Op, Op>> = Rewrite<R['right'], R['left']>;
export type ApplyRewrite<O extends Op, R extends Rewrite<Op, Op>> =
O extends R['left'] ? R['right']
: O extends string ? O
: O extends { a: Op, b: Op, op: string } ? (
ApplyRewrite<O['a'], R> extends O['a']
? Omit<O, 'b'> & { b: ApplyRewrite<O['b'], R> }
: Omit<O, 'a'> & { a: ApplyRewrite<O['a'], R> }
)
: never;
export interface Kind<V = unknown, R = unknown> {
_: V;
return: R;
}
export type Ap<K extends Kind, V> = (K & { _: V })['return'];
export type ChainRewrites<Rws extends Rewrite<Op, Op>[], O extends Op> =
Rws extends [] ? O
: Rws extends [infer R extends Rewrite<Op, Op>, ...infer Rs extends Rewrite<Op, Op>[]]
? ChainRewrites<Rs, ApplyRewrite<O, R>>
: never;
export type VerifyEquation<Eq extends Rewrite<Op, Op>> =
Eq['right'] extends 'true' ? true : false & Eq['right'];
export type Eq<a, b> = ([a] extends [b] ? ([b] extends [a] ? true : false & { lhs: a; rhs: b }) : false & { lhs: a; rhs: b });
export type Equation<A extends Op, B extends Op> = { op: '=', a: A, b: B };
export type Refl<A extends Op> = Rewrite<Equation<A, A>, 'true'>;
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