typocomath/src/generic/arithmetic.ts

import type {Dependencies, Signature} from '../interfaces/type.js'
import {$$typeToString} from 'ts-macros'

export const square =
   <T>(dep: Dependencies<'multiply', T>): Signature<'square', T> =>
   z => dep.multiply(z, z)
   // z => dep.fooBar(z, z) // fails as desired
   // z => dep.multiply(z, 'foo') // still fails as desired

// make sure ts-macros is running
function $contains<T>(value: T, ...possible: Array<T>) {
    // repetition which goes over all the elements in the "possible" array
    return +["||", [possible], (item: T) => value === item];
}

const searchItem = "needle";
console.log("In generic arithmetic")
console.log($contains!(searchItem, "erwin", "tj")); 
// Transpiles to: console.log(false);

// OK, record the type of square:
square.reflectedType = $$typeToString!<typeof square>();

type ShallowExpand<T> =  T extends unknown ? { [K in keyof T]: T[K] } : never;
type ExpandedParameters<T extends (...args: any) => any> = {[Index in keyof Parameters<T>]: ShallowExpand<Parameters<T>[Index]>}
type ExpandTwice<T extends any[]> = {[Index in keyof T] : ShallowExpand<T[Index]>}
type AsArray<T> = T extends any[] ? T : [];
type DeepExpand<T> =
   T extends (...args: any) => any ? (...pars: AsArray<DeepExpand<Parameters<T>>>) => DeepExpand<ReturnType<T>> :
   T extends unknown ? { [K in keyof T]: DeepExpand<T[K]> } : never;
type Out<T> = ShallowExpand<Dependencies<'multiply', T>>;

console.log("Deps type is", $$typeToString!<<T>() => Out<T>>())

type OutB = ExpandTwice<Parameters<typeof square>>;

console.log("Or perhaps", $$typeToString!<OutB>())

console.log("Or maybe even", $$typeToString!<
            <T>(...args: DeepExpand<Parameters<typeof square<T>>>) => DeepExpand<ReturnType<typeof square<T>>>
            >())