curry.ts

export type Curry<F extends (...args: readonly unknown[]) => unknown> = 
  Parameters<F> extends readonly [infer First, ...infer Rest]
    ? (arg: First) => Rest extends readonly []
      ? ReturnType<F>
      : Curry<(...args: Rest) => ReturnType<F>>
    : ReturnType<F>;

export function curry<F extends (...args: readonly unknown[]) => unknown>(fn: F): Curry<F> {
  function curried(...providedArgs: readonly unknown[]): unknown {
    if (providedArgs.length >= fn.length) {
      return fn(...(providedArgs.slice(0, fn.length) as Parameters<F>));
    }
    
    return (...newArgs: readonly unknown[]) => {
      return curried(...providedArgs, ...newArgs);
    };
  }
  
  return curried as Curry<F>;
}