柯里化函数类型

https://medium.com/codex/currying-in-typescript-ca5226c85b85

// 函数范型，部分开始参数
function curry<FN extends (...args: any[]) => any, STARTING_ARGS extends PartialParameters<FN>>(
  targetFn: FN,
  ...existingArgs: STARTING_ARGS
): CurriedFunction<STARTING_ARGS, FN> {
  return function (...args) {
    const totalArgs = [...existingArgs, ...args];
    if (totalArgs.length >= targetFn.length) {
      return targetFn(...totalArgs);
    }
    return curry(targetFn, ...(totalArgs as PartialParameters<FN>));
  };
}




// 柯里化后的返回值，参数（NEW_ARGS）是剩余参数的一部分，如果参数不够则需要迭代
type CurriedFunction<PROVIDED extends any[], FN extends (...args: any[]) => any> = <
  NEW_ARGS extends PartialTuple<RemainingParameters<PROVIDED, Parameters<FN>>>,
>(
  ...args: NEW_ARGS
) => CurriedFunctionOrReturnValue<[...PROVIDED, ...NEW_ARGS], FN>;

// 没有剩余参数时返回函数返回值，否则返回多了已有参数的柯里化函数

type CurriedFunctionOrReturnValue any> = RemainingParameters<

PROVIDED,

Parameters

> extends [any, ...any[]]

? CurriedFunction

: ReturnType;

// 转换为可选元组

type PartialTuple =

// If the tuple provided has at least one required value

TUPLE extends [infer NEXT_PARAM, ...infer REMAINING]

? // recurse back in to this type with one less item

// in the original tuple, and the latest extracted value

// added to the extracted list as optional

PartialTuple

: // else if there are no more values,

// return an empty tuple so that too is a valid option

[...EXTRACTED, ...TUPLE];

// 获取部分参数（可选）

type PartialParameters any> = PartialTuple>;

// 获取剩余参数，提供的参数类型必须符合期望参数类型

type RemainingParameters =

// if the expected array has any required items…

EXPECTED extends [infer E1, ...infer EX]

? // if the provided array has at least one required item

PROVIDED extends [infer P1, ...infer PX]

? // if the type is correct, recurse with one item less

//in each array type

P1 extends E1

? RemainingParameters

: // else return this as invalid

never

: // else the remaining args is unchanged

EXPECTED

: // else there are no more arguments

[];