Type Alias BoundFunction<TFn, TArgs>

BoundFunction: TArgs extends []
    ? TFn
    : TArgs extends [any]
        ? TFn extends (a0: any, ...args: infer R) => infer RT
            ? (...args: R) => RT
            : (...args: any[]) => ReturnType<TFn>
        : TArgs extends [any, any]
            ? TFn extends (a0: any, a1: any, ...args: infer R) => infer RT
                ? (...args: R) => RT
                : (...args: any[]) => ReturnType<TFn>
            : TArgs extends [any, any, any]
                ? TFn extends (
                    a0: any,
                    a1: any,
                    a2: any,
                    ...args: infer R,
                ) => infer RT
                    ? (...args: R) => RT
                    : (...args: any[]) => ReturnType<TFn>
                : TArgs extends [any, any, any, any]
                    ? TFn extends (
                        a0: any,
                        a1: any,
                        a2: any,
                        a3: any,
                        ...args: infer R,
                    ) => infer RT
                        ? (...args: R) => RT
                        : (...args: any[]) => ReturnType<TFn>
                    : TArgs extends [any, any, any, any, any]
                        ? TFn extends (
                            a0: any,
                            a1: any,
                            a2: any,
                            a3: any,
                            a4: any,
                            ...args: infer R,
                        ) => infer RT
                            ? (...args: R) => RT
                            : (...args: any[]) => ReturnType<TFn>
                        : (...args: any[]) => ReturnType<TFn>

Produces the return type for a function after a prefix of arguments has already been bound.

This implementation is a TypeScript 3.4+ compatible middle ground between:

A fully simplified fallback ((...args: any[]) => ReturnType<TFn>)
A TS 4.0+ variadic tuple implementation (shown below as comments)

It preserves remaining argument inference for up to 5 pre-bound arguments and then falls back to a generic callable return type.

Type Parameters

TFn extends (...args: any[]) => any
The function being bound.
TArgs extends any[]
The tuple of arguments that will be pre-bound.

Since

0.15.0

Type Alias BoundFunction<TFn, TArgs>

Type Parameters

Since

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