tap

tap<K, T>(fn: T[K]): Funcware<MethodOf<HasMethod<K>, K>>

Defined in: ext/funcware/tap.ts:29

Creates funcware that taps into a method call, running a side-effect function after the original method.

Use cases:

• Logging, analytics, or debugging after method execution
• Triggering side effects without altering the original return value
• Composing additional behavior in functional pipelines

Type Parameters

Type Parameter	Description
K extends string	The method name
T extends HasMethod<K>	The target type with the method

Parameters

Parameter	Type	Description
fn	T[K]	The function to run after the original method

Returns

Funcware<MethodOf<HasMethod<K>, K>>

Funcware that runs the side-effect function after the original method

Source

This function is useful for scenarios where you want to observe or react to method calls without changing their result, such as for logging, metrics, or triggering external effects.

export const tap =
  <K extends string, T extends HasMethod<K>>(
    fn: T[K]
  ): Funcware<MethodOf<HasMethod<K>, K>> =>
  (inner) =>
  (...params) => {
    const res = inner(...params);
    fn(...params);
    return res;
  };

Example

const logParams = (...params: any[]) => console.log('Called with:', ...params);
const tapware = tap(logParams);
const original = (x: number) => x * 2;
const tapped = tapware(original);
tapped(5); // Logs 'Called with: 5', returns 10