How Can I Apply a Function to Every Element in a Go List Efficiently?

Efficient Function Application to Lists in Go

To apply a function to every element in a Go list and store the results in a new list, the traditional approach involves looping over the input list and appending the results to the output list. However, with Go 1.18 and above, there is a more concise and generic solution: the Map function.

The Map function takes a list of elements of type T and a function that converts each element into a value of type V. It returns a new list of type []V containing the results of applying the function to each element in the input list.

Here's an example:

func Map[T, V any](ts []T, fn func(T) V) []V {
    result := make([]V, len(ts))
    for i, t := range ts {
        result[i] = fn(t)
    }
    return result
}

// Usage example
input := []int{4, 5, 3}
outputInts := Map(input, func(item int) int { return item + 1 })
outputStrings := Map(input, func(item int) string { return fmt.Sprintf("Item:%d", item) })

In this example, input is a list of integers. We can apply the Map function with two different functions to create a list of incremented integers (outputInts) and a list of formatted strings (outputStrings). This eliminates the need for explicit looping and provides a concise and efficient alternative to the traditional approach.

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