Explain the use of Go's function currying and partial application for creating and using partially applied functions in Go programs?

The use of Go's function currying and partial application are as follows:

Function currying and partial application are techniques used to create new functions by partially applying existing functions.

Function currying refers to the technique of breaking down a function that takes multiple arguments into a sequence of functions that each take a single argument. The resulting functions can be used to create more specific functions by partially applying some of the arguments.

For example, consider a function that calculates the area of a rectangle given its length and width:

func rectangleArea(length, width float64) float64 {
    return length * width
}

Using currying, we can transform this function into a series of functions that each take a single argument:

func rectangleAreaCurried(length float64) func(float64) float64 {
    return func(width float64) float64 {
        return length * width
    }
}

Now we can create a new function that calculates the area of a rectangle with a fixed length:

areaWithLength2 := rectangleAreaCurried(2.0)
area := areaWithLength2(3.0)

Partial application is similar to currying, but it involves fixing some of the arguments of a function, rather than breaking it down into a sequence of functions.

For example, consider a function that takes three arguments:

func add(a, b, c int) int {
    return a + b + c
}

Using partial application, we can create a new function that takes only two arguments:

func addWithTwo(a, b int) int {
    return add(a, b, 2)
}

Now we can use the **addWithTwo** function as if it were a separate function that only takes two arguments:

result := addWithTwo(1, 2) // equivalent to add(1, 2, 2)

In Go, function currying and partial application can be implemented using closures and anonymous functions.