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Currying

Function currying is a concept from functional programming and involves partial application of functions. It allows a function with multiple arguments to be transformed into a sequence of functions, each taking a single argument.

Let's simulate this behavior. For example:

func main() {
  squareFunc := selfMath(multiply)
  doubleFunc := selfMath(add)

  fmt.Println(squareFunc(5))
  // prints 25

  fmt.Println(doubleFunc(5))
  // prints 10
}

func multiply(x, y int) int {
  return x * y
}

func add(x, y int) int {
  return x + y
}

func selfMath(mathFunc func(int, int) int) func (int) int {
  return func(x int) int {
    return mathFunc(x, x)
  }
}

In the example above:

selfMath(multiply) returns a new function and stores it in squareFunc; it doesn't run multiply yet.
squareFunc(5) runs the returned function, which calls multiply(5, 5).

Assignment

The Textio API needs a very robust error-logging system so we can see when things are going awry in the back-end system. We need a function that can create a custom "logger" (a function that prints to the console) given a specific formatter.

These errors are test data, not runtime failures.

Complete the getLogger function. It should take as input a formatter function and return a new function. The new logger function takes as input two strings and passes them to the formatter, then prints the result. Keep the order of the strings.