Higher order functions

balance.go

package main

import (
	"fmt"
)


func balanceFormula(paidLate bool) func(float64, float64) float64 {
  if(paidLate == true){
	fn := func(principal float64, lateFee float64) float64{
	  balance := principal + lateFee
	  return balance
	}
	return fn
  }else{
        fn := func(principal float64, lateFee float64) float64{
          //balance := principal
	  return principal
	}
	return fn
  }

}

func main() {
	principal := 1000.00
        lateFee := 50.00  

	formula := balanceFormula(false)
	balance := formula(principal, lateFee)
	
	fmt.Println(balance)
	
}

balance2.go

package main

import (
	"fmt"
)

type CustomerAccount struct{
        Name string
	PaidLate bool
	Principal float64
	LateFee float64
}


func balanceFormula(paidLate bool) func(float64, float64) float64 {
  if(paidLate == true){
	fn := func(principal float64, lateFee float64) float64{
	  balance := principal + lateFee
	  return balance
	}
	return fn
  }else{
        fn := func(principal float64, lateFee float64) float64{
	  return principal
	}
	return fn
  }

}

func main() {

	//late payment
	customer1 := CustomerAccount{"Melvin", true, 1000.00, 50.00}
	
	//payment is on-time
	customer2 := CustomerAccount{"Dave", false, 1000.00, 50.00}
	
	fmt.Printf("Customer balance of customer %s is %f\n", customer1.Name, balanceFormula(customer1.PaidLate)(customer1.Principal, customer1.LateFee))
	fmt.Printf("Customer balance of customer %s is %f", customer2.Name, balanceFormula(customer2.PaidLate)(customer2.Principal, customer2.LateFee))
	
}

main.go

package main

import (
	"fmt"
)

func operate(x int, y int, operator func(x int, y int) int) int{
  return operator(x,y)
}

func main() {
	x := 10
	y := 5 
	
	adder := func(x int, y int) int{
 	 return x + y
	}
	
	subtractor := func(x int, y int) int{
 	 return x - y
	}	
		
	fmt.Println(operate(x, y, adder))
	fmt.Println(operate(x, y, subtractor))
	
}

savefile.go

package main

import (
	"fmt"
)

type MyFile struct{
	Name string
	Base64 string
}

func main() {

	myFile := MyFile{"test.pdf", "base64 encoded file"}

	s3 := func(file MyFile) bool{
	  fmt.Printf("\nSaving %s file implementation to S3", file.Name)
	  return true
	}
	
	blob := func(file MyFile) bool{
	  fmt.Printf("\nSaving %s file to blob storage",  file.Name)
	  return true 
	}
	
	fs := func(file MyFile) bool{
	  fmt.Printf("\nSaving %s file to disk",  file.Name)
	  return true 
	}
	
	processSave(myFile, s3)
	processSave(myFile, blob) 
	processSave(myFile, fs) 
	
}


func processSave(file MyFile, save func(file MyFile) bool){
	save(file)
}