This is a simple flashcard app. With flags to control the sides of the flashcards and the number of flashcards in the session.

All the flashcards without any input at the prompt, are deleted from the map. And ones with an input, remain. The idea is that, the user marks the flashcard that they want to revise in case they had forgotten it, later in the session.

The outer loop, loops until the length of the map is >= 1

package main

import (
 "encoding/csv"
 "flag"
 "fmt"
 "log"
 "math/rand"
 "os"
 "os/exec"
 "runtime"
 "time"

 "github.com/fatih/color"
)

var (
 flagNoColor = flag.Bool("no-color", false, "disable color output")
 csvPath = flag.String("src", "src.csv", "source")
 side = flag.Int("s", -1, "side")
 num = flag.Int("n", -1, "number")
)

var clear map[string]func()

func init() 
 clear = make(map[string]func())
 clear["linux"] = func() 
 cmd := exec.Command("clear")
 cmd.Stdout = os.Stdout
 cmd.Run()
 
 clear["windows"] = func() 
 cmd := exec.Command("cmd", "/c", "cls")
 cmd.Stdout = os.Stdout
 cmd.Run()
 


func CallClear() 
 value, ok := clear[runtime.GOOS]
 if ok 
 value()
 else 
 panic("Panic!")
 


func random(min int, max int) int 
 return rand.Intn((max-min) + 1) + min


func main() 

 flag.Parse()

 file, err := os.Open(*csvPath)
 if err != nil 
 log.Println(err)
 return
 
 defer file.Close()

 csvReader := csv.NewReader(file)

 csvData, err := csvReader.ReadAll()
 if err != nil 
 log.Println(err)
 return
 

 qaRaw := make(map[string]string, len(csvData))
 for _, data := range csvData 
 qaRaw[data[0]] = data[1]
 

 qaPair := make(map[string]string)

 if *num != -1 
 i := 1
 for one, two := range qaRaw 
 if i <= *num 
 qaPair[one] = two
 
 i++
 
 else 
 for one, two := range qaRaw 
 qaPair[one] = two
 
 

 done := make(chan bool)

 go func() 
 if *flagNoColor 
 color.NoColor = true
 
 white := color.New(color.FgWhite)
 boldWhite := white.Add(color.Bold)

 qNum := 0

 for len(qaPair) >= 1 
 for one, two := range qaPair 
 rand.Seed(time.Now().UnixNano())
 randomNum := random(1, 2)
 if *side != -1 
 randomNum = *side
 
 var userInput string
 CallClear()
 boldWhite.Printf("n #t%d / %dn", qNum+1, qNum+len(qaPair))
 qNum++
 if randomNum == 1 
 boldWhite.Printf("n Qt%s", one)
 fmt.Scanln(&userInput)
 boldWhite.Printf("n At%s", two)
 fmt.Scanln(&userInput)
 if len(userInput) == 0 
 delete(qaPair, one)
 
 else if randomNum == 2 
 boldWhite.Printf("n Qt%s", two)
 fmt.Scanln(&userInput)
 boldWhite.Printf("n At%s", one)
 fmt.Scanln(&userInput)
 if len(userInput) == 0 
 delete(qaPair, one)
 
 
 CallClear()
 
 
 done <- true
 ()

 select 
 case <-done:
 fmt.Println("blah blah blah")
 

Flashcards example data (.csv file)

"hola","hi"
"sí","yes"
"¿qué pasa?","what's up?"
"¡vamos!","let's go!"
"¡salud!","cheers!; bless you!"
"no","no"
"por favor","please"
"lo siento","I'm sorry"
"buenos días","good morning"
"buenas noches","good night"
"gracias","thank you"
"vale","okay"
"hasta luego","see you later"
"adiós","goodbye"
"cómo","how (questions)"

var clear map[string]func()

To handle OS specific implementations you may consider using Golang tags feature. See it in action:

flashcard_windows.go

// +build windows

package main

import(
 "os"
 "os/exec"
)

func Clear() 
 cmd := exec.Command("cmd", "/c", "cls")
 cmd.Stdout = os.Stdout
 cmd.Run()

flashcard_unix.go

// +build linux

package main

import(
 "os"
 "os/exec"
)

func Clear() 
 cmd := exec.Command("clear")
 cmd.Stdout = os.Stdout
 cmd.Run()

To build run go build with -tags windows or -tags linux arguments.

Now there is no need call panic(). go build will exit if implementation of Clear function is missing.

See this for more information.