leetspeak.go

package main

import (
	"fmt"
	"os"
	"strings"
)

var mapping = map[string]string{
	"a": "4",
	"e": "3",
	"o": "0",
	"l": "1",
	"i": "!",
	"s": "$",
	"t": "7",
}

func main() {
	text := strings.Join(os.Args[1:], " ")

	for k, v := range mapping {
		text = strings.Replace(strings.ToLower(text), k, v, -1)
	}

	fmt.Println(text)
}