Added repl and very basic parser

cmd/main.go

@@ -1,7 +1,13 @@
 package main
 
-import "fmt"
+import (
+	"fmt"
+	"os"
+)
 
 func main() {
-	fmt.Println("Hellow world")
+	user := "user"
+
+	fmt.Printf("Hello %s, this is butter :)))\n", user)
+	ReplStart(os.Stdin, os.Stdout)
 }

cmd/repl.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+)
+
+const PROMPT = ">>"
+
+func ReplStart(in io.Reader, out io.Writer) {
+	scanner := bufio.NewScanner(in)
+
+	for {
+		fmt.Print(PROMPT)
+
+		scanned := scanner.Scan()
+		if !scanned {
+			return
+		}
+
+		line := scanner.Text()
+
+		l := NewLexer(line)
+
+		for tok := l.NextToken(); tok.Type != EOF; tok = l.NextToken() {
+			fmt.Printf("%+v\n", tok)
+		}
+	}
+}