1 files changed, 35 insertions, 0 deletions
diff --git a/interpreter/repl.go b/interpreter/repl.go
new file mode 100644
index 0000000..73af8a7
--- /dev/null
+++ b/interpreter/repl.go
@@ -0,0 +1,35 @@
+package interpreter
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+
+	"github.com/mvertes/parscan/scanner"
+)
+
+// Repl executes an interactive line oriented Read Eval Print Loop (REPL).
+func (i *Interp) Repl(in io.Reader) (err error) {
+	liner := bufio.NewScanner(in)
+	text, prompt := "", "> "
+	fmt.Print(prompt)
+	for liner.Scan() {
+		text += liner.Text()
+		res, err := i.Eval(text + "\n")
+		switch {
+		case err == nil:
+			if res.IsValid() {
+				fmt.Println(": ", res)
+			}
+			text, prompt = "", "> "
+		case errors.Is(err, scanner.ErrBlock):
+			prompt = ">> "
+		default:
+			fmt.Println("Error:", err)
+			text, prompt = "", "> "
+		}
+		fmt.Print(prompt)
+	}
+	return err
+}