Add file operations

builtins/write.go

@@ -0,0 +1,28 @@
+package builtins
+
+import (
+	"monkey/object"
+	"monkey/typing"
+	"syscall"
+)
+
+// Write ...
+func Write(args ...object.Object) object.Object {
+	if err := typing.Check(
+		"write", args,
+		typing.ExactArgs(2),
+		typing.WithTypes(object.INTEGER_OBJ, object.INTEGER_OBJ),
+	); err != nil {
+		return newError(err.Error())
+	}
+
+	fd := int(args[0].(*object.Integer).Value)
+	data := []byte(args[1].(*object.String).Value)
+
+	n, err := syscall.Write(syscall.Handle(fd), data)
+	if err != nil {
+		return newError("IOError: %s", err)
+	}
+
+	return &object.Integer{Value: int64(n)}
+}