From 0903277b692d046cf7f2184dd6b7e167775dfd2d Mon Sep 17 00:00:00 2001
From: greg <greg.shuflin@protonmail.com>
Date: Mon, 29 Jul 2019 19:44:46 -0700
Subject: [PATCH] simple expression

---
 schala-lang/language/src/visitor.rs | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/schala-lang/language/src/visitor.rs b/schala-lang/language/src/visitor.rs
index 4b30da1..a258186 100644
--- a/schala-lang/language/src/visitor.rs
+++ b/schala-lang/language/src/visitor.rs
@@ -1,4 +1,13 @@
+use crate::ast::ExpressionKind;
 
-pub trait ASTVisitor {
-
+pub trait ExpressionKindVisitor<T> {
+  fn nat_literal(&mut self, n: u64) -> T;
+}
+
+pub fn dispatch<T>(input: &mut ExpressionKind, visitor: &mut dyn ExpressionKindVisitor<T>) -> T {
+  use ExpressionKind::*;
+  match input {
+    NatLiteral(n) => visitor.nat_literal(*n),
+    _ => panic!()
+  }
 }