From 8110651ccf498bcf3f0cd55f3b1730d9972cf254 Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Fri, 22 Mar 2019 18:12:13 +0100
Subject: Handle quoted labels

---
 dhall_core/src/printer.rs | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

(limited to 'dhall_core/src/printer.rs')

diff --git a/dhall_core/src/printer.rs b/dhall_core/src/printer.rs
index 7b108d5..508c1c8 100644
--- a/dhall_core/src/printer.rs
+++ b/dhall_core/src/printer.rs
@@ -285,6 +285,21 @@ impl Display for Const {
     }
 }
 
+impl Display for Label {
+    fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+        let s = String::from(self.clone());
+        let is_keyword = |s| match s {
+            "let" | "in" | "if" | "then" | "else" => true,
+            _ => false,
+        };
+        if s.chars().all(|c| c.is_ascii_alphanumeric()) && !is_keyword(&s) {
+            write!(f, "{}", s)
+        } else {
+            write!(f, "`{}`", s)
+        }
+    }
+}
+
 impl Display for Import {
     fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
         use std::path::PathBuf;
-- 
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