Add Display impl for FQSN

schala-lang/language/src/symbol_table/mod.rs

@@ -83,6 +83,19 @@ impl Fqsn {
     }
 }
 
+impl fmt::Display for Fqsn {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let delim = "::";
+        let Fqsn { scopes } = self;
+        write!(f, "FQSN<{}", scopes[0])?;
+        for item in scopes[1..].iter() {
+            write!(f, "{}{}", delim, item)?;
+        }
+        write!(f, ">")
+    }
+}
+
+
 //TODO eventually this should use ItemId's to avoid String-cloning
 /// One segment within a scope.
 #[derive(Debug, Clone, Eq, PartialEq, Hash, PartialOrd, Ord)]
@@ -90,6 +103,13 @@ enum Scope {
     Name(Rc<String>),
 }
 
+impl fmt::Display for Scope {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let Scope::Name(name) = self;
+        write!(f, "{}", name)
+    }
+}
+
 #[allow(dead_code)]
 #[derive(Debug, Clone)]
 pub enum SymbolError {