print certain atoms in single quotes.

2018-05-16 20:34:53 -06:00
parent 3f3fcc34c4
commit ddb79e6b34
1 changed files with 5 additions and 1 deletions
--- a/src/prolog/ast.rs
+++ b/src/prolog/ast.rs
@@ -552,7 +552,11 @@ impl fmt::Display for Constant {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            &Constant::Atom(ref atom) =>
-                write!(f, "{}", atom),
+                if atom.as_str().chars().any(|c| ".$'\" ".contains(c)) {
+                    write!(f, "'{}'", atom.as_str())
+                } else {
+                    write!(f, "{}", atom.as_str())
+                },
            &Constant::Char(c) =>
                write!(f, "'{}'", c as u8),
            &Constant::EmptyList =>