Fix implication parser and output

src/format.rs

@@ -66,6 +66,18 @@ impl Precedence for crate::Formula
 	}
 }
 
+impl std::fmt::Debug for crate::ImplicationDirection
+{
+	fn fmt(&self, format: &mut std::fmt::Formatter) -> std::fmt::Result
+	{
+		match &self
+		{
+			crate::ImplicationDirection::LeftToRight => write!(format, "left to right"),
+			crate::ImplicationDirection::RightToLeft => write!(format, "right to left"),
+		}
+	}
+}
+
 impl std::fmt::Debug for crate::SpecialInteger
 {
 	fn fmt(&self, format: &mut std::fmt::Formatter) -> std::fmt::Result
@@ -391,14 +403,15 @@ impl<'formula> std::fmt::Debug for FormulaDisplay<'formula>
 			},
 			crate::Formula::Implies(crate::Implies{direction, antecedent, implication}) =>
 			{
-				let operator_symbol = match direction
+				match direction
 				{
-					crate::ImplicationDirection::LeftToRight => "->",
-					crate::ImplicationDirection::RightToLeft => "<-",
+					crate::ImplicationDirection::LeftToRight =>
+						write!(format, "{:?} -> {:?}", display_formula(antecedent, precedence),
+							display_formula(implication, precedence))?,
+					crate::ImplicationDirection::RightToLeft =>
+						write!(format, "{:?} <- {:?}", display_formula(implication, precedence),
+							display_formula(antecedent, precedence))?,
 				};
-
-				write!(format, "{:?} {} {:?}", display_formula(antecedent, precedence),
-					operator_symbol, display_formula(implication, precedence))?;
 			},
 			crate::Formula::IfAndOnlyIf(arguments) =>
 			{