From 0dcd9e58055a32046e7811e30fb72a0db2825bf2 Mon Sep 17 00:00:00 2001
From: Mark Thom <markjordanthom@gmail.com>
Date: Sun, 27 Oct 2019 14:18:32 -0600
Subject: [PATCH] correct sign/1 (#216)

---
 src/prolog/heap_print.rs                 | 3 ++-
 src/prolog/machine/machine_state_impl.rs | 4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/prolog/heap_print.rs b/src/prolog/heap_print.rs
index 2c1ce6a0..0f9f7985 100644
--- a/src/prolog/heap_print.rs
+++ b/src/prolog/heap_print.rs
@@ -329,7 +329,8 @@ pub fn requires_space(atom: &str, op: &str) -> bool {
             .next()
             .map(|oc| {
                 if ac == '0' {
-                    oc == 'b' || oc == 'x' || oc == 'o' || oc == '\'' || alpha_numeric_char!(oc)
+                    oc == 'b' || oc == 'x' || oc == 'o' || oc == '\''
+                 || oc == '(' || alpha_numeric_char!(oc)
                 } else if alpha_numeric_char!(ac) {
                     oc == '(' || alpha_numeric_char!(oc)
                 } else if graphic_token_char!(ac) {
diff --git a/src/prolog/machine/machine_state_impl.rs b/src/prolog/machine/machine_state_impl.rs
index 5d6b5fbc..0bbdcf38 100644
--- a/src/prolog/machine/machine_state_impl.rs
+++ b/src/prolog/machine/machine_state_impl.rs
@@ -1381,9 +1381,9 @@ impl MachineState {
         if n.is_positive() {
             Integer::from(1)
         } else if n.is_negative() {
-            Integer::from(0)
-        } else {
             Integer::from(-1)
+        } else {
+            Integer::from(0)
         }
     }
 
-- 
2.54.0