From: Mark Thom <markjordanthom@gmail.com>
Date: Mon, 6 Nov 2017 17:45:27 +0000 (-0700)
Subject: instantiated vars in arithmetic exprs
X-Git-Tag: v0.8.110~680
X-Git-Url: https://git.sagredo.dev/?a=commitdiff_plain;h=4cc340980985b1b193114e847519ab20d2fe81d0;p=scryer-prolog.git

instantiated vars in arithmetic exprs
---

diff --git a/src/prolog/codegen.rs b/src/prolog/codegen.rs
index dc5a4c15..ad0f4138 100644
--- a/src/prolog/codegen.rs
+++ b/src/prolog/codegen.rs
@@ -306,6 +306,20 @@ impl<'a, TermMarker: Allocator<'a>> CodeGenerator<'a, TermMarker>
                         });
                     },
                     &QueryTermRef::Is(terms) => {
+                        let mut target = Vec::new();
+                        self.marker.advance(term_loc, *term);
+
+                        // instantiate any vars introduced in the expr.
+                        for term_ref in terms[1].post_order_iter() {
+                            if let TermRef::Var(lvl, vr, name) = term_ref {
+                                self.marker.mark_var(name, lvl, vr,  term_loc, &mut target);                                
+                            }
+                        }
+
+                        if !target.is_empty() {
+                            code.push(Line::Query(target));
+                        }
+                        
                         let mut evaluator = ArithmeticEvaluator::new();
 
                         let mut arith_code = evaluator.eval(terms[1].as_ref())?;