allow toplevel answers to be passed back as queries

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "scryer-prolog"
-version = "0.8.12"
+version = "0.8.13"
 authors = ["Mark Thom <markjordanthom@gmail.com>"]
 repository = "https://github.com/mthom/scryer-prolog"
 description = "A modern Prolog implementation written mostly in Rust."

src/prolog/write.rs

@@ -372,29 +372,23 @@ fn next_step(mut stdout: RawTerminal<std::io::Stdout>) -> ContinueResult
 pub fn print(wam: &mut Machine, result: EvalSession) {
     match result {
         EvalSession::InitialQuerySuccess(alloc_locs, mut heap_locs) => {            
+            loop {
                 if wam.or_stack_is_empty() {
-                println!("true.");
-
                     if heap_locs.is_empty() {
+                        println!("true.");
                         return;
                     }
+                } else if heap_locs.is_empty() {
+                    print!("true");
+                    stdout().flush().unwrap();
                 }
                 
-            if !wam.or_stack_is_empty() {
-                print!("true .");
-
-                if !heap_locs.is_empty() {
-                    println!("\r");
-                }
-            }
-
-            loop {
-                let mut output = PrinterOutputter::new();
-
-                let bindings = wam.heap_view(&heap_locs, output).result();
                 let mut raw_stdout = stdout().into_raw_mode().unwrap();
 
                 if !heap_locs.is_empty() {
+                    let mut output = PrinterOutputter::new();                    
+                    let bindings = wam.heap_view(&heap_locs, output).result();
+                    
                     write!(raw_stdout, "{}", bindings).unwrap();
                     raw_stdout.flush().unwrap();