Less memory allocations at runtime

tests/forth/harness.rs

@@ -90,7 +90,7 @@ pub fn expect_int(script: &str, expected: i64) {
 }
 
 pub fn expect_str(script: &str, expected: &str) {
-    expect_stack(script, &[Value::Str(expected.to_string(), None)]);
+    expect_stack(script, &[Value::Str(Arc::from(expected), None)]);
 }
 
 pub fn expect_float(script: &str, expected: f64) {