Less memory allocations at runtime

tests/forth/definitions.rs

@@ -128,7 +128,7 @@ fn forget_removes_word() {
     let stack = f.stack();
     assert_eq!(stack.len(), 1);
     match &stack[0] {
-        Value::Str(s, _) => assert_eq!(s, "double"),
+        Value::Str(s, _) => assert_eq!(s.as_ref(), "double"),
         other => panic!("expected Str, got {:?}", other),
     }
 }

tests/forth/errors.rs

@@ -46,7 +46,7 @@ fn float_literal() {
 fn string_with_spaces() {
     let f = run(r#""hello world" !x @x"#);
     match stack_top(&f) {
-        cagire::forth::Value::Str(s, _) => assert_eq!(s, "hello world"),
+        cagire::forth::Value::Str(s, _) => assert_eq!(s.as_ref(), "hello world"),
         other => panic!("expected string, got {:?}", other),
     }
 }

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) {