Changing history behavior to save duplicate lines

Adding currently-inactive parameter to configure max length of history

repl/src/config_params.rs

@@ -16,6 +16,7 @@ pub const CFG_STRING_STYLE: &str = "ReplStringStyle";
 pub const CFG_ERROR_STYLE: &str = "ReplErrorStyle";
 pub const CFG_BRACKET_MATCH_STYLE: &str = "ReplBracketMatchStyle";
 pub const CFG_BRACKET_MATCH_ENABLED: &str = "ReplBracketMatchEnabled";
+pub const CFG_HISTORY_MAX_LEN: &str = "ReplHistoryMaxLen";
 
 #[derive(Default, Debug)]
 pub struct ReplParams {

repl/src/main.rs

@@ -113,10 +113,13 @@ fn start_interactive_mode(repl_params: Shared<ReplParams>, mut metta: MettaShim)
 
     //Run the repl init file
     metta.load_metta_module(repl_params.borrow().repl_config_metta_path.clone());
+    let max_len = metta.get_config_int(CFG_HISTORY_MAX_LEN).unwrap_or_else(|| 500);
 
     //Init RustyLine
     let config = Config::builder()
         .history_ignore_space(true)
+        .max_history_size(max_len as usize).unwrap()
+        .history_ignore_dups(false).unwrap()
         .completion_type(CompletionType::List)
         .edit_mode(EditMode::Emacs)
         .build();

repl/src/metta_shim.rs

@@ -194,6 +194,9 @@ impl MettaShim {
         result
     }
 
+    pub fn get_config_int(&mut self, _config_name: &str) -> Option<isize> {
+        None //TODO.  Make this work when I have reliable value atom bridging
+    }
 }
 
 #[cfg(not(feature = "python"))]

repl/src/repl.default.metta

@@ -1,4 +1,6 @@
 
+; !(pragma! ReplHistoryMaxLen 500) ; TODO: enable this when I have value bridging implemented.
+
 !(pragma! ReplDefaultPrompt "> ")
 ; !(pragma! ReplStyledPrompt "\x1b[1;32m> \x1b[0m") ; TODO: currently the MeTTa string parser doesn't resolve escape chars, although perhaps it should