Use dialoguer for prompts with history.

Modify intro and help text.

interpreter/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "leo-interpreter"
-version = "2.3.0"
+version = "2.3.1"
 authors = [ "The Leo Team <[email protected]>" ]
 description = "Interpreter for the Leo programming language"
 homepage = "https://leo-lang.org"
@@ -48,6 +48,10 @@ workspace = true
 [dependencies.indexmap]
 workspace = true
 
+[dependencies.dialoguer]
+version = "0.11.0"
+features = [ "history" ]
+
 [dependencies.rand]
 workspace = true
 

interpreter/src/lib.rs

@@ -242,7 +242,11 @@ impl Interpreter {
                     });
                 };
 
-                if matches!(act, LeoInterpretOver(..)) { self.cursor.over()? } else { self.cursor.step()? }
+                if matches!(act, LeoInterpretOver(..)) {
+                    self.cursor.over()?
+                } else {
+                    StepResult { finished: false, value: None }
+                }
             }
 
             Step => self.cursor.whole_step()?,
@@ -390,8 +394,10 @@ impl Interpreter {
     }
 }
 
-const INSTRUCTIONS: &str = "
-This is the Leo Interpreter. You probably want to start by running a function or transition.
+const INTRO: &str = "This is the Leo Interpreter. Try the command `#help`.";
+
+const HELP: &str = "
+You probably want to start by running a function or transition.
 For instance
 #into program.aleo/main()
 Once a function is running, commands include
@@ -409,12 +415,19 @@ When executing Aleo VM code, you can print the value of a register like this:
 
 You may also use one letter abbreviations for these commands, such as #i.
 
-You may simply enter expressions or statements on the command line
+Note that this interpreter is not line oriented as in many common debuggers;
+rather it is oriented around expressions and statements.
+As you step into code, individual expressions or statements will
+be evaluated one by one, including arguments of function calls.
+
+You may simply enter Leo expressions or statements on the command line
 to evaluate. For instance, if you want to see the value of a variable w:
 w
 If you want to set w to a new value:
 w = z + 2u8;
 
+Note that statements (like the assignment above) must end with a semicolon.
+
 If there are futures available to be executed, they will be listed by
 numerical index, and you may run them using `#future` (or `#f`); for instance
 #future 0
@@ -530,10 +543,10 @@ pub fn interpret(
     block_height: u32,
 ) -> Result<()> {
     let mut interpreter = Interpreter::new(leo_filenames.iter(), aleo_filenames.iter(), signer, block_height)?;
-    let mut buffer = String::new();
-    println!("{}", INSTRUCTIONS);
+    println!("{}", INTRO);
+
+    let mut history = dialoguer::BasicHistory::new();
     loop {
-        buffer.clear();
         if let Some(v) = interpreter.view_current_in_context() {
             println!("{v}");
         } else if let Some(v) = interpreter.view_current() {
@@ -542,9 +555,16 @@ pub fn interpret(
         for (i, future) in interpreter.cursor.futures.iter().enumerate() {
             println!("{i}: {future}");
         }
-        std::io::stdin().read_line(&mut buffer).expect("read_line");
-        let action = match buffer.trim() {
+
+        let user_input: String =
+            dialoguer::Input::new().with_prompt("Command?").history_with(&mut history).interact_text().unwrap();
+
+        let action = match user_input.trim() {
             "" => continue,
+            "#h" | "#help" => {
+                println!("{}", HELP);
+                continue;
+            }
             "#i" | "#into" => InterpreterAction::Into,
             "#s" | "#step" => InterpreterAction::Step,
             "#o" | "#over" => InterpreterAction::Over,