begin working on command implementation for REPL

src/info/repl/command.rs

@@ -112,13 +112,15 @@ pub enum Value
     String(String),
     Symbol(String),
     List(Vec<Value>),
-    
-    Command(Box<dyn Command>),
 }
 
+/// Trait for commands.
+///
+/// # Defining commands
+/// A command object should be created once only, and then referenced and executed using `params` and through mutating `cx`.
 pub trait Command: fmt::Debug
 {
-    fn execute(self: Box<Self>, cx: &mut Context<'_>, params: Vec<Value>) -> eyre::Result<()>;
+    fn execute(&self, cx: &mut Context<'_>, params: Vec<Value>) -> eyre::Result<()>;
 }
 
 /// Command structurally parsed.