Project start: writing step step0_repl

Step 0 alone only act as an echo for the input, define the sructure of
the interpreter

Signed-off-by: teo3300 <matteo.rogora@live.it>

src/main.rs

@@ -0,0 +1,19 @@
+// io lib to read input and print output
+use std::io::{self, Write};
+
+mod step0_repl;
+use step0_repl::rep;
+
+fn main() -> io::Result<()> {
+    loop {
+        print!("user> ");
+        // Flush the prompt to appear before command
+        let _ = io::stdout().flush();
+
+        let mut input = String::new();
+
+        io::stdin().read_line(&mut input)?;
+
+        print!("{}", rep(&input));
+    }
+}