Hardcode Read and Echo

cli/src/main.rs

@@ -2,8 +2,12 @@ extern crate roc;
 
 use std::fs::File;
 use std::io::prelude::*;
+use roc::expr::Expr::*;
+use roc::expr::Expr;
 use roc::eval::eval;
+use roc::eval::from_evaluated;
 use roc::parse;
+use std::io;
 
 fn main() -> std::io::Result<()> {
     let mut file = File::open("test.roc")?;
@@ -13,7 +17,34 @@ fn main() -> std::io::Result<()> {
 
     let expr = parse::parse_string(contents.as_str()).unwrap();
 
-    println!("\n\u{001B}[4mroc out\u{001B}[24m\n\n{}\n", eval(expr).to_string());
+    match from_evaluated(eval(expr)) {
+        Error(problem) => {
+            println!("\n\u{001B}[4mruntime error\u{001B}[24m\n\n{:?}\n", problem)
+        },
+        ApplyVariant(name, payload) => {
+            match name.as_str() {
+                "Echo" => {
+                    println!("{}", payload.unwrap().first().unwrap());
+                },
+                "Read" => {
+                    let mut input = String::new();
+                    io::stdin().read_line(&mut input)?;
+
+                    println!("[debug] You said: {}", input);
+                },
+                _ => {
+                    display_expr(ApplyVariant(name, payload));
+                }
+            }
+        },
+        output => {
+            display_expr(output);
+        }
+    };
 
     Ok(())
 }
+
+fn display_expr(expr: Expr) {
+    println!("\n\u{001B}[4mroc out\u{001B}[24m\n\n{}\n", expr);
+}