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);
+}

src/expr.rs

@@ -35,12 +35,12 @@ impl fmt::Display for Expr {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             // PRIMITIVES
-            Int(num) => write!(f, "{} : Int", *num),
+            Int(num) => write!(f, "{}", *num),
             Frac(numerator, denominator) => {
                 if *denominator == 10 {
-                    write!(f, "{} : Frac", (*numerator as f64 / 10.0))
+                    write!(f, "{}", (*numerator as f64 / 10.0))
                 } else {
-                    write!(f, "{}/{} : Frac", numerator, denominator)
+                    write!(f, "{}/{}", numerator, denominator)
                 }
             },
             Str(string) => {
@@ -52,12 +52,26 @@ impl fmt::Display for Expr {
                         .replace("\n", "\\n")
                         .replace("\r", "\\r");
 
-                write!(f, "\"{}\" : String", escaped_str)
+                write!(f, "\"{}\"", escaped_str)
             },
-            Char(ch) => write!(f, "'{}' : Char", *ch),
-            Bool(true) => write!(f, "True : Bool"),
-            Bool(false) => write!(f, "False : Bool"),
+            Char(ch) => write!(f, "'{}'", *ch),
+            Bool(true) => write!(f, "True"),
+            Bool(false) => write!(f, "False"),
             Closure(args, _) => write!(f, "<{}-argument function>", args.len()),
+            ApplyVariant(name, opt_exprs) => {
+                match opt_exprs {
+                    None => write!(f, "{}", name),
+                    Some(exprs) => {
+                        let contents =
+                            exprs.into_iter()
+                                .map(|expr| format!(" {}", expr))
+                                .collect::<Vec<_>>()
+                                .join(",");
+
+                        write!(f, "{}{}", name, contents)
+                    }
+                }
+            },
 
             // ERRORS
             Error(Problem::UnrecognizedVarName(name)) => write!(f, "NAMING ERROR: Unrecognized var name `{}`", name),