First pass at evaluation

Very incomplete

src/evaluate.rs

@@ -0,0 +1,25 @@
+use parser::AST;
+use parser::AST::*;
+
+pub fn evaluate(ast: AST) -> String {
+    match reduce(ast) {
+        None => return "error".to_string(),
+        Some(DoNothing) => "".to_string(),
+        Some(Number(n)) => return format!("{}", n),
+        Some(LangString(s)) => return format!("\"{}\"", s),
+        _ => return "not implemented".to_string()
+    }
+}
+
+fn reduce(ast: AST) -> Option<AST> {
+    match ast {
+        Statements(stmts) => {
+            let mut reduction = Some(DoNothing);
+            for stmt in stmts.into_iter() {
+                reduction = reduce(stmt);
+            }
+            reduction
+        },
+        other_ast => Some(other_ast)
+    }
+}

src/main.rs

@@ -5,9 +5,11 @@ use std::process;
 
 use tokenizer::tokenize;
 use parser::{parse, ParseResult};
+use evaluate::evaluate;
 
 mod tokenizer;
 mod parser;
+mod evaluate;
 
 
 fn main() {
@@ -39,14 +41,13 @@ fn repl() {
                 println!("Tokens: {:?}", tokens);
 
                 match parse(tokens) {
-                    ParseResult::Ok(ast) => println!("AST: {:?}", ast),
+                    ParseResult::Ok(ast) => {
+                        println!("AST: {:?}", ast);
+                        let eval = evaluate(ast);
+                        println!("{}", eval);
+                    },
                     ParseResult::Err(err) => println!("Error: {}", err)
                 }
-
-                /*
-                let eval = evaluate(&ast);
-                println!("{}", eval);
-                */
             },
             Err(err) => {
                 println!("Error: {}", err);

src/parser.rs

@@ -13,7 +13,8 @@ pub enum AST {
     Binding(String, Box<AST>),
     Statements(Vec<AST>),
     IfStatement(Box<AST>, Box<AST>, Option<Box<AST>>),
-    WhileStatement(Box<AST>, Box<AST>)
+    WhileStatement(Box<AST>, Box<AST>),
+    DoNothing
 }
 
 pub enum ParseResult {