Get rid of old evaluator file

No longer need it

src/evaluator.rs

@@ -1,104 +0,0 @@
-/*
-use parser::AST;
-
-struct Evaluator {
-    ast: AST
-}
-
-pub type EvaluatorResult<T> = Result<T, EvaluatorError>;
-
-struct EvaluatorError {
-    err: String
-}
-
-impl Evaluator {
-    pub fn run(self) -> String {
-        match reduce_full(self.ast) {
-            Err(e) => format!("{}", e.err),
-            Ok(ast) => format!("{}", ast)
-        }
-    }
-}
-
-impl AST {
-    fn can_reduce(&self) -> bool {
-        use parser::AST::*;
-        match self {
-            &Number(_) => false,
-            &Name(_) => false,
-            _ => true
-        }
-    }
-}
-
-fn reduce_full(ast: AST) -> EvaluatorResult<AST> {
-    let mut ast = ast;
-    while ast.can_reduce() {
-        ast = try!(reduce_step(ast));
-    }
-
-    Ok(ast)
-}
-
-fn reduce_step(ast: AST) -> EvaluatorResult<AST> {
-    use parser::AST::*;
-    match ast {
-        Definition(name, value) => {
-            Ok(*value)
-        },
-        Block(mut block_nodes) => {
-            match block_nodes.pop() {
-                None => Err(EvaluatorError { err: format!("Block with no statements") }),
-                Some(node) => reduce_full(node),
-            }
-        },
-        BinOp(left, op, right) => {
-            let left = try!(reduce_full(*left));
-            let op = try!(reduce_full(*op));
-            let right = try!(reduce_full(*right));
-            match (left, op, right) {
-                (Number(l), Name(op), Number(r)) => {
-                    match &op[..] {
-                        "+" => Ok(Number(l + r)),
-                        "-" => Ok(Number(l - r)),
-                        "*" => Ok(Number(l * r)),
-                        "/" => {
-                            if r == 0.0 {
-                                Err(EvaluatorError { err: format!("Divide by zero") })
-                            } else {
-                                Ok(Number(l / r))
-                            }
-                        },
-                        _ => Err(EvaluatorError { err: format!("Bad BinOp operator") })
-                    }
-                },
-                _ => Err(EvaluatorError { 
-                    err: format!("Bad arguments for BinOp")
-                })
-            }
-        },
-        Number(_) => Ok(ast),
-        Name(_) => Ok(ast),
-
-    }
-}
-
-pub fn evaluate(ast: AST) -> String {
-    let ev = Evaluator { ast: ast };
-    ev.run()
-}
-
-#[cfg(test)]
-mod tests {
-    use tokenizer::tokenize;
-    use parser::{parse, AST};
-    use super::evaluate;
-
-    #[test]
-    fn test_basic_evaluation() {
-        let input = "1 + 2\n";
-        let output = evaluate(parse(tokenize(input)).unwrap());
-        assert_eq!(output, "3");
-    }
-}
-*/