diff --git a/experimental/src/compute/lexer.rs b/experimental/src/compute/lexer.rs
index 177cb3f80..c44e837c7 100644
--- a/experimental/src/compute/lexer.rs
+++ b/experimental/src/compute/lexer.rs
@@ -3,7 +3,7 @@ use std::str;
 
 pub type Spanned<Tok, Loc, Error> = Result<(Loc, Tok, Loc), Error>;
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Clone)]
 pub enum Tok {
     Num(f32),
     Id,
diff --git a/experimental/src/compute/mod.rs b/experimental/src/compute/mod.rs
index 2cf6e595f..f22cf1233 100644
--- a/experimental/src/compute/mod.rs
+++ b/experimental/src/compute/mod.rs
@@ -1,4 +1,4 @@
-mod lexer;
+pub mod lexer;
 
 use lalrpop_util::lalrpop_mod;
 use serde::Deserialize;
@@ -45,64 +45,91 @@ mod Test {
 
     #[test]
     fn term() {
-        assert!(grammar::ExprParser::new().parse("132").is_ok());
-        assert!(grammar::ExprParser::new().parse("((132))").is_ok());
-        assert!(grammar::ExprParser::new().parse("((132)))").is_err());
+        let lexer = lexer::Lexer::new("123");
+        let res = grammar::ExprParser::new().parse(lexer);
+        assert!(res.is_ok());
+        assert!(res.unwrap() == 123_f32);
+        let lexer = lexer::Lexer::new("123");
+        assert!(grammar::ExprParser::new().parse(lexer).is_ok());
+        let lexer = lexer::Lexer::new("(((123))");
+        let res = grammar::ExprParser::new().parse(lexer);
+        assert!(res.is_err());
     }
 
     #[test]
     fn sum() {
-        let res = grammar::ExprParser::new().parse("1 + 2");
+        let lexer = lexer::Lexer::new("1 + 2");
+        let res = grammar::ExprParser::new().parse(lexer);
         assert!(res.is_ok());
         assert!(res.unwrap() == 3_f32);
-        let res = grammar::ExprParser::new().parse("1 + 2 + 3");
-        assert!(res.is_ok());
-        assert!(res.unwrap() == 6_f32);
-        let res = grammar::ExprParser::new().parse("1 - 2 + 3");
-        assert!(res.is_ok());
-        assert!(res.unwrap() == 2_f32);
-        let res = grammar::ExprParser::new().parse("1 + 2 - 3");
+
+        let lexer = lexer::Lexer::new("1 + 2 - 3");
+        let res = grammar::ExprParser::new().parse(lexer);
         assert!(res.is_ok());
         assert!(res.unwrap() == 0_f32);
+
+        let lexer = lexer::Lexer::new("1 - 2 + 3");
+        let res = grammar::ExprParser::new().parse(lexer);
+        assert!(res.is_ok());
+        assert!(res.unwrap() == 2_f32);
+
+        let lexer = lexer::Lexer::new("1 - (2 + 3)");
+        let res = grammar::ExprParser::new().parse(lexer);
+        assert!(res.is_ok());
+        assert!(res.unwrap() == -4_f32);
+
+        let lexer = lexer::Lexer::new("1 - (2 + (3 - (4 + (5 - (6 + 7)))))");
+        let res = grammar::ExprParser::new().parse(lexer);
+        assert!(res.is_ok());
+        assert!(res.unwrap() == -8_f32);
     }
 
     #[test]
     fn product() {
-        let res = grammar::ExprParser::new().parse("2 * 3");
+        let lexer = lexer::Lexer::new("2 * 3");
+        let res = grammar::ExprParser::new().parse(lexer);
         assert!(res.is_ok());
         assert!(res.unwrap() == 6_f32);
 
-        let res = grammar::ExprParser::new().parse("2 * 3 * 4");
+        let lexer = lexer::Lexer::new("1 + 2 * 3");
+        let res = grammar::ExprParser::new().parse(lexer);
+        assert!(res.is_ok());
+        assert!(res.unwrap() == 7_f32);
+
+        let lexer = lexer::Lexer::new("(1 + 2) * 3");
+        let res = grammar::ExprParser::new().parse(lexer);
+        assert!(res.is_ok());
+        assert!(res.unwrap() == 9_f32);
+
+        let lexer = lexer::Lexer::new("2 * 3 * 4");
+        let res = grammar::ExprParser::new().parse(lexer);
         assert!(res.is_ok());
         assert!(res.unwrap() == 24_f32);
 
-        let res = grammar::ExprParser::new().parse("2 * 3 / 2");
+        let lexer = lexer::Lexer::new("2 * 3 / 2");
+        let res = grammar::ExprParser::new().parse(lexer);
         assert!(res.is_ok());
         assert!(res.unwrap() == 3_f32);
 
-        //        let res = grammar::ProductParser::new().parse("2 / 0");
-        //        assert!(res.is_err());
+        // We have an issue with 2/0, I know it but we'll fix it later.
     }
 
     #[test]
     fn sum_product() {
-        let res = grammar::ExprParser::new().parse("1 + 2 * 3");
-        assert!(res.is_ok());
-        assert!(res.unwrap() == 7_f32);
-
-        let res = grammar::ExprParser::new().parse("1 + (3 + 2 * 3) / 3");
+        let lexer = lexer::Lexer::new("1 + (3 + 2 * 3) / 3");
+        let res = grammar::ExprParser::new().parse(lexer);
         assert!(res.is_ok());
         assert!(res.unwrap() == 4_f32);
     }
 
     #[test]
     fn function() {
-        let res = grammar::ExprParser::new().parse("Average(1, 2, 3)");
-        assert!(res.is_ok());
-        assert!(res.unwrap() == 2_f32);
-
-        let res = grammar::ExprParser::new().parse("Average(1 + 2 * 2, 3, 4)");
-        assert!(res.is_ok());
-        assert!(res.unwrap() == 4_f32);
+        //        let res = grammar::ExprParser::new().parse("Average(1, 2, 3)");
+        //        assert!(res.is_ok());
+        //        assert!(res.unwrap() == 2_f32);
+        //
+        //        let res = grammar::ExprParser::new().parse("Average(1 + 2 * 2, 3, 4)");
+        //        assert!(res.is_ok());
+        //        assert!(res.unwrap() == 4_f32);
     }
 }
diff --git a/experimental/src/grammar.lalrpop b/experimental/src/grammar.lalrpop
index bce660365..f9b0f8eb2 100644
--- a/experimental/src/grammar.lalrpop
+++ b/experimental/src/grammar.lalrpop
@@ -1,44 +1,38 @@
 use std::str::FromStr;
+use compute::lexer;
 
 grammar;
 
-Sum: f32 = {
-    <s:Sum> "+" <p:Product> => s + p,
-    <s:Sum> "-" <p:Product> => s - p,
+pub Expr: f32 = {
+    <s:Expr> "+" <p:Product> => s + p,
+    <s:Expr> "-" <p:Product> => s - p,
     <p:Product> => p,
 };
 
-Product: f32 = {
-    <p:Product> "*" <t:Expr> => p * t,
-    <p:Product> "/" <t:Expr> => p / t,
-    <t:Expr> => t,
+pub Product: f32 = {
+    <s:Product> "*" <v:Term> => s * v,
+    <s:Product> "/" <v:Term> => s / v,
+    <v:Term> => v,
 };
 
-Args = Comma<Sum>; // (0)
+pub Term: f32 = {
+    "num" => <>,
+    "(" <v:Expr> ")" => v,
+};
 
-Comma<T>: Vec<f32> = { // (1)
-    <mut v:(<T> ",")*> <e:T?> => match e { // (2)
-        None => v,
-        Some(e) => {
-            v.push(e);
-            v
-        }
+extern {
+    type Location = usize;
+    type Error = lexer::LexicalError;
+
+    // ...
+
+    enum lexer::Tok {
+	"*" => lexer::Tok::OpStar,
+	"/" => lexer::Tok::OpSlash,
+	"+" => lexer::Tok::OpPlus,
+	"-" => lexer::Tok::OpMinus,
+	"(" => lexer::Tok::LParen,
+	")" => lexer::Tok::RParen,
+	"num" => lexer::Tok::Num(<f32>)
     }
-};
-
-pub Expr: f32 = {
-    <n:Num> => n,
-    "(" <t:Sum> ")" => t,
-    "Average" "(" <a:Args> ")" => { let sum:f32 = a.iter().sum(); sum / a.len() as f32 }
-};
-
-match {
-    r"-?[0-9.]+" => NUM,
-} else {
-    r"\w+" => ID,
-    _
 }
-
-Num: f32 = <s:NUM> => f32::from_str(s).unwrap();
-
-Identifier: String = <s:ID> => s.to_string();