diff --git a/app/Parser.hs b/app/Parser.hs
new file mode 100644
index 0000000..3e981e8
--- /dev/null
+++ b/app/Parser.hs
@@ -0,0 +1,20 @@
+module Parser where
+
+import qualified Lexer
+
+type AST = Expr
+
+data Expr = Add Term Expr
+          | Sub Term Expr
+          | ETerm Term
+          deriving Show
+
+data Term = Mult Factor Term
+          | Div Factor Term
+          | TFactor Factor
+          deriving Show
+
+data Factor = Integer Int
+            | Parantheses Expr
+            | NegFactor Factor
+            deriving Show
diff --git a/simple-arithmetic-compiler.cabal b/simple-arithmetic-compiler.cabal
index 7ba5860..629dee5 100644
--- a/simple-arithmetic-compiler.cabal
+++ b/simple-arithmetic-compiler.cabal
@@ -52,7 +52,7 @@ executable simple-arithmetic-compiler
     main-is:          Main.hs
 
     -- Modules included in this executable, other than Main.
-    other-modules:    Lexer
+    other-modules:    Lexer, Parser
 
     -- LANGUAGE extensions used by modules in this package.
     -- other-extensions: