diff --git a/src/lib.rs b/src/lib.rs
index 7a0fb80..89ed7e9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,93 +1,10 @@
 #![feature(assert_matches)]
 #![allow(dead_code)] //TODO eventually turn this off
 mod bnf;
+mod parser;
 mod sequence;
 
-use bnf::Bnf;
-use std::rc::Rc;
-
-pub type ParseResult<I, O, E> = Result<(O, I), E>;
-
-pub trait Parser<I, O, E> {
-    fn parse(&self, input: I) -> ParseResult<I, O, E>;
-    fn bnf(&self) -> Option<Bnf> {
-        None
-    }
-
-    fn map<'a, F, O2>(self, map_fn: F) -> BoxedParser<'a, I, O2, E>
-    where
-        Self: Sized + 'a,
-        I: 'a,
-        E: 'a,
-        O: 'a,
-        O2: 'a,
-        F: Fn(O) -> O2 + 'a,
-    {
-        BoxedParser::new(map(self, map_fn))
-    }
-
-    fn to<'a, O2>(self, item: O2) -> BoxedParser<'a, I, O2, E>
-    where
-        Self: Sized + 'a,
-        I: 'a,
-        O: 'a,
-        O2: Clone + 'a,
-        E: 'a,
-    {
-        self.map(move |_| item.clone())
-    }
-
-    fn then<'a, P, O2>(self, next_parser: P) -> BoxedParser<'a, I, (O, O2), E>
-    where
-        Self: Sized + 'a,
-        I: 'a,
-        O: 'a,
-        O2: 'a,
-        E: 'a,
-        P: Parser<I, O2, E> + 'a,
-    {
-        BoxedParser::new(sequence::tuple2(self, next_parser))
-    }
-}
-
-pub struct BoxedParser<'a, I, O, E> {
-    inner: Box<dyn Parser<I, O, E> + 'a>,
-}
-
-impl<'a, I, O, E> BoxedParser<'a, I, O, E> {
-    fn new<P>(inner: P) -> Self
-    where
-        P: Parser<I, O, E> + 'a,
-    {
-        BoxedParser {
-            inner: Box::new(inner),
-        }
-    }
-}
-
-impl<'a, I, O, E> Parser<I, O, E> for BoxedParser<'a, I, O, E> {
-    fn parse(&self, input: I) -> ParseResult<I, O, E> {
-        self.inner.parse(input)
-    }
-}
-
-impl<I, O, E, F> Parser<I, O, E> for F
-where
-    F: Fn(I) -> ParseResult<I, O, E>,
-{
-    fn parse(&self, input: I) -> ParseResult<I, O, E> {
-        self(input)
-    }
-}
-
-impl<I, O, E, T> Parser<I, O, E> for Rc<T>
-where
-    T: Parser<I, O, E>,
-{
-    fn parse(&self, input: I) -> ParseResult<I, O, E> {
-        self.as_ref().parse(input)
-    }
-}
+use parser::{ParseResult, Parser};
 
 fn literal(expected: &'static str) -> impl Fn(&str) -> ParseResult<&str, &str, &str> {
     move |input| match input.get(0..expected.len()) {
diff --git a/src/parser.rs b/src/parser.rs
new file mode 100644
index 0000000..87d0bad
--- /dev/null
+++ b/src/parser.rs
@@ -0,0 +1,85 @@
+use crate::bnf::Bnf;
+use std::rc::Rc;
+
+pub type ParseResult<I, O, E> = Result<(O, I), E>;
+
+pub trait Parser<I, O, E> {
+    fn parse(&self, input: I) -> ParseResult<I, O, E>;
+    fn bnf(&self) -> Option<Bnf> {
+        None
+    }
+
+    fn map<'a, F, O2>(self, map_fn: F) -> BoxedParser<'a, I, O2, E>
+    where
+        Self: Sized + 'a,
+        I: 'a,
+        E: 'a,
+        O: 'a,
+        O2: 'a,
+        F: Fn(O) -> O2 + 'a,
+    {
+        BoxedParser::new(crate::map(self, map_fn))
+    }
+
+    fn to<'a, O2>(self, item: O2) -> BoxedParser<'a, I, O2, E>
+    where
+        Self: Sized + 'a,
+        I: 'a,
+        O: 'a,
+        O2: Clone + 'a,
+        E: 'a,
+    {
+        self.map(move |_| item.clone())
+    }
+
+    fn then<'a, P, O2>(self, next_parser: P) -> BoxedParser<'a, I, (O, O2), E>
+    where
+        Self: Sized + 'a,
+        I: 'a,
+        O: 'a,
+        O2: 'a,
+        E: 'a,
+        P: Parser<I, O2, E> + 'a,
+    {
+        BoxedParser::new(crate::sequence::tuple2(self, next_parser))
+    }
+}
+
+pub struct BoxedParser<'a, I, O, E> {
+    inner: Box<dyn Parser<I, O, E> + 'a>,
+}
+
+impl<'a, I, O, E> BoxedParser<'a, I, O, E> {
+    fn new<P>(inner: P) -> Self
+    where
+        P: Parser<I, O, E> + 'a,
+    {
+        BoxedParser {
+            inner: Box::new(inner),
+        }
+    }
+}
+
+impl<'a, I, O, E> Parser<I, O, E> for BoxedParser<'a, I, O, E> {
+    fn parse(&self, input: I) -> ParseResult<I, O, E> {
+        self.inner.parse(input)
+    }
+}
+
+impl<I, O, E, F> Parser<I, O, E> for F
+where
+    F: Fn(I) -> ParseResult<I, O, E>,
+{
+    fn parse(&self, input: I) -> ParseResult<I, O, E> {
+        self(input)
+    }
+}
+
+impl<I, O, E, T> Parser<I, O, E> for Rc<T>
+where
+    T: Parser<I, O, E>,
+{
+    fn parse(&self, input: I) -> ParseResult<I, O, E> {
+        self.as_ref().parse(input)
+    }
+}