diff --git a/rust/src/gg.rs b/rust/src/gg.rs
index 2b39b1d..110e124 100644
--- a/rust/src/gg.rs
+++ b/rust/src/gg.rs
@@ -1,10 +1,39 @@
+use std::hash::Hash;
+use im_rc::{HashSet};
+
 pub mod lexer;
 
-use super::graph::Graph;
+#[derive(Clone, Eq, Hash, PartialEq)]
+pub struct OpenEdge(Value, Value); // edge, src
 
-#[derive(Clone, Eq, Hash, PartialEq, Debug)]
-pub enum Value<'a>{
-    Name(&'a str),
+#[derive(Clone, Eq, Hash, PartialEq)]
+pub enum Value{
+    Name(String),
     Number(i64),
-    Graph(&'a Graph<Value<'a>, Value<'a>>),
+    Tuple(Vec<OpenEdge>),
+    Graph(Graph),
+}
+
+#[derive(Clone, Eq, Hash, PartialEq)]
+struct Edge<V> {
+    dst_val: V,
+    src_val: V,
+}
+
+#[derive(Clone, Eq, Hash, PartialEq)]
+pub struct Graph {
+    edges: HashSet<(Value, OpenEdge)>, // dst, src
+}
+
+impl Graph {
+
+    pub fn new() -> Graph {
+        Graph{edges: HashSet::new()}
+    }
+
+    pub fn with(&self, dst_val: Value, src_edge: OpenEdge) -> Self {
+        Graph{
+            edges: self.edges.update((dst_val, src_edge)),
+        }
+    }
 }
diff --git a/rust/src/gg/gg.bnf b/rust/src/gg/gg.bnf
index c0e7760..3321945 100644
--- a/rust/src/gg/gg.bnf
+++ b/rust/src/gg/gg.bnf
@@ -1,19 +1,27 @@
+<name>         ::= <letter> | <name-tail>
+<name-charset> ::= <letter> | <number> | <mark>
+<name-tail>    ::= <name-chareset> <name-tail> | ""
+
+<number>      ::= "-" <ascii-number> <number-tail>
+                | <ascii-number> <number-tail>
+<number-tail> ::= <ascii-number> <number-tail> | ""
+
 <value> ::= <name> | <number> | <tuple> | <graph>
 
-<tuple>                      ::= "(" <tuple-open-edge>
-<tuple-open-edge>            ::= ")" | <tuple-open-edge-incomplete>
-<tuple-open-edge-incomplete> ::= <value> ")"
-                               | <value> "," <tuple-open-edge>
-                               | <value> "<" <tuple-open-edge-incomplete>
+<tuple>                 ::= "(" <tuple-edge>
+<tuple-edge>            ::= ")" | <tuple-edge-incomplete>
+<tuple-edge-incomplete> ::= <value> ")"
+                          | <value> "," <tuple-edge>
+                          | <value> "<" <tuple-edge-incomplete>
 
-<graph>                      ::= "{" <graph-branch>
-<graph-branch>               ::= "}" | <name> "<" <graph-open-edge-incomplete>
-<graph-open-edge-incomplete> ::= <value> "}"
-                               | <value> ";" <graph-branch>
-                               | <value> "<" <graph-open-edge-incomplete>
+<graph>                 ::= "{" <graph-branch>
+<graph-branch>          ::= "}" | <name> "<" <graph-edge-incomplete>
+<graph-edge-incomplete> ::= <value> "}"
+                          | <value> ";" <graph-branch>
+                          | <value> "<" <graph-edge-incomplete>
 
-<outer-graph>                      ::= <outer-graph-branch>
-<outer-graph-branch>               ::= <eof> | <name> "<" <outer-graph-open-edge-incomplete>
-<outer-graph-open-edge-incomplete> ::= <value> <eof>
-                                     | <value> ";" <outer-graph-branch>
-                                     | <value> "<" <outer-graph-open-edge-incomplete>
+<outer-graph>                 ::= <outer-graph-branch>
+<outer-graph-branch>          ::= <end> | <name> "<" <outer-graph-edge-incomplete>
+<outer-graph-edge-incomplete> ::= <value> <end>
+                                | <value> ";" <outer-graph-branch>
+                                | <value> "<" <outer-graph-edge-incomplete>
diff --git a/rust/src/gg/lexer.rs b/rust/src/gg/lexer.rs
index d6f7134..eb222d6 100644
--- a/rust/src/gg/lexer.rs
+++ b/rust/src/gg/lexer.rs
@@ -22,7 +22,7 @@ pub enum Error {
     IO(io::Error),
 }
 
-impl From<io::Error> for Error{
+impl From<io::Error> for Error {
     fn from(e: io::Error) -> Self {
         Error::IO(e)
     }
@@ -33,6 +33,7 @@ pub enum TokenKind {
     Name,
     Number,
     Punctuation,
+    End,
 }
 
 #[derive(Debug, PartialEq)]
@@ -105,7 +106,7 @@ impl<R: Read> Lexer<R>{
         &mut self,
         kind: TokenKind,
         pred: impl Fn(char) -> bool,
-    ) -> Result<Option<(Token, Location)>, Error> {
+    ) -> Result<(Token, Location), Error> {
 
         let loc = self.next_loc;
         self.buf.truncate(0);
@@ -115,8 +116,9 @@ impl<R: Read> Lexer<R>{
             let (c, ok) = self.peek_a_bool()?;
 
             if !ok || !pred(c) {
-                return Ok(Some(
-                    (Token{kind: kind, value: self.buf.clone()}, loc)
+                return Ok((
+                    Token{kind: kind, value: self.buf.clone()},
+                    loc
                 ))
             }
 
@@ -129,13 +131,16 @@ impl<R: Read> Lexer<R>{
         c == '-' || ('0' <= c && c <= '9')
     }
 
-    pub fn next(&mut self) -> Result<Option<(Token, Location)>, Error> {
+    pub fn next(&mut self) -> Result<(Token, Location), Error> {
 
         loop {
 
             let (c, ok) = self.peek_a_bool()?;
             if !ok {
-                return Ok(None);
+                return Ok((
+                    Token{kind: TokenKind::End, value: String::new()},
+                    self.next_loc,
+                ));
 
             } else if c == '*' {
                 self.discard_while(|c| c != '\n')?;
@@ -155,15 +160,16 @@ impl<R: Read> Lexer<R>{
                 let loc = self.next_loc;
                 self.discard();
 
-                return Ok(Some(
-                    (Token{kind: TokenKind::Punctuation, value: c.to_string()}, loc)
+                return Ok((
+                    Token{kind: TokenKind::Punctuation, value: c.to_string()},
+                    loc,
                 ))
 
             } else if c.is_ascii_whitespace() {
                 self.discard_while(|c| c.is_ascii_whitespace())?;
 
             } else {
-                return Err(Error::Tokenizing("unexpected character", self.next_loc));
+                return Err(Error::Tokenizing("invalid character", self.next_loc));
             }
         }
     }
@@ -192,26 +198,34 @@ mod tests {
         let tests = vec![
             Test{
                 input: "",
-                exp: vec![],
+                exp: vec![
+                    tok(TokenKind::End, "", 0, 0),
+                ],
             },
             Test{
                 input: "* foo",
-                exp: vec![],
+                exp: vec![
+                    tok(TokenKind::End, "", 0, 5),
+                ],
             },
             Test{
                 input: "* foo\n",
-                exp: vec![],
+                exp: vec![
+                    tok(TokenKind::End, "", 1, 0),
+                ],
             },
             Test{
                 input: "* foo\nbar",
                 exp: vec![
                     tok(TokenKind::Name, "bar", 1, 0),
+                    tok(TokenKind::End, "", 1, 3),
                 ],
             },
             Test{
                 input: "* foo\nbar ",
                 exp: vec![
                     tok(TokenKind::Name, "bar", 1, 0),
+                    tok(TokenKind::End, "", 1, 4),
                 ],
             },
             Test{
@@ -222,6 +236,7 @@ mod tests {
                     tok(TokenKind::Name, "f-o", 1, 0),
                     tok(TokenKind::Name, "f0O", 1, 4),
                     tok(TokenKind::Name, "Foo", 1, 8),
+                    tok(TokenKind::End, "", 1, 11),
                 ],
             },
             Test{
@@ -230,6 +245,7 @@ mod tests {
                     tok(TokenKind::Number, "1", 0, 0),
                     tok(TokenKind::Number, "100", 0, 2),
                     tok(TokenKind::Number, "-100", 0, 6),
+                    tok(TokenKind::End, "", 0, 10),
                 ],
             },
             Test{
@@ -242,6 +258,7 @@ mod tests {
                     tok(TokenKind::Number, "-3", 0, 4),
                     tok(TokenKind::Punctuation, "(", 0, 7),
                     tok(TokenKind::Punctuation, ")", 0, 8),
+                    tok(TokenKind::End, "", 0, 9),
                 ],
             },
         ];
@@ -253,9 +270,12 @@ mod tests {
             let mut res = Vec::new();
 
             loop {
-                if let Some(token) = l.next().expect("no errors expected") {
-                    res.push(token);
-                } else {
+                let (token, loc) = l.next().expect("no errors expected");
+                let is_end = token.kind == TokenKind::End;
+
+                res.push((token, loc));
+
+                if is_end {
                     break;
                 }
             }
diff --git a/rust/src/graph.rs b/rust/src/graph.rs
deleted file mode 100644
index eda2206..0000000
--- a/rust/src/graph.rs
+++ /dev/null
@@ -1,66 +0,0 @@
-use std::hash::Hash;
-use im_rc::{HashMap,HashSet};
-
-#[derive(Clone, Eq, Hash, PartialEq, Debug)]
-pub enum OpenEdgeSource<E, V>{
-    Value(V),
-    Tuple(Vec<OpenEdge<E, V>>),
-}
-
-#[derive(Clone, Eq, Hash, PartialEq, Debug)]
-pub struct OpenEdge<E, V>{
-    value: E,
-    source: OpenEdgeSource<E, V>,
-}
-
-#[derive(Clone, Eq, Hash, PartialEq, Debug)]
-pub struct Graph<E, V>
-where
-    E: Hash + Eq + Clone,
-    V: Hash + Eq + Clone,
-{
-    roots: HashMap<V, HashSet<OpenEdge<E, V>>>,
-}
-
-impl<E, V> Graph<E, V>
-where
-    E: Hash + Eq + Clone,
-    V: Hash + Eq + Clone,
-{
-
-    pub fn new() -> Graph<E, V> {
-        Graph{roots: HashMap::new()}
-    }
-
-    pub fn from_value(edge_value: E, source_value: V) -> OpenEdge<E, V> {
-        OpenEdge{
-            value: edge_value,
-            source: OpenEdgeSource::Value(source_value),
-        }
-    }
-
-    pub fn from_tuple(edge_value: E, source_tuple: Vec<OpenEdge<E, V>>) -> OpenEdge<E, V> {
-        OpenEdge{
-            value: edge_value,
-            source: OpenEdgeSource::Tuple(source_tuple),
-        }
-    }
-
-    pub fn with(&self, root_value: V, open_edge: OpenEdge<E, V>) -> Self {
-
-        let new_roots = self.roots.alter(
-            |set_option: Option<HashSet<OpenEdge<E, V>>>| -> Option<HashSet<OpenEdge<E, V>>> {
-                match set_option {
-                    None => Some(HashSet::unit(open_edge)),
-                    Some(set) => Some(set.update(open_edge)),
-                }
-            },
-            root_value,
-        );
-
-        Graph{
-            roots: new_roots,
-        }
-    }
-}
-
diff --git a/rust/src/lib.rs b/rust/src/lib.rs
index 975fba2..2e78910 100644
--- a/rust/src/lib.rs
+++ b/rust/src/lib.rs
@@ -1,2 +1 @@
-pub mod graph;
 pub mod gg;
diff --git a/rust/src/main.rs b/rust/src/main.rs
index b048f2a..f79c691 100644
--- a/rust/src/main.rs
+++ b/rust/src/main.rs
@@ -1,22 +1,2 @@
-use ginger::graph::Graph;
-
 fn main() {
-
-    let g = Graph::new().
-        with("foo", Graph::from_value(1, "bar"));
-
-    let g1 = g.
-        with("foo", Graph::from_value(1, "bar")).
-        with("foo", Graph::from_value(2, "baz"));
-
-    let g2 = g.
-        with("bar", Graph::from_tuple(100, vec![
-            Graph::from_value(20, "a"),
-            Graph::from_value(40, "b"),
-            Graph::from_value(60, "c"),
-        ]));
-
-    dbg!(g1 == g2);
-    dbg!(&g1);
-    dbg!(&g2);
 }