diff --git a/src/main.rs b/src/main.rs
index ebebce3..2374721 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,10 +1,10 @@
 use std::fmt::Write;
-pub mod parser;
 pub mod compiler;
+pub mod parser;
 
 fn main() {
     let mut ops: Vec<(Option<String>, Vec<String>)> = Vec::new();
-    
+
     //    OpMemoryModel Logical GLSL450
     //    OpEntryPoint Fragment %main "main"
     //    OpExecutionMode %main OriginUpperLeft
@@ -18,23 +18,88 @@ fn main() {
     //%5 = OpLabel
     //    OpReturn
     //    OpFunctionEnd
-    
+
     ops.push((None, vec!["OpCapability".to_string(), "Shader".to_string()]));
-    ops.push((Some("%1".to_string()), vec!["OpExtInstImport".to_string(), "\"GLSL.std.450\"".to_string()]));
-    ops.push((None, vec!["OpMemoryModel".to_string(), "Logical".to_string(), "GLSL450".to_string()]));
-    ops.push((None, vec!["OpEntryPoint".to_string(), "Fragment".to_string(), "%main".to_string(), "\"main\"".to_string()]));
-    ops.push((None, vec!["OpExecutionMode".to_string(), "%main".to_string(), "OriginUpperLeft".to_string()]));
-    ops.push((None, vec!["OpSource".to_string(), "GLSL".to_string(), "450".to_string()]));
-    ops.push((None, vec!["OpSourceExtension".to_string(), "\"GL_GOOGLE_cpp_style_line_directive\"".to_string()]));
-    ops.push((None, vec!["OpSourceExtension".to_string(), "\"GL_GOOGLE_include_directive\"".to_string()]));
-    ops.push((None, vec!["OpName".to_string(), "%main".to_string(), "\"main\"".to_string()]));
+    ops.push((
+        Some("%1".to_string()),
+        vec![
+            "OpExtInstImport".to_string(),
+            "\"GLSL.std.450\"".to_string(),
+        ],
+    ));
+    ops.push((
+        None,
+        vec![
+            "OpMemoryModel".to_string(),
+            "Logical".to_string(),
+            "GLSL450".to_string(),
+        ],
+    ));
+    ops.push((
+        None,
+        vec![
+            "OpEntryPoint".to_string(),
+            "Fragment".to_string(),
+            "%main".to_string(),
+            "\"main\"".to_string(),
+        ],
+    ));
+    ops.push((
+        None,
+        vec![
+            "OpExecutionMode".to_string(),
+            "%main".to_string(),
+            "OriginUpperLeft".to_string(),
+        ],
+    ));
+    ops.push((
+        None,
+        vec![
+            "OpSource".to_string(),
+            "GLSL".to_string(),
+            "450".to_string(),
+        ],
+    ));
+    ops.push((
+        None,
+        vec![
+            "OpSourceExtension".to_string(),
+            "\"GL_GOOGLE_cpp_style_line_directive\"".to_string(),
+        ],
+    ));
+    ops.push((
+        None,
+        vec![
+            "OpSourceExtension".to_string(),
+            "\"GL_GOOGLE_include_directive\"".to_string(),
+        ],
+    ));
+    ops.push((
+        None,
+        vec![
+            "OpName".to_string(),
+            "%main".to_string(),
+            "\"main\"".to_string(),
+        ],
+    ));
     ops.push((Some("%void".to_string()), vec!["OpTypeVoid".to_string()]));
-    ops.push((Some("%3".to_string()), vec!["OpTypeFunction".to_string(), "%void".to_string()]));
-    ops.push((Some("%main".to_string()), vec!["OpFunction".to_string(), "%void".to_string(), "None".to_string(), "%3".to_string()]));
+    ops.push((
+        Some("%3".to_string()),
+        vec!["OpTypeFunction".to_string(), "%void".to_string()],
+    ));
+    ops.push((
+        Some("%main".to_string()),
+        vec![
+            "OpFunction".to_string(),
+            "%void".to_string(),
+            "None".to_string(),
+            "%3".to_string(),
+        ],
+    ));
     ops.push((Some("%5".to_string()), vec!["OpLabel".to_string()]));
     ops.push((None, vec!["OpReturn".to_string()]));
     ops.push((None, vec!["OpFunctionEnd".to_string()]));
-    
+
     let mut out: String = String::new();
 
     for op in ops {
diff --git a/src/parser/mod.rs b/src/parser/mod.rs
index c56d16f..427f1f6 100644
--- a/src/parser/mod.rs
+++ b/src/parser/mod.rs
@@ -2,9 +2,94 @@
 mod tests;
 
 use std::iter::Peekable;
+use std::ops::RangeInclusive;
 use std::vec::IntoIter;
 
-#[derive(Debug, PartialEq)]
+#[derive(Clone, Debug)]
+enum Location {
+    Char {
+        line: usize,
+        col: usize,
+    },
+    String {
+        lines: RangeInclusive<usize>,
+        cols: RangeInclusive<usize>,
+    },
+}
+
+#[derive(Debug)]
+pub enum ParseError {
+    UnexpectedParenClose(Location),
+    UnexpectedEof,
+}
+
+impl Location {
+    /// Since [`Localised`] doesn't test for location match, allow for creating simple dummy
+    /// locations for testing
+    #[cfg(test)]
+    pub fn dummy() -> Location {
+        Self::Char { line: 0, col: 0 }
+    }
+
+    pub fn range(start: &Location, end: &Location) -> Location {
+        Location::String {
+            lines: start.line_start()..=end.line_end(),
+            cols: start.col_start()..=end.col_end(),
+        }
+    }
+
+    pub fn line_start(&self) -> usize {
+        match self {
+            Location::Char { line, .. } => *line,
+            Location::String { lines, .. } => *lines.start(),
+        }
+    }
+
+    pub fn col_start(&self) -> usize {
+        match self {
+            Location::Char { col, .. } => *col,
+            Location::String { cols, .. } => *cols.start(),
+        }
+    }
+
+    pub fn line_end(&self) -> usize {
+        match self {
+            Location::Char { line, .. } => *line,
+            Location::String { lines, .. } => *lines.end(),
+        }
+    }
+
+    pub fn col_end(&self) -> usize {
+        match self {
+            Location::Char { col, .. } => *col,
+            Location::String { cols, .. } => *cols.end(),
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+struct Localised<T: Clone> {
+    location: Location,
+    item: T,
+}
+
+impl<T: Clone> Localised<T> {
+    #[cfg(test)]
+    pub fn dummy_location(item: T) -> Self {
+        Self {
+            location: Location::dummy(),
+            item,
+        }
+    }
+}
+
+impl<T: PartialEq + Clone> PartialEq for Localised<T> {
+    fn eq(&self, other: &Self) -> bool {
+        self.item.eq(&other.item)
+    }
+}
+
+#[derive(Debug, PartialEq, Clone)]
 pub enum Token {
     LeftParen,
     RightParen,
@@ -13,56 +98,109 @@ pub enum Token {
 
 #[derive(Debug, PartialEq, Clone)]
 pub enum Ast {
-    Symbol(String),
-    List(Vec<Ast>),
+    Symbol(Localised<String>),
+    List(Localised<Vec<Ast>>),
     Root(Vec<Ast>),
 }
 
-pub fn tokenize(input: &str) -> Vec<Token> {
+pub fn tokenize(input: &str) -> Vec<Localised<Token>> {
     let mut tokens = Vec::new();
-    let mut chars = input.chars().peekable();
-    while let Some(c) = chars.next() {
+    // let mut chars = input.chars().peekable();
+    let mut chars = (1..)
+        .zip(input.split('\n'))
+        .flat_map(|(l_num, l)| {
+            (1..).zip(l.chars()).map(move |(c_num, c)| Localised {
+                location: Location::Char {
+                    line: l_num,
+                    col: c_num,
+                },
+                item: c,
+            })
+        })
+        .peekable();
+    while let Some(Localised { location, item: c }) = chars.next() {
         match c {
-            '(' => tokens.push(Token::LeftParen),
-            ')' => tokens.push(Token::RightParen),
+            '(' => tokens.push(Localised {
+                location,
+                item: Token::LeftParen,
+            }),
+            ')' => tokens.push(Localised {
+                location,
+                item: Token::RightParen,
+            }),
             _ if c.is_whitespace() => (),
             _ => {
+                let start = location.clone();
+                let mut end = location;
                 let mut symbol = c.to_string();
-                while let Some(&c) = chars.peek() {
-                    if c.is_whitespace() || c == '(' || c == ')' {
+                while let Some(Localised { item: c, .. }) = chars.peek() {
+                    if c.is_whitespace() || *c == '(' || *c == ')' {
                         break;
                     }
-                    symbol.push(c);
-                    chars.next();
+                    symbol.push(*c);
+                    let Localised { location, .. } = chars.next().unwrap();
+                    end = location;
                 }
-                tokens.push(Token::Symbol(symbol));
+                tokens.push(Localised {
+                    location: Location::range(&start, &end),
+                    item: Token::Symbol(symbol),
+                });
             }
         }
     }
     tokens
 }
 
-fn parse_expr(tokens: &mut Peekable<IntoIter<Token>>) -> Ast {
+fn parse_expr(tokens: &mut Peekable<IntoIter<Localised<Token>>>) -> Result<Ast, ParseError> {
     match tokens.next() {
-        Some(Token::LeftParen) => {
+        Some(Localised {
+            location: start,
+            item: Token::LeftParen,
+        }) => {
             let mut list = Vec::new();
-            while tokens.peek() != Some(&Token::RightParen) {
-                list.push(parse_expr(tokens));
+            while !matches!(
+                tokens.peek(),
+                Some(Localised {
+                    item: Token::RightParen,
+                    ..
+                })
+            ) {
+                list.push(parse_expr(tokens)?);
             }
-            tokens.next();
-            Ast::List(list)
+            let Some(Localised {
+                location: end,
+                item: Token::RightParen,
+            }) = tokens.next()
+            else {
+                unreachable!()
+            };
+            Ok(Ast::List(Localised {
+                location: Location::range(&start, &end),
+                item: list,
+            }))
         }
-        Some(Token::RightParen) => panic!("unexpected )"),
-        Some(Token::Symbol(s)) => Ast::Symbol(s),
-        None => panic!("unexpected EOF"),
+        Some(Localised {
+            location,
+            item: Token::RightParen,
+        }) => Err(ParseError::UnexpectedParenClose(location)),
+        Some(Localised {
+            location,
+            item: Token::Symbol(s),
+        }) => Ok(Ast::Symbol(Localised { location, item: s })),
+        None => Err(ParseError::UnexpectedEof),
     }
 }
 
-pub fn parse(tokens: Vec<Token>) -> Ast {
+pub fn parse(tokens: Vec<Localised<Token>>) -> Result<Ast, ParseError> {
     let mut tokens = tokens.into_iter().peekable();
     let mut ast: Vec<Ast> = Vec::new();
     while tokens.peek().is_some() {
-        ast.push(parse_expr(&mut tokens));
+        ast.push(parse_expr(&mut tokens)?);
     }
-    Ast::Root(ast)
-}
\ No newline at end of file
+    Ok(Ast::Root(ast))
+}
+
+pub fn parse_string(src: &str) -> Result<Ast, ParseError> {
+    let tokens = tokenize(src);
+    parse(tokens)
+}
diff --git a/src/parser/tests.rs b/src/parser/tests.rs
index dd6a947..88f38cf 100644
--- a/src/parser/tests.rs
+++ b/src/parser/tests.rs
@@ -1,22 +1,38 @@
-use crate::parser::{tokenize, parse, Token, Ast};
+use crate::parser::{Ast, Localised, Token, parse, tokenize};
 
 #[test]
 fn test_tokenize() {
     let input = "(+ (* 1:u8 2) 2)";
     let expected = vec![
-        Token::LeftParen,
-        Token::Symbol("+".to_string()),
-        Token::LeftParen,
-        Token::Symbol("*".to_string()),
-        Token::Symbol("1:u8".to_string()),
-        Token::Symbol("2".to_string()),
-        Token::RightParen,
-        Token::Symbol("2".to_string()),
-        Token::RightParen,
+        Localised::dummy_location(Token::LeftParen),
+        Localised::dummy_location(Token::Symbol("+".to_string())),
+        Localised::dummy_location(Token::LeftParen),
+        Localised::dummy_location(Token::Symbol("*".to_string())),
+        Localised::dummy_location(Token::Symbol("1:u8".to_string())),
+        Localised::dummy_location(Token::Symbol("2".to_string())),
+        Localised::dummy_location(Token::RightParen),
+        Localised::dummy_location(Token::Symbol("2".to_string())),
+        Localised::dummy_location(Token::RightParen),
     ];
     assert_eq!(tokenize(input), expected);
 }
 
+#[test]
+#[should_panic]
+fn test_unexpected_pclose() {
+    let input = "())";
+    let tokens = tokenize(input);
+    let _ast = parse(tokens).unwrap();
+}
+
+#[test]
+#[should_panic]
+fn test_unexpected_eof() {
+    let input = "(1 2 3 4";
+    let tokens = tokenize(input);
+    let _ast = parse(tokens).unwrap();
+}
+
 #[test]
 fn test_parse() {
     let src = "
@@ -34,92 +50,92 @@ fn test_parse() {
             1.0 
             1.0)))
 ";
-    let ast = parse(tokenize(src));
+    let ast = parse(tokenize(src)).unwrap();
     println!("{:?}", ast);
     let test_ast: Ast = Ast::Root(vec![
-        Ast::List(vec![
-            Ast::Symbol("module".to_string()),
-            Ast::Symbol("Shader".to_string()),
-            Ast::Symbol("Logical".to_string()),
-            Ast::Symbol("GLSL450".to_string()),
-        ]),
-        Ast::List(vec![
-            Ast::Symbol("import".to_string()),
-            Ast::Symbol(":std".to_string()),
-            Ast::Symbol("GLSL.std.450".to_string()),
-        ]),
-        Ast::List(vec![
-            Ast::Symbol("bind".to_string()),
-            Ast::List(vec![
-                Ast::Symbol("frag-coord:*v4f32i".to_string()),
-            ]),
-            Ast::List(vec![
-                Ast::Symbol("BuiltIn".to_string()),
-                Ast::Symbol("FragCoord".to_string()),
-            ]),
-        ]),
-        Ast::List(vec![
-            Ast::Symbol("bind".to_string()),
-            Ast::List(vec![
-                Ast::Symbol("out-color:*v4f32o".to_string()),
-            ]),
-            Ast::List(vec![
-                Ast::Symbol("Location".to_string()),
-                Ast::Symbol("0".to_string()),
-            ]),
-        ]),
-        Ast::List(vec![
-            Ast::Symbol("dec".to_string()),
-            Ast::Symbol("frag-coord:*v4f32i".to_string()),
-            Ast::Symbol("Input".to_string()),
-        ]),
-        Ast::List(vec![
-            Ast::Symbol("dec".to_string()),
-            Ast::Symbol("out-color:*v4f32o".to_string()),
-            Ast::Symbol("Output".to_string()),
-        ]),
-        Ast::List(vec![
-            Ast::Symbol("entry".to_string()),
-            Ast::Symbol("main".to_string()),
-            Ast::Symbol("Fragment".to_string()),
-            Ast::Symbol("OriginUpperLeft".to_string()),
-            Ast::List(vec![
-                Ast::Symbol(":frag-coord".to_string()),
-                Ast::Symbol(":out-color".to_string()),
-            ]),
-        ]),
-        Ast::List(vec![
-            Ast::Symbol("fun".to_string()),
-            Ast::List(vec![
-                Ast::Symbol("main".to_string()),
-            ]),
-            Ast::List(vec![
-                Ast::Symbol("store-ptr".to_string()),
-                Ast::List(vec![
-                    Ast::Symbol("out-color".to_string()),
-                ]),
-                Ast::List(vec![
-                    Ast::Symbol("v4f32i".to_string()),
-                    Ast::List(vec![
-                        Ast::Symbol("/".to_string()),
-                        Ast::List(vec![
-                            Ast::Symbol(".xy".to_string()),
-                            Ast::List(vec![
-                                Ast::Symbol("load-ptr".to_string()),
-                                Ast::Symbol("frag-coord".to_string()),
-                            ]),
-                        ]),
-                        Ast::List(vec![
-                            Ast::Symbol("v2f32".to_string()),
-                            Ast::Symbol("1920.0".to_string()),
-                            Ast::Symbol("1080.0".to_string()),
-                        ]),
-                    ]),
-                    Ast::Symbol("1.0".to_string()),
-                    Ast::Symbol("1.0".to_string()),
-                ]),
-            ]),
-        ]),
+        Ast::List(Localised::dummy_location(vec![
+            Ast::Symbol(Localised::dummy_location("module".to_string())),
+            Ast::Symbol(Localised::dummy_location("Shader".to_string())),
+            Ast::Symbol(Localised::dummy_location("Logical".to_string())),
+            Ast::Symbol(Localised::dummy_location("GLSL450".to_string())),
+        ])),
+        Ast::List(Localised::dummy_location(vec![
+            Ast::Symbol(Localised::dummy_location("import".to_string())),
+            Ast::Symbol(Localised::dummy_location(":std".to_string())),
+            Ast::Symbol(Localised::dummy_location("GLSL.std.450".to_string())),
+        ])),
+        Ast::List(Localised::dummy_location(vec![
+            Ast::Symbol(Localised::dummy_location("bind".to_string())),
+            Ast::List(Localised::dummy_location(vec![Ast::Symbol(
+                Localised::dummy_location("frag-coord:*v4f32i".to_string()),
+            )])),
+            Ast::List(Localised::dummy_location(vec![
+                Ast::Symbol(Localised::dummy_location("Builtin".to_string())),
+                Ast::Symbol(Localised::dummy_location("FragCoord".to_string())),
+            ])),
+        ])),
+        Ast::List(Localised::dummy_location(vec![
+            Ast::Symbol(Localised::dummy_location("bind".to_string())),
+            Ast::List(Localised::dummy_location(vec![Ast::Symbol(
+                Localised::dummy_location("out-color:*v4f32o".to_string()),
+            )])),
+            Ast::List(Localised::dummy_location(vec![
+                Ast::Symbol(Localised::dummy_location("Location".to_string())),
+                Ast::Symbol(Localised::dummy_location("0".to_string())),
+            ])),
+        ])),
+        Ast::List(Localised::dummy_location(vec![
+            Ast::Symbol(Localised::dummy_location("dec".to_string())),
+            Ast::Symbol(Localised::dummy_location("frag-coord:*v4f32i".to_string())),
+            Ast::Symbol(Localised::dummy_location("Input".to_string())),
+        ])),
+        Ast::List(Localised::dummy_location(vec![
+            Ast::Symbol(Localised::dummy_location("dec".to_string())),
+            Ast::Symbol(Localised::dummy_location("out-color:*v4f32o".to_string())),
+            Ast::Symbol(Localised::dummy_location("Output".to_string())),
+        ])),
+        Ast::List(Localised::dummy_location(vec![
+            Ast::Symbol(Localised::dummy_location("entry".to_string())),
+            Ast::Symbol(Localised::dummy_location("main".to_string())),
+            Ast::Symbol(Localised::dummy_location("Fragment".to_string())),
+            Ast::Symbol(Localised::dummy_location("OriginUpperLeft".to_string())),
+            Ast::List(Localised::dummy_location(vec![
+                Ast::Symbol(Localised::dummy_location(":frag-coord".to_string())),
+                Ast::Symbol(Localised::dummy_location(":out-color".to_string())),
+            ])),
+        ])),
+        Ast::List(Localised::dummy_location(vec![
+            Ast::Symbol(Localised::dummy_location("fun".to_string())),
+            Ast::List(Localised::dummy_location(vec![Ast::Symbol(
+                Localised::dummy_location("main".to_string()),
+            )])),
+            Ast::List(Localised::dummy_location(vec![
+                Ast::Symbol(Localised::dummy_location("store-ptr".to_string())),
+                Ast::List(Localised::dummy_location(vec![Ast::Symbol(
+                    Localised::dummy_location("out-color".to_string()),
+                )])),
+                Ast::List(Localised::dummy_location(vec![
+                    Ast::Symbol(Localised::dummy_location("v4f23i".to_string())),
+                    Ast::List(Localised::dummy_location(vec![
+                        Ast::Symbol(Localised::dummy_location("/".to_string())),
+                        Ast::List(Localised::dummy_location(vec![
+                            Ast::Symbol(Localised::dummy_location(".xy".to_string())),
+                            Ast::List(Localised::dummy_location(vec![
+                                Ast::Symbol(Localised::dummy_location("load-ptr".to_string())),
+                                Ast::Symbol(Localised::dummy_location("frag-coord".to_string())),
+                            ])),
+                        ])),
+                        Ast::List(Localised::dummy_location(vec![
+                            Ast::Symbol(Localised::dummy_location("v2f32".to_string())),
+                            Ast::Symbol(Localised::dummy_location("1920.0".to_string())),
+                            Ast::Symbol(Localised::dummy_location("1080.0".to_string())),
+                        ])),
+                    ])),
+                    Ast::Symbol(Localised::dummy_location("1.0".to_string())),
+                    Ast::Symbol(Localised::dummy_location("1.0".to_string())),
+                ])),
+            ])),
+        ])),
     ]);
     assert_eq!(ast, test_ast);
-}
\ No newline at end of file
+}