diff --git a/src/main.rs b/src/main.rs
index 1851f55..bd92ff5 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -2,8 +2,10 @@ extern crate regex;
 
 use std::io::prelude::*;
 
-use std::{io, fs, env};
+use std::{io, fs, env, fmt};
 use std::collections::{HashSet, BTreeMap};
+use std::fmt::Display;
+use regex::Regex;
 
 macro_rules! warn {
   ($($arg:tt)*) => {{
@@ -20,63 +22,239 @@ macro_rules! die {
   }};
 }
 
-fn re(pattern: &str) -> regex::Regex {
-  regex::Regex::new(pattern).unwrap()
+trait Slurp {
+  fn slurp(&mut self) -> Result<String, std::io::Error>;
+}
+
+impl Slurp for fs::File {
+  fn slurp(&mut self) -> Result<String, std::io::Error> {
+    let mut destination = String::new();
+    try!(self.read_to_string(&mut destination));
+    Ok(destination)
+  }
+}
+
+fn re(pattern: &str) -> Regex {
+  Regex::new(pattern).unwrap()
 }
 
 struct Recipe<'a> {
-  _line:               u64,
+  line:               usize,
   name:               &'a str,
   leading_whitespace: &'a str,
   commands:           Vec<&'a str>,
   dependencies:       HashSet<&'a str>,
 }
 
-struct Resolver<'a> {
-  recipes:  &'a BTreeMap<&'a str, Recipe<'a>>,
-  resolved: HashSet<&'a str>,
-  seen:     HashSet<&'a str>,
-  stack:    Vec<&'a str>,
+struct Error<'a> {
+  text: &'a str,
+  line: usize,
+  kind: ErrorKind<'a>
 }
 
-fn resolve<'a> (recipes: &'a BTreeMap<&'a str, Recipe<'a>>) {
-  let mut resolver = Resolver {
-    recipes:  recipes,
-    resolved: HashSet::new(),
-    seen:     HashSet::new(),
-    stack:    vec![],
-  };
+enum ErrorKind<'a> {
+  CircularDependency{circle: Vec<&'a str>},
+  DuplicateDependency{name: &'a str},
+  DuplicateRecipe{first: usize, name: &'a str},
+  InconsistentLeadingWhitespace{expected: &'a str, found: &'a str},
+  Shebang,
+  UnknownDependency{name: &'a str, unknown: &'a str},
+  Unparsable,
+  UnparsableDependencies,
+}
 
-  for (_, recipe) in recipes {
-    resolver.resolve(recipe);
+fn error<'a>(text: &'a str, line: usize, kind: ErrorKind<'a>) 
+  -> Error<'a>
+{
+  Error {
+    text: text,
+    line: line,
+    kind: kind,
   }
 }
 
-impl<'a> Resolver<'a> {
-  fn resolve(&mut self, recipe: &'a Recipe) {
-    self.stack.push(recipe.name);
-    self.seen.insert(recipe.name);
-    for dependency_name in &recipe.dependencies {
-      match self.recipes.get(dependency_name) {
-        Some(dependency) => if !self.resolved.contains(dependency.name) {
-          if self.seen.contains(dependency.name) {
-            let first = self.stack[0];
-            self.stack.push(first);
-            die!("Circular dependency: {}",
-              self.stack.iter()
-                .skip_while(|name| **name != dependency.name)
-                .cloned().collect::<Vec<&str>>().join(" -> "));
+fn show_whitespace(text: &str) -> String {
+  text.chars().map(|c| match c { '\t' => 't', ' ' => 's', _ => c }).collect()
+}
+
+impl<'a> Display for Error<'a> {
+  fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
+    try!(write!(f, "justfile:{}: ", self.line));
+
+    match self.kind {
+      ErrorKind::CircularDependency{ref circle} => {
+        try!(write!(f, "circular dependency: {}", circle.join(" -> ")));
+        return Ok(());
+      }
+      ErrorKind::DuplicateDependency{name} => {
+        try!(writeln!(f, "duplicate dependency: {}", name));
+      }
+      ErrorKind::DuplicateRecipe{first, name} => {
+        try!(write!(f, "duplicate recipe: {} appears on lines {} and {}", 
+                    name, first, self.line));
+        return Ok(());
+      }
+      ErrorKind::InconsistentLeadingWhitespace{expected, found} => {
+        try!(writeln!(f,
+          "inconsistant leading whitespace: recipe started with {} but found line with {}:",
+          show_whitespace(expected), show_whitespace(found)
+        ));
+      }
+      ErrorKind::Shebang => {
+        try!(writeln!(f, "shebang \"#!\" is reserved syntax"))
+      }
+      ErrorKind::UnknownDependency{name, unknown} => {
+        try!(writeln!(f, "recipe {} has unknown dependency {}", name, unknown));
+      }
+      ErrorKind::Unparsable => {
+        try!(writeln!(f, "could not parse line:"));
+      }
+      ErrorKind::UnparsableDependencies => {
+        try!(writeln!(f, "could not parse dependencies:"));
+      }
+    }
+
+    match self.text.lines().nth(self.line) {
+      Some(line) => try!(write!(f, "{}", line)),
+      None => die!("internal error: Error has invalid line number: {}", self.line),
+    }
+
+    Ok(())
+  }
+}
+
+struct Justfile<'a> {
+  _recipes: BTreeMap<&'a str, Recipe<'a>>
+}
+
+fn parse<'a>(text: &'a str) -> Result<Justfile, Error> {
+  let shebang_re    = re(r"^\s*#!(.*)$");
+  let comment_re    = re(r"^\s*#[^!].*$");
+  let command_re    = re(r"^(\s+)(.*)$");
+  let blank_re      = re(r"^\s*$");
+  let label_re      = re(r"^([a-z](-[a-z]|[a-z])*):(.*)$");
+  let name_re       = re(r"^[a-z](-[a-z]|[a-z])*$");
+  let whitespace_re = re(r"\s+");
+
+  let mut recipes: BTreeMap<&'a str, Recipe<'a>> = BTreeMap::new();
+  let mut current_recipe: Option<Recipe> = None;
+  for (i, line) in text.lines().enumerate() {
+    if blank_re.is_match(line) {
+      continue;
+    } else if shebang_re.is_match(line) {
+      return Err(error(text, i, ErrorKind::Shebang));
+    }
+
+    if let Some(mut recipe) = current_recipe {
+      match command_re.captures(line) {
+        Some(captures) => {
+          let leading_whitespace = captures.at(1).unwrap();
+          if recipe.leading_whitespace == "" {
+            recipe.leading_whitespace = leading_whitespace;
+          } else if !line.starts_with(recipe.leading_whitespace) {
+            return Err(error(text, i, ErrorKind::InconsistentLeadingWhitespace{
+              expected: recipe.leading_whitespace,
+              found:    leading_whitespace,
+            }));
           }
-          self.resolve(dependency);
+          let command = captures.at(2).unwrap();
+          recipe.commands.push(command);
+          current_recipe = Some(recipe);
+          continue;
         },
-        None => die!("Recipe \"{}\" depends on recipe \"{}\", which doesn't exist.",
-          recipe.name, dependency_name),
+        None => {
+          recipes.insert(recipe.name, recipe);
+          current_recipe = None;
+        },
+      }
+    }
+    
+    if comment_re.is_match(line) {
+      // ignore
+    } else if let Some(captures) = label_re.captures(line) {
+      let name = captures.at(1).unwrap();
+      if let Some(recipe) = recipes.get(name) {
+        return Err(error(text, i, ErrorKind::DuplicateRecipe {
+          first: recipe.line,
+          name: name,
+        }));
       }
 
+      let rest = captures.at(3).unwrap().trim();
+      let mut dependencies = HashSet::new();
+      for part in whitespace_re.split(rest) {
+        if name_re.is_match(part) {
+          if dependencies.contains(part) {
+            return Err(error(text, i, ErrorKind::DuplicateDependency{
+              name: part,
+            }));
+          }
+          dependencies.insert(part);
+        } else {
+          return Err(error(text, i, ErrorKind::UnparsableDependencies));
+        }
+      }
+
+      current_recipe = Some(Recipe{
+        line:               i,
+        name:               name,
+        leading_whitespace: "",
+        commands:           vec![],
+        dependencies:      dependencies,
+      });
+    } else {
+      return Err(error(text, i, ErrorKind::Unparsable));
     }
-    self.resolved.insert(recipe.name);
-    self.stack.pop();
   }
+
+  if let Some(recipe) = current_recipe {
+    recipes.insert(recipe.name, recipe);
+  }
+
+  let mut resolved = HashSet::new();
+  let mut seen     = HashSet::new();
+  let mut stack    = vec![];
+
+  fn resolve<'a>(
+    text:     &'a str,
+    recipes:  &BTreeMap<&str, Recipe<'a>>,
+    resolved: &mut HashSet<&'a str>,
+    seen:     &mut HashSet<&'a str>,
+    stack:    &mut Vec<&'a str>,
+    recipe:   &Recipe<'a>,
+  ) -> Result<(), Error<'a>> {
+    stack.push(recipe.name);
+    seen.insert(recipe.name);
+    for dependency_name in &recipe.dependencies {
+      match recipes.get(dependency_name) {
+        Some(dependency) => if !resolved.contains(dependency.name) {
+          if seen.contains(dependency.name) {
+            let first = stack[0];
+            stack.push(first);
+            return Err(error(text, recipe.line, ErrorKind::CircularDependency {
+              circle: stack.iter()
+                .skip_while(|name| **name != dependency.name)
+                .cloned().collect()
+            }));
+          }
+          return resolve(text, recipes, resolved, seen, stack, dependency);
+        },
+        None => return Err(error(text, recipe.line, ErrorKind::UnknownDependency {
+          name:    recipe.name,
+          unknown: dependency_name
+        })),
+      }
+    }
+    resolved.insert(recipe.name);
+    stack.pop();
+    Ok(())
+  }
+
+  for (_, ref recipe) in &recipes {
+    try!(resolve(text, &recipes, &mut resolved, &mut seen, &mut stack, &recipe));
+  }
+
+  Ok(Justfile{_recipes: recipes})
 }
 
 fn main() {
@@ -100,91 +278,14 @@ fn main() {
     }
   }
 
-  let mut contents = String::new();
-
-  fs::File::open("justfile")
+  let text = fs::File::open("justfile")
     .unwrap_or_else(|error| die!("Error opening justfile: {}", error))
-    .read_to_string(&mut contents)
+    .slurp()
     .unwrap_or_else(|error| die!("Error reading justfile: {}", error));
 
-  let shebang_re    = re(r"^\s*#!(.*)$");
-  let comment_re    = re(r"^\s*#[^!].*$");
-  let command_re    = re(r"^(\s+)(.*)$");
-  let blank_re      = re(r"^\s*$");
-  let label_re      = re(r"^([a-z](-[a-z]|[a-z])*):(.*)$");
-  let name_re       = re(r"^[a-z](-[a-z]|[a-z])*$");
-  let whitespace_re = re(r"\s+");
-
-  let mut recipes = BTreeMap::new();
-  let mut current_recipe: Option<Recipe> = None;
-  for (i, line) in contents.lines().enumerate() {
-    if blank_re.is_match(line) {
-      continue;
-    } else if shebang_re.is_match(line) {
-      die!("Unexpected shebang on line {}: {}", i, line);
-    }
-
-    if let Some(mut recipe) = current_recipe {
-      match command_re.captures(line) {
-        Some(captures) => {
-          let leading_whitespace = captures.at(1).unwrap();
-          if recipe.leading_whitespace == "" {
-            recipe.leading_whitespace = leading_whitespace;
-          } else if leading_whitespace != recipe.leading_whitespace {
-            die!("Command on line {} has inconsistent leading whitespace: {}",
-              i, line);
-          }
-          let command = captures.at(2).unwrap();
-          recipe.commands.push(command);
-          current_recipe = Some(recipe);
-          continue;
-        },
-        None => {
-          recipes.insert(recipe.name, recipe);
-          current_recipe = None;
-        },
-      }
-    }
-    
-    if comment_re.is_match(line) {
-      // ignore
-    } else if let Some(captures) = label_re.captures(line) {
-      let name = captures.at(1).unwrap();
-      let rest = captures.at(3).unwrap().trim();
-      let mut dependencies = HashSet::new();
-      for part in whitespace_re.split(rest) {
-        if name_re.is_match(part) {
-          if dependencies.contains(part) {
-            die!("Duplicate dependency \"{}\" on line {}", part, i);
-          }
-          dependencies.insert(part);
-        } else {
-          die!("Bad label on line {}: {}", i, line);
-        }
-      }
-      
-      if recipes.contains_key(name) {
-        die!("Duplicate recipe name \"{}\" on line {}.", name, i);
-      }
-
-      current_recipe = Some(Recipe{
-        _line:               i as u64,
-        name:               name,
-        leading_whitespace: "",
-        commands:           vec![],
-        dependencies:      dependencies,
-      });
-    } else {
-      die!("Error parsing line {} of justfile: {}", i, line);
-    }
-  }
-
-  if let Some(recipe) = current_recipe {
-    recipes.insert(recipe.name, recipe);
-  }
-
-  resolve(&recipes);
+  let _justfile = parse(&text).unwrap_or_else(|error| die!("{}", error));
 
+  /*
   // let requests: Vec<String> = std::env::args().skip(1).collect();
   // for request in requests {
   //   println!("{}", request);
@@ -196,7 +297,6 @@ fn main() {
     // std::env::set_var(format!("ARG{}", i), argument);
   // }
 
-  /*
   let mut command = std::process::Command::new(make.command());
 
   command.arg("MAKEFLAGS=");