diff --git a/include/bolt/CST.hpp b/include/bolt/CST.hpp
index ee4d71a6c..5dff45223 100644
--- a/include/bolt/CST.hpp
+++ b/include/bolt/CST.hpp
@@ -1,6 +1,7 @@
 #ifndef BOLT_CST_HPP
 #define BOLT_CST_HPP
 
+#include <iterator>
 #include <vector>
 
 #include "bolt/Text.hpp"
@@ -57,29 +58,41 @@ namespace bolt {
     SourceFile,
   };
 
+  class Token;
+  class SourceFile;
 
   class Node {
 
-    unsigned refcount = 0;
+    unsigned RefCount = 0;
 
   public:
 
+    Node* Parent = nullptr;
+
     inline void ref() {
-      ++refcount;
+      ++RefCount;
     }
 
     inline void unref() {
-      --refcount;
-      if (refcount == 0) {
+      --RefCount;
+      if (RefCount == 0) {
         delete this;
       }
     }
 
+    virtual void setParents() = 0;
+    
+    virtual Token* getFirstToken() = 0;
+    virtual Token* getLastToken() = 0;
+
+    TextRange getRange();
+
     const NodeType Type;
 
     inline Node(NodeType Type):
         Type(Type) {}
 
+    SourceFile* getSourceFile();
 
     virtual ~Node();
 
@@ -95,6 +108,16 @@ namespace bolt {
 
     virtual std::string getText() const = 0;
 
+    void setParents() override;
+
+    inline Token* getFirstToken() override {
+      return this;
+    }
+
+    inline Token* getLastToken() override {
+      return this;
+    }
+
     inline TextLoc getStartLoc() {
       return StartLoc;
     }
@@ -128,7 +151,8 @@ namespace bolt {
   class Equals : public Token {
   public:
 
-    Equals(TextLoc StartLoc): Token(NodeType::Equals, StartLoc) {}
+    Equals(TextLoc StartLoc):
+      Token(NodeType::Equals, StartLoc) {}
 
     std::string getText() const override;
 
@@ -139,7 +163,8 @@ namespace bolt {
   class Colon : public Token {
   public:
 
-    Colon(TextLoc StartLoc): Token(NodeType::Colon, StartLoc) {}
+    Colon(TextLoc StartLoc):
+      Token(NodeType::Colon, StartLoc) {}
 
     std::string getText() const override;
 
@@ -150,7 +175,8 @@ namespace bolt {
   class Dot : public Token {
   public:
 
-    Dot(TextLoc StartLoc): Token(NodeType::Dot, StartLoc) {}
+    Dot(TextLoc StartLoc):
+      Token(NodeType::Dot, StartLoc) {}
 
     std::string getText() const override;
 
@@ -161,7 +187,8 @@ namespace bolt {
   class DotDot : public Token {
   public:
 
-    DotDot(TextLoc StartLoc): Token(NodeType::DotDot, StartLoc) {}
+    DotDot(TextLoc StartLoc):
+      Token(NodeType::DotDot, StartLoc) {}
 
     std::string getText() const override;
 
@@ -172,7 +199,8 @@ namespace bolt {
   class LParen : public Token {
   public:
 
-    LParen(TextLoc StartLoc): Token(NodeType::LParen, StartLoc) {}
+    LParen(TextLoc StartLoc):
+      Token(NodeType::LParen, StartLoc) {}
 
     std::string getText() const override;
 
@@ -183,7 +211,8 @@ namespace bolt {
   class RParen : public Token {
   public:
 
-    RParen(TextLoc StartLoc): Token(NodeType::RParen, StartLoc) {}
+    RParen(TextLoc StartLoc):
+      Token(NodeType::RParen, StartLoc) {}
 
     std::string getText() const override;
 
@@ -194,7 +223,8 @@ namespace bolt {
   class LBracket : public Token {
   public:
 
-    LBracket(TextLoc StartLoc): Token(NodeType::LBracket, StartLoc) {}
+    LBracket(TextLoc StartLoc):
+      Token(NodeType::LBracket, StartLoc) {}
 
     std::string getText() const override;
 
@@ -205,7 +235,8 @@ namespace bolt {
   class RBracket : public Token {
   public:
 
-    RBracket(TextLoc StartLoc): Token(NodeType::RBracket, StartLoc) {}
+    RBracket(TextLoc StartLoc):
+      Token(NodeType::RBracket, StartLoc) {}
 
     std::string getText() const override;
 
@@ -216,7 +247,8 @@ namespace bolt {
   class LBrace : public Token {
   public:
 
-    LBrace(TextLoc StartLoc): Token(NodeType::LBrace, StartLoc) {}
+    LBrace(TextLoc StartLoc):
+      Token(NodeType::LBrace, StartLoc) {}
 
     std::string getText() const override;
 
@@ -227,7 +259,8 @@ namespace bolt {
   class RBrace : public Token {
   public:
 
-    RBrace(TextLoc StartLoc): Token(NodeType::RBrace, StartLoc) {}
+    RBrace(TextLoc StartLoc):
+      Token(NodeType::RBrace, StartLoc) {}
 
     std::string getText() const override;
 
@@ -238,7 +271,8 @@ namespace bolt {
   class LetKeyword : public Token {
   public:
 
-    LetKeyword(TextLoc StartLoc): Token(NodeType::LetKeyword, StartLoc) {}
+    LetKeyword(TextLoc StartLoc):
+      Token(NodeType::LetKeyword, StartLoc) {}
 
     std::string getText() const override;
 
@@ -249,7 +283,8 @@ namespace bolt {
   class MutKeyword : public Token {
   public:
 
-    MutKeyword(TextLoc StartLoc): Token(NodeType::MutKeyword, StartLoc) {}
+    MutKeyword(TextLoc StartLoc):
+      Token(NodeType::MutKeyword, StartLoc) {}
 
     std::string getText() const override;
 
@@ -260,7 +295,8 @@ namespace bolt {
   class PubKeyword : public Token {
   public:
 
-    PubKeyword(TextLoc StartLoc): Token(NodeType::PubKeyword, StartLoc) {}
+    PubKeyword(TextLoc StartLoc):
+      Token(NodeType::PubKeyword, StartLoc) {}
 
     std::string getText() const override;
 
@@ -271,7 +307,8 @@ namespace bolt {
   class TypeKeyword : public Token {
   public:
 
-    TypeKeyword(TextLoc StartLoc): Token(NodeType::TypeKeyword, StartLoc) {}
+    TypeKeyword(TextLoc StartLoc):
+      Token(NodeType::TypeKeyword, StartLoc) {}
 
     std::string getText() const override;
 
@@ -282,7 +319,8 @@ namespace bolt {
   class ReturnKeyword : public Token {
   public:
 
-    ReturnKeyword(TextLoc StartLoc): Token(NodeType::ReturnKeyword, StartLoc) {}
+    ReturnKeyword(TextLoc StartLoc):
+      Token(NodeType::ReturnKeyword, StartLoc) {}
 
     std::string getText() const override;
 
@@ -293,7 +331,8 @@ namespace bolt {
   class ModKeyword : public Token {
   public:
 
-    ModKeyword(TextLoc StartLoc): Token(NodeType::ModKeyword, StartLoc) {}
+    ModKeyword(TextLoc StartLoc):
+      Token(NodeType::ModKeyword, StartLoc) {}
 
     std::string getText() const override;
 
@@ -304,7 +343,8 @@ namespace bolt {
   class StructKeyword : public Token {
   public:
 
-    StructKeyword(TextLoc StartLoc): Token(NodeType::StructKeyword, StartLoc) {}
+    StructKeyword(TextLoc StartLoc):
+      Token(NodeType::StructKeyword, StartLoc) {}
 
     std::string getText() const override;
 
@@ -315,7 +355,8 @@ namespace bolt {
   class Invalid : public Token {
   public:
 
-    Invalid(TextLoc StartLoc): Token(NodeType::Invalid, StartLoc) {}
+    Invalid(TextLoc StartLoc):
+      Token(NodeType::Invalid, StartLoc) {}
 
     std::string getText() const override;
 
@@ -326,7 +367,8 @@ namespace bolt {
   class EndOfFile : public Token {
   public:
 
-    EndOfFile(TextLoc StartLoc): Token(NodeType::EndOfFile, StartLoc) {}
+    EndOfFile(TextLoc StartLoc):
+      Token(NodeType::EndOfFile, StartLoc) {}
 
     std::string getText() const override;
 
@@ -337,7 +379,8 @@ namespace bolt {
   class BlockStart : public Token {
   public:
 
-    BlockStart(TextLoc StartLoc): Token(NodeType::BlockStart, StartLoc) {}
+    BlockStart(TextLoc StartLoc):
+      Token(NodeType::BlockStart, StartLoc) {}
 
     std::string getText() const override;
 
@@ -348,7 +391,8 @@ namespace bolt {
   class BlockEnd : public Token {
   public:
 
-    BlockEnd(TextLoc StartLoc): Token(NodeType::BlockEnd, StartLoc) {}
+    BlockEnd(TextLoc StartLoc):
+      Token(NodeType::BlockEnd, StartLoc) {}
 
     std::string getText() const override;
 
@@ -359,7 +403,8 @@ namespace bolt {
   class LineFoldEnd : public Token {
   public:
 
-    LineFoldEnd(TextLoc StartLoc): Token(NodeType::LineFoldEnd, StartLoc) {}
+    LineFoldEnd(TextLoc StartLoc):
+      Token(NodeType::LineFoldEnd, StartLoc) {}
 
     std::string getText() const override;
 
@@ -372,7 +417,8 @@ namespace bolt {
 
     ByteString Text;
 
-    CustomOperator(ByteString Text, TextLoc StartLoc): Token(NodeType::CustomOperator, StartLoc), Text(Text) {}
+    CustomOperator(ByteString Text, TextLoc StartLoc):
+      Token(NodeType::CustomOperator, StartLoc), Text(Text) {}
 
     std::string getText() const override;
 
@@ -385,7 +431,8 @@ namespace bolt {
 
     ByteString Text;
 
-    Assignment(ByteString Text, TextLoc StartLoc): Token(NodeType::Assignment, StartLoc), Text(Text) {}
+    Assignment(ByteString Text, TextLoc StartLoc):
+      Token(NodeType::Assignment, StartLoc), Text(Text) {}
 
     std::string getText() const override;
 
@@ -398,7 +445,8 @@ namespace bolt {
 
     ByteString Text;
 
-    Identifier(ByteString Text, TextLoc StartLoc): Token(NodeType::Identifier, StartLoc), Text(Text) {}
+    Identifier(ByteString Text, TextLoc StartLoc):
+      Token(NodeType::Identifier, StartLoc), Text(Text) {}
 
     std::string getText() const override;
 
@@ -411,7 +459,8 @@ namespace bolt {
 
     ByteString Text;
 
-    StringLiteral(ByteString Text, TextLoc StartLoc): Token(NodeType::StringLiteral, StartLoc), Text(Text) {}
+    StringLiteral(ByteString Text, TextLoc StartLoc):
+      Token(NodeType::StringLiteral, StartLoc), Text(Text) {}
 
     std::string getText() const override;
 
@@ -424,7 +473,8 @@ namespace bolt {
 
     Integer Value;
 
-    IntegerLiteral(Integer Value, TextLoc StartLoc): Token(NodeType::IntegerLiteral, StartLoc), Value(Value) {}
+    IntegerLiteral(Integer Value, TextLoc StartLoc):
+      Token(NodeType::IntegerLiteral, StartLoc), Value(Value) {}
 
     std::string getText() const override;
 
@@ -445,6 +495,11 @@ namespace bolt {
        ModulePath(ModulePath),
        Name(Name) {}
 
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
+    void setParents() override;
+
     ~QualifiedName();
 
   };
@@ -468,6 +523,11 @@ namespace bolt {
     ): TypeExpression(NodeType::ReferenceTypeExpression),
        Name(Name) {}
 
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~ReferenceTypeExpression();
 
   };
@@ -491,6 +551,11 @@ namespace bolt {
     ): Pattern(NodeType::BindPattern),
        Name(Name) {}
 
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~BindPattern();
 
   };
@@ -507,13 +572,18 @@ namespace bolt {
   class ReferenceExpression : public Expression {
   public:
 
-    Identifier* Name;
+    QualifiedName* Name;
 
     ReferenceExpression(
-      Identifier* Name
+      QualifiedName* Name
     ): Expression(NodeType::ReferenceExpression),
        Name(Name) {}
 
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~ReferenceExpression();
 
   };
@@ -528,6 +598,11 @@ namespace bolt {
     ): Expression(NodeType::ConstantExpression),
        Token(Token) {}
 
+    void setParents() override;
+
+    class Token* getFirstToken() override;
+    class Token* getLastToken() override;
+
     ~ConstantExpression();
 
   };
@@ -535,11 +610,21 @@ namespace bolt {
   class CallExpression : public Expression {
   public:
 
-    CallExpression(Expression* Function, std::vector<Expression*> Args): Expression(NodeType::CallExpression), Function(Function), Args(Args) {}
-
     Expression* Function;
     std::vector<Expression*> Args;
 
+    CallExpression(
+      Expression* Function,
+      std::vector<Expression*> Args
+    ): Expression(NodeType::CallExpression),
+       Function(Function),
+       Args(Args) {}
+
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~CallExpression();
 
   };
@@ -557,6 +642,11 @@ namespace bolt {
       Operator(Operator),
       RHS(RHS) {}
 
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~InfixExpression();
 
   };
@@ -574,6 +664,11 @@ namespace bolt {
        Operator(Operator),
        Argument(Argument) {}
 
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~UnaryExpression();
 
   };
@@ -590,10 +685,15 @@ namespace bolt {
   class ExpressionStatement : public Statement {
   public:
 
-    ExpressionStatement(Expression* Expression):
+    Expression* Expression;
+
+    ExpressionStatement(class Expression* Expression):
       Statement(NodeType::ExpressionStatement), Expression(Expression) {}
 
-    Expression* Expression;
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
 
     ~ExpressionStatement();
 
@@ -602,24 +702,43 @@ namespace bolt {
   class ReturnStatement : public Statement {
   public:
 
-    ReturnStatement(ReturnKeyword* ReturnKeyword, Expression* Expression): Statement(NodeType::ReturnStatement), ReturnKeyword(ReturnKeyword), Expression(Expression) {}
-
     ReturnKeyword* ReturnKeyword;
     Expression* Expression;
 
+    ReturnStatement(
+      class ReturnKeyword* ReturnKeyword,
+      class Expression* Expression
+    ): Statement(NodeType::ReturnStatement),
+       ReturnKeyword(ReturnKeyword),
+       Expression(Expression) {}
+
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~ReturnStatement();
 
   };
 
   class TypeAssert : public Node {
-
-    public:
-
-    TypeAssert(Colon* Colon, TypeExpression* TypeExpression): Node(NodeType::TypeAssert), Colon(Colon), TypeExpression(TypeExpression) {}
+  public:
 
     Colon* Colon;
     TypeExpression* TypeExpression;
 
+    TypeAssert(
+      class Colon* Colon,
+      class TypeExpression* TypeExpression
+    ): Node(NodeType::TypeAssert),
+       Colon(Colon),
+       TypeExpression(TypeExpression) {}
+
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~TypeAssert();
 
   };
@@ -632,6 +751,11 @@ namespace bolt {
     Pattern* Pattern;
     TypeAssert* TypeAssert;
 
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~Param();
 
   };
@@ -648,15 +772,20 @@ namespace bolt {
   class LetBlockBody : public LetBody {
   public:
 
+    BlockStart* BlockStart;
+    std::vector<Node*> Elements;
+
     LetBlockBody(
-      BlockStart* BlockStart,
+      class BlockStart* BlockStart,
       std::vector<Node*> Elements
     ): LetBody(NodeType::LetBlockBody),
        BlockStart(BlockStart),
        Elements(Elements) {}
 
-    BlockStart* BlockStart;
-    std::vector<Node*> Elements;
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
 
     ~LetBlockBody();
 
@@ -675,6 +804,11 @@ namespace bolt {
        Equals(Equals),
        Expression(Expression) {}
 
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~LetExprBody();
 
   };
@@ -683,7 +817,7 @@ namespace bolt {
   public:
 
     PubKeyword* PubKeyword;
-    LetKeyword* LetKeywod;
+    LetKeyword* LetKeyword;
     MutKeyword* MutKeyword;
     Pattern* Pattern;
     std::vector<Param*> Params;
@@ -700,13 +834,18 @@ namespace bolt {
       LetBody* Body
     ): Node(NodeType::LetDeclaration),
        PubKeyword(PubKeyword),
-       LetKeywod(LetKeywod),
+       LetKeyword(LetKeywod),
        MutKeyword(MutKeyword),
        Pattern(Pattern),
        Params(Params),
        TypeAssert(TypeAssert),
        Body(Body) {}
 
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~LetDeclaration();
 
   };
@@ -727,6 +866,11 @@ namespace bolt {
     Colon* Colon;
     TypeExpression* TypeExpression;
 
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~StructDeclField();
 
   };
@@ -734,35 +878,53 @@ namespace bolt {
   class StructDecl : public Node {
   public:
 
-    StructDecl(
-        StructKeyword* StructKeyword,
-        Identifier* Name,
-        Dot* Dot,
-        std::vector<StructDeclField*> Fields
-      ): Node(NodeType::StructDecl),
-         StructKeyword(StructKeyword),
-         Name(Name),
-         Dot(Dot),
-         Fields(Fields) {}
-
+    PubKeyword* PubKeyword;
     StructKeyword* StructKeyword;
     Identifier* Name;
-    Dot* Dot;
+    BlockStart* BlockStart;
     std::vector<StructDeclField*> Fields;
 
+    StructDecl(
+      class PubKeyword* PubKeyword,
+      class StructKeyword* StructKeyword,
+      Identifier* Name,
+      class BlockStart* BlockStart,
+      std::vector<StructDeclField*> Fields
+    ): Node(NodeType::StructDecl),
+       PubKeyword(PubKeyword),
+       StructKeyword(StructKeyword),
+       Name(Name),
+       BlockStart(BlockStart),
+       Fields(Fields) {}
+
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~StructDecl();
 
   };
 
   class SourceFile : public Node {
-
-    public:
-
-    SourceFile(std::vector<Node*> Elements):
-      Node(NodeType::SourceFile), Elements(Elements) {}
+  public:
+    
+    TextFile& File;
 
     std::vector<Node*> Elements;
 
+    SourceFile(TextFile& File, std::vector<Node*> Elements):
+      Node(NodeType::SourceFile), File(File), Elements(Elements) {}
+
+    inline TextFile& getTextFile() {
+      return File;
+    }
+
+    void setParents() override;
+
+    Token* getFirstToken() override;
+    Token* getLastToken() override;
+
     ~SourceFile();
 
   };
diff --git a/include/bolt/Diagnostics.hpp b/include/bolt/Diagnostics.hpp
index 4c50f5c76..eac875f05 100644
--- a/include/bolt/Diagnostics.hpp
+++ b/include/bolt/Diagnostics.hpp
@@ -98,12 +98,55 @@ namespace bolt {
 
   };
 
+  enum class Color {
+    None,
+    Black,
+    White,
+    Red,
+    Yellow,
+    Green,
+    Blue,
+    Cyan,
+    Magenta,
+  };
+
   class ConsoleDiagnostics : public DiagnosticEngine {
 
     std::ostream& Out;
 
+    void setForegroundColor(Color C);
+    void setBackgroundColor(Color C);
+    void resetStyles();
+
+    void writeGutter(
+      std::size_t GutterWidth,
+      std::size_t Line
+    );
+
+    void writeHighlight(
+      std::size_t GutterWidth,
+      TextRange Range,
+      Color HighlightColor,
+      std::size_t Line,
+      std::size_t LineLength
+    );
+
+    void writeExcerpt(
+      TextFile& File,
+      TextRange ToPrint,
+      TextRange ToHighlight,
+      Color HighlightColor
+    );
+
   public:
 
+    unsigned ExcerptLinesPre = 2;
+    unsigned ExcerptLinesPost = 2;
+    std::size_t MaxTypeSubsitutionCount = 0;
+    bool PrintFilePosition = true;
+    bool PrintExcerpts = true;
+    bool EnableColors = true;
+
     void addDiagnostic(const Diagnostic& Diagnostic) override;
 
     ConsoleDiagnostics(std::ostream& Out = std::cerr);
diff --git a/include/bolt/Parser.hpp b/include/bolt/Parser.hpp
index 7ac68eb51..1cbaa1752 100644
--- a/include/bolt/Parser.hpp
+++ b/include/bolt/Parser.hpp
@@ -60,6 +60,8 @@ namespace bolt {
 
   class Parser {
 
+    TextFile& File;
+
     Stream<Token*>& Tokens;
 
     OperatorTable ExprOperators;
@@ -70,7 +72,7 @@ namespace bolt {
 
   public:
 
-    Parser(Stream<Token*>& S);
+    Parser(TextFile& File, Stream<Token*>& S);
 
     QualifiedName* parseQualifiedName();
 
diff --git a/include/bolt/Text.hpp b/include/bolt/Text.hpp
index 7e27759ef..a576a618a 100644
--- a/include/bolt/Text.hpp
+++ b/include/bolt/Text.hpp
@@ -7,6 +7,7 @@
 #include <string>
 
 #include "bolt/ByteString.hpp"
+#include "bolt/String.hpp"
 
 namespace bolt {
 
@@ -38,21 +39,23 @@ namespace bolt {
   class TextFile {
 
     ByteString Path;
-    ByteString Text;
+    String Text;
 
     std::vector<size_t> LineOffsets;
 
   public:
 
-    TextFile(ByteString Path, ByteString Text);
+    TextFile(ByteString Path, String Text);
 
     size_t getLine(size_t Offset);
     size_t getColumn(size_t Offset);
     size_t getStartOffset(size_t Line);
 
+    size_t getLineCount() const;
+
     ByteString getPath() const;
 
-    ByteString getText() const;
+    String getText() const;
 
   };
 
diff --git a/src/CST.cc b/src/CST.cc
index c780feb51..46a5ce149 100644
--- a/src/CST.cc
+++ b/src/CST.cc
@@ -1,9 +1,168 @@
 
+#include "zen/config.hpp"
+
 #include "bolt/CST.hpp"
 
 namespace bolt {
 
-  Node::~Node() { }
+  SourceFile* Node::getSourceFile() {
+    auto CurrNode = this;
+    for (;;) {
+      if (CurrNode->Type == NodeType::SourceFile) {
+        return static_cast<SourceFile*>(this);
+      }
+      CurrNode = CurrNode->Parent;
+      ZEN_ASSERT(CurrNode != nullptr);
+    } 
+  }
+
+  TextRange Node::getRange() {
+    return TextRange {
+      getFirstToken()->getStartLoc(),
+      getLastToken()->getEndLoc(),
+    };
+  }
+
+  void Token::setParents() {
+  }
+
+  void QualifiedName::setParents() {
+    for (auto Name: ModulePath) {
+      Name->Parent = this;
+    }
+    Name->Parent = this;
+  }
+
+  void ReferenceTypeExpression::setParents() {
+    Name->Parent = this;
+    Name->setParents();
+  }
+
+  void BindPattern::setParents() {
+    Name->Parent = this;
+  }
+
+  void ReferenceExpression::setParents() {
+    Name->Parent = this;
+  }
+
+  void ConstantExpression::setParents() {
+    Token->Parent = this;
+  }
+
+  void CallExpression::setParents() {
+    Function->Parent = this;
+    Function->setParents();
+    for (auto Arg: Args) {
+      Arg->Parent = this;
+      Arg->setParents();
+    }
+  }
+
+  void InfixExpression::setParents() {
+    LHS->Parent = this;
+    LHS->setParents();
+    Operator->Parent = this;
+    RHS->Parent = this;
+    RHS->setParents();
+  }
+
+  void UnaryExpression::setParents() {
+    Operator->Parent = this;
+    Argument->Parent = this;
+    Argument->setParents();
+  }
+
+  void ExpressionStatement::setParents() {
+    Expression->Parent = this;
+    Expression->setParents();
+  }
+
+  void ReturnStatement::setParents() {
+    ReturnKeyword->Parent = this;
+    Expression->Parent = this;
+    Expression->setParents();
+  }
+
+  void TypeAssert::setParents() {
+    Colon->Parent = this;
+    TypeExpression->Parent = this;
+    TypeExpression->setParents();
+  }
+
+  void LetBlockBody::setParents() {
+    BlockStart->Parent = this;
+    for (auto Element: Elements) {
+      Element->Parent = this;
+      Element->setParents();
+    }
+  }
+
+  void LetExprBody::setParents() {
+    Equals->Parent = this;
+    Expression->Parent = this;
+    Expression->setParents();
+  }
+
+  void Param::setParents() {
+    Pattern->Parent = this;
+    Pattern->setParents();
+    if (TypeAssert) {
+      TypeAssert->Parent = this;
+      TypeAssert->setParents();
+    }
+  }
+
+  void LetDeclaration::setParents() {
+    if (PubKeyword) {
+      PubKeyword->Parent = this;
+    }
+    LetKeyword->Parent = this;
+    if (MutKeyword) {
+      MutKeyword->Parent = this;
+    }
+    Pattern->Parent = this;
+    Pattern->setParents();
+    for (auto Param: Params) {
+      Param->Parent = this;
+      Param->setParents();
+    }
+    if (TypeAssert) {
+      TypeAssert->Parent = this;
+      TypeAssert->setParents();
+    }
+    if (Body) {
+      Body->Parent = this;
+      Body->setParents();
+    }
+  }
+
+  void StructDeclField::setParents() {
+    Name->Parent = this;
+    Colon->Parent = this;
+    TypeExpression->Parent = this;
+    TypeExpression->setParents();
+  }
+
+  void StructDecl::setParents() {
+    StructKeyword->Parent = this;
+    Name->Parent = this;
+    BlockStart->Parent = this;
+    for (auto Field: Fields) {
+      Field->Parent = this;
+      Field->setParents();
+    }
+  }
+
+  void SourceFile::setParents() {
+    for (auto Element: Elements) {
+      Element->Parent = this;
+      Element->setParents();
+    }
+  }
+
+  Node::~Node() {
+  }
 
   Token::~Token() {
   }
@@ -180,7 +339,7 @@ namespace bolt {
     if (PubKeyword) {
       PubKeyword->unref();
     }
-    LetKeywod->unref();
+    LetKeyword->unref();
     if (MutKeyword) {
       MutKeyword->unref();
     }
@@ -205,7 +364,7 @@ namespace bolt {
   StructDecl::~StructDecl() {
     StructKeyword->unref();
     Name->unref();
-    Dot->unref();
+    BlockStart->unref();
     for (auto& Element: Fields){
       Element->unref();
     }
@@ -217,6 +376,189 @@ namespace bolt {
     }
   }
 
+  Token* QualifiedName::getFirstToken() {
+    if (ModulePath.size()) {
+      return ModulePath.front();
+    }
+    return Name;
+  }
+
+  Token* QualifiedName::getLastToken() {
+    return Name;
+  }
+
+  Token* ReferenceTypeExpression::getFirstToken() {
+    return Name->getFirstToken();
+  }
+
+  Token* ReferenceTypeExpression::getLastToken() {
+    return Name->getFirstToken();
+  }
+
+  Token* BindPattern::getFirstToken() {
+    return Name;
+  }
+
+  Token* BindPattern::getLastToken() {
+    return Name;
+  }
+
+  Token* ReferenceExpression::getFirstToken() {
+    return Name->getFirstToken();
+  }
+
+  Token* ReferenceExpression::getLastToken() {
+    return Name->getLastToken();
+  }
+
+  Token* ConstantExpression::getFirstToken() {
+    return Token;
+  }
+
+  Token* ConstantExpression::getLastToken() {
+    return Token;
+  }
+
+  Token* CallExpression::getFirstToken() {
+    return Function->getFirstToken();
+  }
+
+  Token* CallExpression::getLastToken() {
+    if (Args.size()) {
+      return Args.back()->getLastToken();
+    }
+    return Function->getLastToken();
+  }
+
+  Token* InfixExpression::getFirstToken() {
+    return LHS->getFirstToken();
+  }
+
+  Token* InfixExpression::getLastToken() {
+    return RHS->getLastToken();
+  }
+
+  Token* UnaryExpression::getFirstToken() {
+    return Operator;
+  }
+
+  Token* UnaryExpression::getLastToken() {
+    return Argument->getLastToken();
+  }
+  
+  Token* ExpressionStatement::getFirstToken() {
+    return Expression->getFirstToken();
+  }
+
+  Token* ExpressionStatement::getLastToken() {
+    return Expression->getLastToken();
+  }
+
+  Token* ReturnStatement::getFirstToken() {
+    return ReturnKeyword;
+  }
+
+  Token* ReturnStatement::getLastToken() {
+    if (Expression) {
+      return Expression->getLastToken();
+    }
+    return ReturnKeyword;
+  }
+
+  Token* TypeAssert::getFirstToken() {
+    return Colon;
+  }
+
+  Token* TypeAssert::getLastToken() {
+    return TypeExpression->getLastToken();
+  }
+
+  Token* Param::getFirstToken() {
+    return Pattern->getFirstToken();
+  }
+
+  Token* Param::getLastToken() {
+    if (TypeAssert) {
+      return TypeAssert->getLastToken();
+    }
+    return Pattern->getLastToken();
+  }
+
+  Token* LetBlockBody::getFirstToken() {
+    return BlockStart;
+  }
+
+  Token* LetBlockBody::getLastToken() {
+    if (Elements.size()) {
+      return Elements.back()->getLastToken();
+    }
+    return BlockStart;
+  }
+
+  Token* LetExprBody::getFirstToken() {
+    return Equals;
+  }
+
+  Token* LetExprBody::getLastToken() {
+    return Expression->getLastToken();
+  }
+
+  Token* LetDeclaration::getFirstToken() {
+    if (PubKeyword) {
+      return PubKeyword;
+    }
+    return LetKeyword;
+  }
+
+  Token* LetDeclaration::getLastToken() {
+    if (Body) {
+      return Body->getLastToken();
+    }
+    if (TypeAssert) {
+      return TypeAssert->getLastToken();
+    }
+    if (Params.size()) {
+      return Params.back()->getLastToken();
+    }
+    return Pattern->getLastToken();
+  }
+
+  Token* StructDeclField::getFirstToken() {
+    return Name;
+  }
+
+  Token* StructDeclField::getLastToken() {
+    return TypeExpression->getLastToken();
+  }
+
+  Token* StructDecl::getFirstToken() {
+    if (PubKeyword) {
+      return PubKeyword;
+    }
+    return StructKeyword;
+  }
+
+  Token* StructDecl::getLastToken() {
+    if (Fields.size()) {
+      Fields.back()->getLastToken();
+    }
+    return BlockStart;
+  }
+
+  Token* SourceFile::getFirstToken() {
+    if (Elements.size()) {
+      return Elements.front()->getFirstToken();
+    }
+    return nullptr;
+  }
+
+  Token* SourceFile::getLastToken() {
+    if (Elements.size()) {
+      return Elements.back()->getLastToken();
+    }
+    return nullptr;
+  }
+
   std::string Equals::getText() const {
     return "=";
   }
diff --git a/src/Checker.cc b/src/Checker.cc
index 32b58fc70..1bc0e80e3 100644
--- a/src/Checker.cc
+++ b/src/Checker.cc
@@ -181,9 +181,10 @@ namespace bolt {
       case NodeType::ReferenceExpression:
       {
         auto Y = static_cast<ReferenceExpression*>(X);
-        auto Scm = Ctx.Env.lookup(Y->Name->Text);
+        ZEN_ASSERT(Y->Name->ModulePath.empty());
+        auto Scm = Ctx.Env.lookup(Y->Name->Name->Text);
         if (Scm == nullptr) {
-          DE.add<BindingNotFoundDiagnostic>(Y->Name->Text, Y->Name);
+          DE.add<BindingNotFoundDiagnostic>(Y->Name->Name->Text, Y->Name);
           return new TAny();
         }
         return instantiate(*Scm);
diff --git a/src/Diagnostics.cc b/src/Diagnostics.cc
index c4fe3c6da..df1417bc9 100644
--- a/src/Diagnostics.cc
+++ b/src/Diagnostics.cc
@@ -1,5 +1,6 @@
 
 #include <sstream>
+#include <cmath>
 
 #include "zen/config.hpp"
 
@@ -31,6 +32,14 @@
 
 namespace bolt {
 
+  template<typename T>
+  T countDigits(T number) {
+    if (number == 0) {
+      return 1;
+    }
+    return std::ceil(std::log10(number+1));
+  }
+
   Diagnostic::Diagnostic(DiagnosticKind Kind):
     std::runtime_error("a compiler error occurred without being caught"), Kind(Kind) {}
 
@@ -122,10 +131,169 @@ namespace bolt {
     }
   }
 
-
   ConsoleDiagnostics::ConsoleDiagnostics(std::ostream& Out):
     Out(Out) {}
 
+  void ConsoleDiagnostics::setForegroundColor(Color C) {
+    if (EnableColors) {
+      switch (C) {
+        case Color::None:
+          break;
+        case Color::Black:
+          Out << ANSI_FG_BLACK;
+          break;
+        case Color::White:
+          Out << ANSI_FG_WHITE;
+          break;
+        case Color::Red:
+          Out << ANSI_FG_RED;
+          break;
+        case Color::Yellow:
+          Out << ANSI_FG_YELLOW;
+          break;
+        case Color::Green:
+          Out << ANSI_FG_GREEN;
+          break;
+        case Color::Blue:
+          Out << ANSI_FG_BLUE;
+          break;
+        case Color::Cyan:
+          Out << ANSI_FG_CYAN;
+          break;
+        case Color::Magenta:
+          Out << ANSI_FG_MAGENTA;
+          break;
+      }
+    }
+  }
+
+
+  void ConsoleDiagnostics::setBackgroundColor(Color C) {
+    if (EnableColors) {
+      switch (C) {
+        case Color::None:
+          break;
+        case Color::Black:
+          Out << ANSI_BG_BLACK;
+          break;
+        case Color::White:
+          Out << ANSI_BG_WHITE;
+          break;
+        case Color::Red:
+          Out << ANSI_BG_RED;
+          break;
+        case Color::Yellow:
+          Out << ANSI_BG_YELLOW;
+          break;
+        case Color::Green:
+          Out << ANSI_BG_GREEN;
+          break;
+        case Color::Blue:
+          Out << ANSI_BG_BLUE;
+          break;
+        case Color::Cyan:
+          Out << ANSI_BG_CYAN;
+          break;
+        case Color::Magenta:
+          Out << ANSI_BG_MAGENTA;
+          break;
+      }
+    }
+  }
+
+  void ConsoleDiagnostics::resetStyles() {
+    if (EnableColors) {
+      Out << ANSI_RESET;
+    }
+  }
+
+  void ConsoleDiagnostics::writeGutter(
+    std::size_t GutterWidth,
+    std::size_t Line
+  ) {
+    auto LineNumberDigitCount = countDigits(Line);
+    auto LeadingSpaces = GutterWidth - LineNumberDigitCount;
+    Out << "  ";
+    setForegroundColor(Color::Black);
+    setBackgroundColor(Color::White);
+    for (std::size_t i = 0; i < LeadingSpaces; i++) {
+      Out << ' ';
+    }
+    Out << Line;
+    resetStyles();
+    Out << " ";
+  }
+
+  void ConsoleDiagnostics::writeHighlight(
+    std::size_t GutterWidth,
+    TextRange Range,
+    Color HighlightColor,
+    std::size_t Line,
+    std::size_t LineLength
+  ) {
+    if (Line < Range.Start.Line || Range.End.Line < Line) {
+      return;
+    }
+    Out << "  ";
+    setBackgroundColor(Color::White);
+    for (std::size_t i = 0; i < GutterWidth; i++) {
+      Out << ' ';
+    }
+    resetStyles();
+    Out << ' ';
+    std::size_t start_column = Range.Start.Line == Line ? Range.Start.Column : 1;
+    std::size_t end_column = Range.End.Line == Line ? Range.End.Column : LineLength+1;
+    for (std::size_t i = 1; i < start_column; i++) {
+      Out << ' ';
+    }
+    setForegroundColor(HighlightColor);
+    for (std::size_t i = start_column; i < end_column; i++) {
+      Out << '~';
+    }
+    resetStyles();
+    Out << '\n';
+  }
+
+ void ConsoleDiagnostics::writeExcerpt(
+    TextFile& File,
+    TextRange ToPrint,
+    TextRange ToHighlight,
+    Color HighlightColor
+  ) {
+
+    auto Text = File.getText();
+    auto StartPos = ToPrint.Start;
+    auto EndPos = ToPrint.End;
+    auto StartLine = StartPos.Line-1 > ExcerptLinesPre ? StartPos.Line - ExcerptLinesPost : 1;
+    auto StartOffset = File.getStartOffset(StartLine);
+    auto EndLine = std::min(File.getLineCount(), EndPos.Line + ExcerptLinesPost);
+    auto EndOffset = File.getStartOffset(EndLine+1);
+    auto GutterWidth = std::max<std::size_t>(2, countDigits(EndLine+1));
+    auto HighlightStart = ToHighlight.Start;
+    auto HighlightEnd = ToHighlight.End;
+    auto HighlightRange = TextRange { HighlightStart, HighlightEnd };
+
+    std::size_t CurrColumn = 1;
+    std::size_t CurrLine = StartLine;
+    writeGutter(GutterWidth, CurrLine);
+    for (std::size_t i = StartOffset; i < EndOffset; i++) {
+      auto C = Text[i];
+      Out << C;
+      if (C == '\n') {
+        writeHighlight(GutterWidth, HighlightRange, HighlightColor, CurrLine, CurrColumn);
+        if (CurrLine == EndLine && C == '\n') {
+          break;
+        }
+        CurrLine++;
+        writeGutter(GutterWidth, CurrLine);
+        CurrColumn = 1;
+      } else {
+        CurrColumn++;
+      }
+    }
+
+  }
+
   void ConsoleDiagnostics::addDiagnostic(const Diagnostic& D) {
 
     switch (D.getKind()) {
@@ -163,6 +331,7 @@ namespace bolt {
             break;
         }
         Out << " but instead got '" << E.Actual->getText() << "'\n";
+        writeExcerpt(E.Actual->getSourceFile()->getTextFile(), E.Actual->getRange(), E.Actual->getRange(), Color::Red);
         break;
       }
 
diff --git a/src/Parser.cc b/src/Parser.cc
index baf426aeb..08615b7af 100644
--- a/src/Parser.cc
+++ b/src/Parser.cc
@@ -34,8 +34,8 @@ namespace bolt {
     Mapping.emplace(Name, OperatorInfo { Precedence, Flags });
   }
 
-  Parser::Parser(Stream<Token*>& S):
-    Tokens(S) {
+  Parser::Parser(TextFile& File, Stream<Token*>& S):
+    File(File), Tokens(S) {
       ExprOperators.add("**", OperatorFlags_InfixR, 10);
       ExprOperators.add("*", OperatorFlags_InfixL, 5);
       ExprOperators.add("/", OperatorFlags_InfixL, 5);
@@ -120,8 +120,10 @@ namespace bolt {
     auto T0 = Tokens.peek();
     switch (T0->Type) {
       case NodeType::Identifier:
-        Tokens.get();
-        return new ReferenceExpression(static_cast<Identifier*>(T0));
+      {
+        auto Name = parseQualifiedName();
+        return new ReferenceExpression(Name);
+      }
       case NodeType::IntegerLiteral:
       case NodeType::StringLiteral:
         Tokens.get();
@@ -320,7 +322,7 @@ after_params:
       }
       Elements.push_back(parseSourceElement());
     }
-    return new SourceFile(Elements);
+    return new SourceFile(File, Elements);
   }
 
 }
diff --git a/src/Text.cc b/src/Text.cc
index 17b2f05ba..ce1d0233e 100644
--- a/src/Text.cc
+++ b/src/Text.cc
@@ -6,7 +6,7 @@
 
 namespace bolt {
 
-  TextFile::TextFile(ByteString Path, ByteString Text):
+  TextFile::TextFile(ByteString Path, String Text):
     Path(Path), Text(Text) {
       LineOffsets.push_back(0);
       for (size_t I = 0; I < Text.size(); I++) {
@@ -18,6 +18,10 @@ namespace bolt {
       LineOffsets.push_back(Text.size());
     }
 
+  size_t TextFile::getLineCount() const {
+    return LineOffsets.size();
+  }
+
   size_t TextFile::getStartOffset(size_t Line) {
     return LineOffsets[Line-1];
   }
@@ -42,7 +46,7 @@ namespace bolt {
     return Path;
   }
 
-  ByteString TextFile::getText() const {
+  String TextFile::getText() const {
     return Text;
   }
 
diff --git a/src/main.cc b/src/main.cc
index 652eae794..1ba875f52 100644
--- a/src/main.cc
+++ b/src/main.cc
@@ -39,10 +39,11 @@ int main(int argc, const char* argv[]) {
   ConsoleDiagnostics DE;
 
   auto Text = readFile(argv[1]);
+  TextFile File { argv[1], Text };
   VectorStream<String> Chars(Text, EOF);
   Scanner S(Chars);
   Punctuator PT(S);
-  Parser P(PT);
+  Parser P(File, PT);
 
   SourceFile* SF; 
 
@@ -56,6 +57,8 @@ int main(int argc, const char* argv[]) {
   SF = P.parseSourceFile();
 #endif
 
+  SF->setParents();
+
   Checker TheChecker { DE };
   TheChecker.check(SF);