diff --git a/src/ast/printer.rs b/src/ast/printer.rs
index 6a2ebb2..b56194e 100644
--- a/src/ast/printer.rs
+++ b/src/ast/printer.rs
@@ -12,105 +12,352 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 use std::borrow::BorrowMut;
-use std::error::Error;
 use std::io::Write;
 
-use crate::ast::walk::Walker;
 use crate::ast::*;
 
 // TODO(jwall): We really need a way to preserve comments for these.
 // Perhaps for code formatting we actually want to work on the token stream instead?
 
-pub struct Printer {
-    indent: u8,
-    curr_indent: u8,
-    w: Box<dyn Write>,
-    pub errs: Vec<Box<dyn Error>>,
+pub struct AstPrinter<W>
+where
+    W: Write,
+{
+    indent: usize,
+    curr_indent: usize,
+    w: W,
+    pub err: Option<std::io::Error>,
 }
 
-impl Printer {
-    pub fn new(indent: u8, w: Box<dyn Write>) -> Self {
-        Printer {
+impl<W> AstPrinter<W>
+where
+    W: Write,
+{
+    pub fn new(indent: usize, w: W) -> Self {
+        AstPrinter {
             indent: indent,
             curr_indent: 0,
             w: w,
-            errs: Vec::new(),
+            err: None,
         }
     }
 
-    pub fn render_list_def(&mut self, def: &ListDef) -> std::io::Result<()> {
-        panic!("Unimplemented");
-        Ok(())
-    }
-
-    pub fn render_tuple_def(&mut self, def: &Vec<(Token, Expression)>) -> std::io::Result<()> {
-        panic!("Unimplemented");
-        Ok(())
-    }
-
-    pub fn render_value(&mut self, v: &Value) {
-        // TODO
+    pub fn visit_token(&mut self, t: &Token) -> std::io::Result<()> {
         let w: &mut Write = self.w.borrow_mut();
-        let result = match v {
-            Value::Boolean(b) => write!(w, "{}", b),
-            Value::Empty(_) => write!(w, "NULL"),
-            // TODO(jwall): Should we maintain precision for floats?
-            Value::Float(f) => write!(w, "{}", f),
-            Value::Int(i) => write!(w, "{}", i),
-            // TODO(jwall): Make sure that we properly escape quotes here when rendering this?
-            Value::Str(s) => write!(w, "\"{}\"", s),
-            Value::Symbol(s) => write!(w, "{}", s),
-            Value::List(l) => self.render_list_def(l),
-            Value::Tuple(tpl) => self.render_tuple_def(&tpl.val),
+        // Do we care about line length?
+        match t.typ {
+            TokenType::BAREWORD | TokenType::BOOLEAN | TokenType::DIGIT => {
+                write!(w, "{}", t.fragment)?;
+            }
+            TokenType::EMPTY => {
+                write!(w, "NULL")?;
+            }
+            TokenType::PUNCT => {
+                // TODO(jwall): We need to identify the points at which we
+                // introduce new lines and new indentation scopes.
+            }
+            TokenType::COMMENT => {
+                // We need to track some state here probably.
+                // Do we leave comments untouched?
+            }
+            TokenType::PIPEQUOTE => {
+                // FIXME I think is supposed to be removed.
+            }
+            TokenType::QUOTED => {
+                w.write(&['"' as u8])?;
+                write!(w, "{}", Self::escape_quotes(&t.fragment))?;
+                w.write(&['"' as u8])?;
+            }
+            TokenType::WS => {
+                // TODO(jwall): Track some state around new lines here?
+            }
+            TokenType::END => {
+                // NOOP
+            }
         };
-        if let Err(e) = result {
-            self.errs.push(Box::new(e));
-        }
+        Ok(())
     }
 
-    fn render_expr(&mut self, expr: &Expression) {
+    fn make_indent(&self) -> String {
+        // TODO(jwall): This is probably inefficient but we'll improve it after
+        // we get it correct.
+        let indent: Vec<u8> = std::iter::repeat(' ' as u8)
+            .take(self.curr_indent)
+            .collect();
+        String::from_utf8_lossy(&indent).to_string()
+    }
+
+    fn render_list_def(&mut self, def: &ListDef) -> std::io::Result<()> {
+        write!(self.w, "[\n")?;
+        self.curr_indent += self.indent;
+        // If the element list is just 1 we might be able to collapse the tuple.
+        let indent = self.make_indent();
+        for e in def.elems.iter() {
+            // TODO(jwall): Now print out the elements
+            write!(self.w, "{}", indent)?;
+            self.render_expr(e)?;
+            write!(self.w, "\n")?;
+        }
+        self.curr_indent -= self.indent;
+        self.w.write(&[']' as u8])?;
+        Ok(())
+    }
+
+    fn render_tuple_def(&mut self, def: &Vec<(Token, Expression)>) -> std::io::Result<()> {
+        self.w.write(&['{' as u8])?;
+        // If the field list is just 1 we might be able to collapse the tuple.
+        self.curr_indent += self.indent;
+        let indent = self.make_indent();
+        for &(ref t, ref expr) in def.iter() {
+            write!(self.w, "{}", indent)?;
+            // TODO(jwall): Detect if there are strings and render as a quoted string.
+            write!(&mut self.w, "{} = ", t.fragment)?;
+            self.render_expr(expr)?;
+            write!(&mut self.w, ",")?;
+            write!(self.w, "\n")?;
+        }
+        self.w.write(&['}' as u8])?;
+        Ok(())
+    }
+
+    fn escape_quotes(s: &str) -> String {
+        let mut escaped = String::new();
+        for c in s.chars() {
+            if c == '"' {
+                escaped.push_str("\\\"");
+            } else if c == '\\' {
+                escaped.push_str("\\\\");
+            } else {
+                escaped.push(c);
+            }
+        }
+        escaped
+    }
+
+    pub fn render_value(&mut self, v: &Value) -> std::io::Result<()> {
+        match v {
+            Value::Boolean(b) => write!(self.w, "{}", if b.val { "true" } else { "false" })?,
+            Value::Empty(_) => write!(self.w, "NULL")?,
+            // TODO(jwall): We should maintain precision for floats?
+            Value::Float(f) => write!(self.w, "{}", f.val)?,
+            Value::Int(i) => write!(self.w, "{}", i.val)?,
+            Value::Str(s) => write!(self.w, "\"{}\"", Self::escape_quotes(&s.val))?,
+            Value::Symbol(s) => write!(self.w, "{}", s.val)?,
+            Value::List(l) => self.render_list_def(l)?,
+            Value::Tuple(tpl) => self.render_tuple_def(&tpl.val)?,
+        };
+        Ok(())
+    }
+
+    fn render_expr(&mut self, expr: &Expression) -> std::io::Result<()> {
         match expr {
-            Expression::Binary(_def) => {}
-            Expression::Call(_def) => {}
-            Expression::Copy(_def) => {}
-            Expression::Debug(_def) => {}
-            Expression::Fail(_def) => {}
-            Expression::Format(_def) => {}
-            Expression::Func(_def) => {}
-            Expression::FuncOp(_def) => {}
-            Expression::Grouped(_expr, _) => {}
-            Expression::Import(_def) => {}
-            Expression::Include(_def) => {}
-            Expression::Module(_def) => {}
-            Expression::Not(_def) => {}
-            Expression::Range(_def) => {}
-            Expression::Select(_def) => {}
-            Expression::Simple(_def) => {}
-        }
+            Expression::Binary(_def) => {
+                let op = match _def.kind {
+                    BinaryExprType::AND => " && ",
+                    BinaryExprType::OR => " || ",
+                    BinaryExprType::DOT => ".",
+                    BinaryExprType::Equal => " = ",
+                    BinaryExprType::NotEqual => " != ",
+                    BinaryExprType::GTEqual => " >= ",
+                    BinaryExprType::LTEqual => " <= ",
+                    BinaryExprType::GT => " > ",
+                    BinaryExprType::LT => " < ",
+                    BinaryExprType::Add => " + ",
+                    BinaryExprType::Sub => " - ",
+                    BinaryExprType::Mul => " * ",
+                    BinaryExprType::Div => " / ",
+                    BinaryExprType::Mod => " %% ",
+                    BinaryExprType::IN => " in ",
+                    BinaryExprType::IS => " is ",
+                    BinaryExprType::REMatch => " ~ ",
+                    BinaryExprType::NotREMatch => " !~ ",
+                };
+                self.render_expr(&_def.left)?;
+                self.w.write(op.as_bytes())?;
+                self.render_expr(&_def.right)?;
+            }
+            Expression::Call(_def) => {
+                self.render_value(&_def.funcref)?;
+                self.w.write("(".as_bytes())?;
+                self.curr_indent += self.indent;
+                let indent = self.make_indent();
+                for e in _def.arglist.iter() {
+                    self.w.write(indent.as_bytes())?;
+                    self.render_expr(e)?;
+                    self.w.write("\n".as_bytes())?;
+                }
+                self.curr_indent -= self.indent;
+                self.w.write("(".as_bytes())?;
+            }
+            Expression::Copy(_def) => {
+                self.render_value(&_def.selector)?;
+                self.render_tuple_def(&_def.fields)?;
+            }
+            Expression::Debug(_def) => {
+                self.w.write("TRACE ".as_bytes())?;
+                self.render_expr(&_def.expr)?;
+            }
+            Expression::Fail(_def) => {
+                self.w.write("fail ".as_bytes())?;
+                self.render_expr(&_def.message)?;
+            }
+            Expression::Format(_def) => {
+                self.w
+                    .write(Self::escape_quotes(&_def.template).as_bytes())?;
+                write!(self.w, " % ")?;
+                match _def.args {
+                    FormatArgs::Single(ref e) => {
+                        self.render_expr(e)?;
+                    }
+                    FormatArgs::List(ref es) => {
+                        self.w.write("(".as_bytes())?;
+                        self.curr_indent += self.indent;
+                        let indent = self.make_indent();
+                        for e in es.iter() {
+                            self.w.write(indent.as_bytes())?;
+                            self.render_expr(e)?;
+                            self.w.write("\n".as_bytes())?;
+                        }
+                        self.curr_indent -= self.indent;
+                        self.w.write(")".as_bytes())?;
+                    }
+                }
+            }
+            Expression::Func(_def) => {
+                self.w.write("func (".as_bytes())?;
+                for n in _def.argdefs.iter() {
+                    write!(self.w, "{}, ", n.val)?;
+                }
+                self.w.write(") => ".as_bytes())?;
+                self.render_expr(&_def.fields)?;
+            }
+            Expression::FuncOp(_def) => match _def {
+                FuncOpDef::Filter(_def) => {
+                    write!(self.w, "filter(")?;
+                    self.render_expr(&_def.func)?;
+                    write!(self.w, ", ")?;
+                    self.render_expr(&_def.target)?;
+                    write!(self.w, ")")?;
+                }
+                FuncOpDef::Reduce(_def) => {
+                    write!(self.w, "reduce(")?;
+                    self.render_expr(&_def.func)?;
+                    write!(self.w, ", ")?;
+                    self.render_expr(&_def.acc)?;
+                    write!(self.w, ", ")?;
+                    self.render_expr(&_def.target)?;
+                    write!(self.w, ")")?;
+                }
+                FuncOpDef::Map(_def) => {
+                    write!(self.w, "map(")?;
+                    self.render_expr(&_def.func)?;
+                    write!(self.w, ", ")?;
+                    self.render_expr(&_def.target)?;
+                    write!(self.w, ")")?;
+                }
+            },
+            Expression::Grouped(ref expr, _) => {
+                write!(self.w, "(")?;
+                self.render_expr(expr)?;
+                write!(self.w, ")")?;
+            }
+            Expression::Import(_def) => {
+                write!(
+                    self.w,
+                    "import \"{}\"",
+                    Self::escape_quotes(&_def.path.fragment)
+                )?;
+            }
+            Expression::Include(_def) => {
+                write!(
+                    self.w,
+                    "include {} \"{}\"",
+                    _def.typ.fragment,
+                    Self::escape_quotes(&_def.path.fragment)
+                )?;
+            }
+            Expression::Module(_def) => {
+                write!(self.w, "module ")?;
+                self.render_tuple_def(&_def.arg_set)?;
+                write!(self.w, " => ")?;
+                if let Some(ref e) = _def.out_expr {
+                    write!(self.w, "(")?;
+                    self.render_expr(e)?;
+                    write!(self.w, ") ")?;
+                }
+                write!(self.w, "{{")?;
+                self.curr_indent += self.indent;
+                let indent = self.make_indent();
+                for stmt in _def.statements.iter() {
+                    write!(self.w, "{}", indent)?;
+                    self.render_stmt(stmt)?;
+                }
+                self.curr_indent -= self.indent;
+                write!(self.w, "}}")?;
+            }
+            Expression::Not(_def) => {
+                write!(self.w, "not ")?;
+                self.render_expr(&_def.expr)?;
+            }
+            Expression::Range(_def) => {
+                self.render_expr(&_def.start)?;
+                write!(self.w, ":")?;
+                if let Some(ref e) = _def.step {
+                    write!(self.w, ":")?;
+                    self.render_expr(e)?;
+                }
+                self.render_expr(&_def.end)?;
+            }
+            Expression::Select(_def) => {
+                //
+                write!(self.w, "select ")?;
+                self.render_expr(&_def.val)?;
+                write!(self.w, ", ")?;
+                if let Some(ref e) = _def.default {
+                    self.render_expr(e)?;
+                    write!(self.w, ", ")?;
+                }
+                self.render_tuple_def(&_def.tuple)?;
+            }
+            Expression::Simple(ref _def) => {
+                self.render_value(_def)?;
+            }
+        };
+        Ok(())
     }
 
-    fn render_stmt(&mut self, stmt: &Statement) {
+    fn render_stmt(&mut self, stmt: &Statement) -> std::io::Result<()> {
+        // All statements start at the beginning of a line.
         match stmt {
-            Statement::Let(_def) => {}
-            Statement::Expression(_expr) => {}
-            Statement::Assert(_def) => {}
-            Statement::Output(_, _tok, _expr) => {}
-        }
+            Statement::Let(def) => {
+                write!(&mut self.w, "let {} = ", def.name.fragment)?;
+                self.render_expr(&def.value)?;
+            }
+            Statement::Expression(_expr) => {
+                self.render_expr(&_expr)?;
+                //
+            }
+            Statement::Assert(def) => {
+                write!(&mut self.w, "assert ")?;
+                self.render_expr(&def)?;
+                //
+            }
+            Statement::Output(_, _tok, _expr) => {
+                write!(&mut self.w, "out {} = ", _tok.fragment)?;
+                self.render_expr(&_expr)?;
+                //
+            }
+        };
+        write!(self.w, ";\n")?;
+        Ok(())
     }
 
     pub fn render(&mut self, stmts: Vec<&mut Statement>) {
-        self.walk_statement_list(stmts);
-    }
-}
-
-impl Walker for Printer {
-    fn visit_value(&mut self, val: &mut Value) {
-        self.render_value(val);
-    }
-    fn visit_expression(&mut self, expr: &mut Expression) {
-        self.render_expr(expr);
-    }
-    fn visit_statement(&mut self, stmt: &mut Statement) {
-        self.render_stmt(stmt);
+        for v in stmts {
+            if let Err(e) = self.render_stmt(v) {
+                self.err = Some(e);
+                return;
+            }
+        }
     }
 }
diff --git a/src/parse/mod.rs b/src/parse/mod.rs
index 4578022..96bec15 100644
--- a/src/parse/mod.rs
+++ b/src/parse/mod.rs
@@ -854,7 +854,7 @@ fn statement(i: SliceIter<Token>) -> Result<SliceIter<Token>, Statement> {
 
 /// Parses a LocatedSpan into a list of Statements or an `error::Error`.
 pub fn parse<'a>(input: OffsetStrIter<'a>) -> std::result::Result<Vec<Statement>, String> {
-    match tokenize(input.clone()) {
+    match tokenize(input.clone(), true) {
         Ok(tokenized) => {
             let mut out = Vec::new();
             let mut i_ = SliceIter::new(&tokenized);
diff --git a/src/tokenizer/mod.rs b/src/tokenizer/mod.rs
index b191fe7..07d5a74 100644
--- a/src/tokenizer/mod.rs
+++ b/src/tokenizer/mod.rs
@@ -452,7 +452,10 @@ fn token<'a>(input: OffsetStrIter<'a>) -> Result<OffsetStrIter<'a>, Token> {
 }
 
 /// Consumes an input OffsetStrIter and returns either a Vec<Token> or a error::Error.
-pub fn tokenize<'a>(input: OffsetStrIter<'a>) -> std::result::Result<Vec<Token>, String> {
+pub fn tokenize<'a>(
+    input: OffsetStrIter<'a>,
+    skip_comments: bool,
+) -> std::result::Result<Vec<Token>, String> {
     let mut out = Vec::new();
     let mut i = input.clone();
     loop {
@@ -486,7 +489,7 @@ pub fn tokenize<'a>(input: OffsetStrIter<'a>) -> std::result::Result<Vec<Token>,
             }
             Result::Complete(rest, tok) => {
                 i = rest;
-                if tok.typ == TokenType::COMMENT || tok.typ == TokenType::WS {
+                if (skip_comments && tok.typ == TokenType::COMMENT) || tok.typ == TokenType::WS {
                     // we skip comments and whitespace
                     continue;
                 }
diff --git a/src/tokenizer/test.rs b/src/tokenizer/test.rs
index 2458226..0ef757c 100644
--- a/src/tokenizer/test.rs
+++ b/src/tokenizer/test.rs
@@ -89,7 +89,7 @@ fn test_string_with_escaping() {
 #[test]
 fn test_tokenize_bareword_with_dash() {
     let input = OffsetStrIter::new("foo-bar ");
-    let result = tokenize(input.clone());
+    let result = tokenize(input.clone(), true);
     assert!(result.is_ok(), format!("result {:?} is not ok", result));
     if let Ok(toks) = result {
         assert_eq!(toks.len(), 2);
@@ -157,7 +157,7 @@ fn test_tokenize_one_of_each() {
         "map out filter assert let import func select as => [ ] { } ; = % / * \
          + - . ( ) , 1 . foo \"bar\" // comment\n ; true false == < > <= >= !=",
     );
-    let result = tokenize(input.clone());
+    let result = tokenize(input.clone(), true);
     assert!(result.is_ok(), format!("result {:?} is not ok", result));
     let v = result.unwrap();
     for (i, t) in v.iter().enumerate() {
@@ -170,7 +170,7 @@ fn test_tokenize_one_of_each() {
 #[test]
 fn test_parse_has_end() {
     let input = OffsetStrIter::new("foo");
-    let result = tokenize(input.clone());
+    let result = tokenize(input.clone(), true);
     assert!(result.is_ok());
     let v = result.unwrap();
     assert_eq!(v.len(), 2);