diff --git a/examples/hello.v b/examples/hello.v
deleted file mode 100644
index 46cc8fd..0000000
--- a/examples/hello.v
+++ /dev/null
@@ -1,3 +0,0 @@
-fn main() {
-	println("hello world!");
-}
diff --git a/src/ast.zig b/src/ast.zig
index 4de4f03..c9d44e8 100644
--- a/src/ast.zig
+++ b/src/ast.zig
@@ -1,25 +1,103 @@
-const std = @import("std");
 const tokens = @import("tokens.zig");
 const Token = tokens.Token;
 
-pub const NodeList = std.ArrayList(*Node);
-
-pub const NodeType = enum {
-    Root,
-    FnDecl,
+pub const ExprType = enum {
+    Unary,
+    Binary,
+    Grouping,
+    Number,
+    Bool,
+    Nil,
+    String,
 };
 
-pub const FnDecl = struct {
-    func_name: []const u8,
+pub const Expr = union(ExprType) {
+    Unary: UnaryExpr,
+    Binary: BinaryExpr,
+    Grouping: Grouping,
+    Number: Number,
+    Bool: Bool,
+    Nil: Nil,
+    String: String,
 };
 
-pub const Node = union(NodeType) {
-    Root: NodeList,
-    FnDecl: FnDecl,
+pub const UnaryExpr = struct {
+    operator: Token,
+    right: *Expr,
 };
 
-pub fn mkRoot(allocator: *std.mem.Allocator) !*Node {
-    var node = try allocator.create(Node);
-    node.* = Node{ .Root = NodeList.init(allocator) };
-    return node;
+pub fn mkUnary(operator: Token, right: *Expr) Expr {
+    return Expr{
+        .Unary = UnaryExpr{
+            .operator = operator,
+            .right = right,
+        },
+    };
 }
+
+pub const BinaryExpr = struct {
+    left: *Expr,
+    operator: Token,
+    right: *Expr,
+};
+
+pub fn mkBinary(left: *Expr, operator: Token, right: *Expr) Expr {
+    return Expr{
+        .Binary = BinaryExpr{
+            .left = left,
+            .operator = operator,
+            .right = right,
+        },
+    };
+}
+
+pub const Grouping = struct {
+    expression: *Expr,
+};
+
+pub fn mkGrouping(expression: *Expr) Expr {
+    return Expr{
+        .Grouping = Grouping{
+            .expression = expression,
+        },
+    };
+}
+
+/// Represents the default number literals in V.
+pub const NumberType = enum {
+    Integer32,
+    Integer64,
+    Unsigned32,
+    Unsigned64,
+    Float32,
+    Float64,
+};
+
+/// "translation" of V number types to Zig number types for nicer
+/// representation.
+pub const Number = union(NumberType) {
+    Integer32: i32,
+    Integer64: i64,
+    Unsigned32: u32,
+    Unsigned64: u64,
+    Float32: f32,
+    Float64: f64,
+};
+
+pub fn mkNum(comptime T: type, num: T) Expr {
+    var expr = switch (T) {
+        i32 => Expr{ .Number = Number{ .Integer32 = num } },
+        i64 => Expr{ .Number = Number{ .Integer64 = num } },
+        u32 => Expr{ .Number = Number{ .Unsigned32 = num } },
+        u64 => Expr{ .Number = Number{ .Unsigned64 = num } },
+        f32 => Expr{ .Number = Number{ .Float32 = num } },
+        f64 => Expr{ .Number = Number{ .Float64 = num } },
+        else => unreachable,
+    };
+
+    return expr;
+}
+
+pub const Bool = bool;
+pub const Nil = void;
+pub const String = []u8;
diff --git a/src/ast_printer.zig b/src/ast_printer.zig
new file mode 100644
index 0000000..ae1a9b7
--- /dev/null
+++ b/src/ast_printer.zig
@@ -0,0 +1,32 @@
+const std = @import("std");
+const ast = @import("ast.zig");
+
+fn parenthesize(name: []const u8, exprs: []*ast.Expr) void {
+    std.debug.warn("({}", name);
+
+    for (exprs) |expr| {
+        std.debug.warn(" ");
+        printAst(expr);
+    }
+
+    std.debug.warn(")");
+}
+
+pub fn printAst(ast_expr: *ast.Expr) void {
+    switch (ast_expr.*) {
+        .Binary => |expr| parenthesize(expr.operator.lexeme, &[]*ast.Expr{ expr.left, expr.right }),
+        .Grouping => |expr| parenthesize("group", &[]*ast.Expr{expr.expression}),
+        .Unary => |expr| parenthesize(expr.operator.lexeme, &[]*ast.Expr{expr.right}),
+        .Number => |ast_num| {
+            switch (ast_num) {
+                .Integer32 => |num| std.debug.warn("{}", num),
+                .Integer64 => |num| std.debug.warn("{}", num),
+                .Unsigned32 => |num| std.debug.warn("{}", num),
+                .Unsigned64 => |num| std.debug.warn("{}", num),
+                .Float32 => |num| std.debug.warn("{}", num),
+                .Float64 => |num| std.debug.warn("{}", num),
+            }
+        },
+        else => unreachable,
+    }
+}
diff --git a/src/main.zig b/src/main.zig
index bc07abc..96c4c58 100644
--- a/src/main.zig
+++ b/src/main.zig
@@ -67,7 +67,8 @@ fn runPrompt(allocator: *Allocator) !void {
 }
 
 pub fn main() anyerror!void {
-    var arena = std.heap.ArenaAllocator.init(std.heap.direct_allocator);
+    var da = std.heap.DirectAllocator.init();
+    var arena = std.heap.ArenaAllocator.init(&da.allocator);
     defer arena.deinit();
     var allocator = &arena.allocator;
 
diff --git a/src/parser.zig b/src/parser.zig
index e43588e..2e84369 100644
--- a/src/parser.zig
+++ b/src/parser.zig
@@ -10,7 +10,8 @@ const Scanner = scanners.Scanner;
 const Token = tokens.Token;
 const TokenType = tokens.TokenType;
 const Result = main.Result;
-const Node = ast.Node;
+
+const Expr = ast.Expr;
 
 pub const Parser = struct {
     allocator: *Allocator,
@@ -23,7 +24,7 @@ pub const Parser = struct {
         return Parser{ .allocator = allocator, .scanner = scanner };
     }
 
-    fn doError(self: *Parser, comptime fmt: []const u8, args: ...) Result!void {
+    fn doError(self: *Parser, comptime fmt: []const u8, args: ...) !void {
         std.debug.warn("parser error at line {}\n\t", self.scanner.line);
         std.debug.warn(fmt, args);
         std.debug.warn("\n");
@@ -49,6 +50,20 @@ pub const Parser = struct {
         return Result.CompileError;
     }
 
+    fn synchronize(self: *Parser) void {
+        _ = self.advance();
+        while (!self.isAtEnd()) {
+            if (self.previous().ttype == .Semicolon) return;
+
+            switch (self.peek().ttype) {
+                .Struct, .Fn, .For, .If, .Return => return,
+                else => {},
+            }
+
+            _ = self.advance();
+        }
+    }
+
     fn isAtEnd(self: *Parser) bool {
         return self.peek().ttype == .EOF;
     }
@@ -90,50 +105,150 @@ pub const Parser = struct {
         return Result.CompileError;
     }
 
-    fn mkFnDecl(self: *Parser, name: []const u8) !*ast.Node {
-        var node = try self.allocator.create(Node.FnDecl);
-        node.* = Node.FnDecl{ .name = name };
-        return node;
-    }
+    fn equality(self: *Parser) !Expr {
+        var expr = try self.comparison();
 
-    fn functionDecl(self: *Parser) !*ast.Node {
-        // get the name
-        var name = try self.consume(.Identifier, "expected function name");
-        return try self.mkFnDecl(name);
-    }
+        while (self.match(&[]TokenType{ TokenType.BangEqual, TokenType.EqualEqual })) {
+            var operator = self.previous();
+            var right = try self.comparison();
 
-    fn processToken(self: *Parser, token: Token) Result!ast.Node {
-        switch (token.ttype) {
-            //.Fn => try self.functionDecl(),
-            else => blk: {
-                try self.doError("TODO handle {}\n", token.ttype);
-                return Result.CompileError;
-            },
+            expr = ast.mkBinary(&expr, operator, &right);
         }
+
+        return expr;
     }
 
-    pub fn parse(self: *Parser) !*ast.Node {
+    fn comparison(self: *Parser) !Expr {
+        var expr = try self.addition();
+
+        while (self.match(&[]TokenType{
+            TokenType.Greater,
+            TokenType.GreaterEqual,
+            TokenType.Less,
+            TokenType.LessEqual,
+        })) {
+            var operator = self.previous();
+            var right = try self.addition();
+            expr = ast.mkBinary(&expr, operator, &right);
+        }
+
+        return expr;
+    }
+
+    fn addition(self: *Parser) !Expr {
+        var expr = try self.multiplication();
+
+        while (self.match(&[]TokenType{ TokenType.Minus, TokenType.Plus })) {
+            var operator = self.previous();
+            var right = try self.multiplication();
+            expr = ast.mkBinary(&expr, operator, &right);
+        }
+
+        return expr;
+    }
+
+    fn multiplication(self: *Parser) anyerror!Expr {
+        var expr = try self.unary();
+
+        while (self.match(&[]TokenType{ TokenType.Slash, TokenType.Star })) {
+            var operator = self.previous();
+            var right = try self.unary();
+            expr = ast.mkBinary(&expr, operator, &right);
+        }
+
+        return expr;
+    }
+
+    fn unary(self: *Parser) anyerror!Expr {
+        if (self.match(&[]TokenType{ TokenType.Bang, TokenType.Minus })) {
+            var operator = self.previous();
+            var right = try self.unary();
+            return ast.mkUnary(operator, &right);
+        }
+
+        return try self.primary();
+    }
+
+    fn doInt(self: *Parser) !Expr {
+        var token = self.previous();
+
+        // try to parse it as an i32 first, if that fails, do i64.
+
+        var num_32 = std.fmt.parseInt(i32, token.lexeme, 10) catch |pi_err| {
+            if (pi_err == error.Overflow) {
+                var num_64 = std.fmt.parseInt(i64, token.lexeme, 10) catch |pi_err2| {
+                    if (pi_err2 == error.Overflow) {
+                        try self.tokenError(token, "Failed to parse number: overflow");
+                        return Result.CompileError;
+                    } else {
+                        return pi_err2;
+                    }
+                };
+
+                return ast.mkNum(i64, num_64);
+            } else {
+                return pi_err;
+            }
+        };
+
+        return ast.mkNum(i32, num_32);
+    }
+
+    fn primary(self: *Parser) !Expr {
+        if (self.matchSingle(TokenType.False)) return ast.Expr{ .Bool = false };
+        if (self.matchSingle(TokenType.True)) return ast.Expr{ .Bool = true };
+        if (self.matchSingle(TokenType.None)) return ast.Expr{ .Nil = {} };
+
+        if (self.matchSingle(TokenType.Integer)) {
+            return try self.doInt();
+        }
+
+        if (self.matchSingle(TokenType.String)) {
+            var lexeme = self.previous().lexeme;
+            var slice = try self.allocator.alloc(u8, lexeme.len);
+            std.mem.copy(u8, slice, lexeme);
+
+            return ast.Expr{ .String = slice };
+        }
+
+        if (self.matchSingle(TokenType.LeftParen)) {
+            var expr = try self.expression();
+            _ = try self.consume(.RightParen, "Expect ')' after expression");
+
+            return ast.mkGrouping(&expr);
+        }
+
+        try self.tokenError(self.peek(), "Expect expression");
+        return Result.CompileError;
+    }
+
+    fn expression(self: *Parser) !Expr {
+        return try self.equality();
+    }
+
+    pub fn parse(self: *Parser) !?*Expr {
         self.tokens = try self.allocator.alloc(Token, 0);
         var i: usize = 0;
-        var root = try ast.mkRoot(self.allocator);
 
         while (true) {
             var tok_opt = try self.scanner.nextToken();
-
             if (tok_opt) |token| {
                 self.tokens = try self.allocator.realloc(self.tokens, i + 1);
                 self.tokens[i] = token;
                 i += 1;
 
                 if (token.ttype == .EOF) break;
-
-                var node = try self.processToken(token);
-                try root.Root.append(&node);
-            } else {
-                continue;
             }
         }
 
-        return root;
+        std.debug.warn("{} tokens\n", i);
+
+        //return Expr{ .Number = ast.Number{ .Integer32 = 69 } };
+        //return self.root;
+        var expr = self.expression() catch |parse_err| {
+            return null;
+        };
+
+        return &expr;
     }
 };
diff --git a/src/runner.zig b/src/runner.zig
index e0f6493..c33eef5 100644
--- a/src/runner.zig
+++ b/src/runner.zig
@@ -44,12 +44,22 @@ pub const Runner = struct {
 
         scanner = scanners.Scanner.init(self.allocator, code);
         var parser = Parser.init(self.allocator, &scanner);
-        var root = try parser.parse();
+        var expr_opt = try parser.parse();
 
-        var it = root.Root.iterator();
+        //var expr = ast.mkBinary(
+        //    &ast.mkUnary(
+        //        tokens.Token{ .ttype = .Minus, .lexeme = "-", .line = 1 },
+        //        &ast.mkNum(i32, 123),
+        //    ),
+        //    tokens.Token{ .ttype = .Star, .lexeme = "*", .line = 1 },
+        //    &ast.mkGrouping(&ast.mkNum(f32, 45.67)),
+        //);
 
-        while (it.next()) |node| {
-            std.debug.warn("{}\n", node.*);
+        if (expr_opt) |expr_ptr| {
+            printer.printAst(expr_ptr);
+            std.debug.warn("\n");
+        } else {
+            return Result.CompileError;
         }
 
         return Result.Ok;
diff --git a/src/scanner.zig b/src/scanner.zig
index 491f1f2..0a632ee 100644
--- a/src/scanner.zig
+++ b/src/scanner.zig
@@ -24,7 +24,7 @@ fn isAlphaNumeric(char: u8) bool {
     return isAlpha(char) or isDigit(char);
 }
 
-const keywords = [_][]const u8{
+const keywords = [][]const u8{
     "break",
     "const",
     "continue",
@@ -51,7 +51,7 @@ const keywords = [_][]const u8{
     "None",
 };
 
-const keyword_ttypes = [_]TokenType{
+const keyword_ttypes = []TokenType{
     .Break,
     .Const,
     .Continue,
@@ -186,17 +186,35 @@ pub const Scanner = struct {
 
     /// Peek at the next character in the scanner
     fn peekNext(self: *Scanner) u8 {
-        if (self.current + 1 > self.source.len) return 0;
+        if (self.current > self.source.len) return 0;
         return self.source[self.current];
     }
 
+    /// Skip all whitespace, but increments Scanner.line when finding a newline.
+    fn skipWhitespace(self: *Scanner) void {
+        while (true) {
+            var c = self.peek();
+
+            switch (c) {
+                ' ', '\r', '\t' => blk: {
+                    _ = self.advance();
+                },
+                '\n' => blk: {
+                    self.line += 1;
+                    _ = self.advance();
+                },
+                else => return,
+            }
+        }
+    }
+
     /// Consume a number.
     /// Returns either an Integer or a Float token. Proper typing
     /// of the number (i32 i64 u32 u64 f32 f64) are for the parser.
     fn doNumber(self: *Scanner) Token {
         var ttype = TokenType.Integer;
 
-        while (isDigit(self.peekNext())) {
+        while (isDigit(self.peek())) {
             _ = self.advance();
         }
 
@@ -261,6 +279,7 @@ pub const Scanner = struct {
     }
 
     pub fn nextToken(self: *Scanner) !?Token {
+        self.skipWhitespace();
         self.start = self.current;
 
         if (self.isAtEnd()) return self.makeToken(TokenType.EOF);
@@ -323,12 +342,6 @@ pub const Scanner = struct {
             '\'' => try self.doString('\''),
             '"' => try self.doString('"'),
 
-            ' ', '\r', '\t' => null,
-            '\n' => blk: {
-                self.line += 1;
-                break :blk null;
-            },
-
             else => return ScannerError.Unexpected,
         };