compiler/Compiler/Generator.cs

@@ -71,6 +71,9 @@ public sealed class Generator(List<NodeDefinition> nodes)
             case NodeStatementAssignment statement:
                 EmitStatementAssignment(statement);
                 break;
+            case NodeStatementIf statement:
+                EmitStatementIf(statement);
+                break;
             default:
                 throw new ArgumentOutOfRangeException(nameof(node), node, null);
         }
@@ -114,6 +117,36 @@ public sealed class Generator(List<NodeDefinition> nodes)
         writer.WriteLine($"{target} = {value};");
     }
 
+    private void EmitStatementIf(NodeStatementIf statement)
+    {
+        var condition = EmitExpression(statement.Condition);
+        writer.WriteLine($"if ({condition})");
+        writer.WriteLine("{");
+        using (writer.Indent())
+        {
+            EmitStatement(statement.ThenBlock);
+        }
+
+        writer.WriteLine("}");
+
+        if (statement.ElseBlock != null)
+        {
+            writer.Write("else");
+            if (statement.ElseBlock is NodeStatementIf)
+                writer.Write(" ");
+            else
+                writer.WriteLine();
+
+            writer.WriteLine("{");
+            using (writer.Indent())
+            {
+                EmitStatement(statement.ElseBlock);
+            }
+
+            writer.WriteLine("}");
+        }
+    }
+
     private string EmitExpression(NodeExpression node)
     {
         return node switch

compiler/Compiler/Parser.cs

@@ -80,6 +80,18 @@ public sealed class Parser(List<Token> tokens)
             return new NodeStatementVariableDeclaration(TokensFrom(startIndex), name, type, value);
         }
 
+        if (TryExpectKeyword(Keyword.If))
+        {
+            var condition = ParseExpression();
+            var thenBlock = ParseStatement();
+            NodeStatement? elseBlock = null;
+
+            if (TryExpectKeyword(Keyword.Else))
+                elseBlock = ParseStatement();
+
+            return new NodeStatementIf(TokensFrom(startIndex), condition, thenBlock, elseBlock);
+        }
+
         var target = ParseExpression();
 
         if (TryExpectSymbol(Symbol.OpenParen))
@@ -308,7 +320,7 @@ public sealed class Parser(List<Token> tokens)
 
 public abstract class Node(List<Token> tokens)
 {
-    public List<Token> Tokens = tokens;
+    public readonly List<Token> Tokens = tokens;
 }
 
 public abstract class NodeDefinition(List<Token> tokens) : Node(tokens);
@@ -358,6 +370,13 @@ internal class NodeStatementAssignment(List<Token> tokens, NodeExpression target
     public readonly NodeExpression Value = value;
 }
 
+internal class NodeStatementIf(List<Token> tokens, NodeExpression condition, NodeStatement thenBlock, NodeStatement? elseBlock) : NodeStatement(tokens)
+{
+    public readonly NodeExpression Condition = condition;
+    public readonly NodeStatement ThenBlock = thenBlock;
+    public readonly NodeStatement? ElseBlock = elseBlock;
+}
+
 public abstract class NodeExpression(List<Token> tokens) : Node(tokens);
 
 public sealed class NodeExpressionIntLiteral(List<Token> tokens, TokenIntLiteral value) : NodeExpression(tokens)

compiler/Compiler/Program.cs

@@ -4,6 +4,14 @@ const string contents = """
                         func main(): i32 {
                             let x: i32 = 23
                             x = 24
+                            
+                            if true {
+                                x = 49
+                            }
+                            else {
+                                x = 3
+                            }
+                            
                             do_something("test")
                             return x
                         }

compiler/Compiler/Tokenizer.cs

@@ -279,6 +279,7 @@ public sealed class Tokenizer(string contents)
                         "func" => new TokenKeyword(line, startColumn, column - startColumn, Keyword.Func),
                         "let" => new TokenKeyword(line, startColumn, column - startColumn, Keyword.Let),
                         "if" => new TokenKeyword(line, startColumn, column - startColumn, Keyword.If),
+                        "else" => new TokenKeyword(line, startColumn, column - startColumn, Keyword.Else),
                         "return" => new TokenKeyword(line, startColumn, column - startColumn, Keyword.Return),
                         "true" => new TokenBoolLiteral(line, startColumn, column - startColumn, true),
                         "false" => new TokenBoolLiteral(line, startColumn, column - startColumn, false),
@@ -398,6 +399,7 @@ public enum Keyword
     Func,
     Let,
     If,
+    Else,
     Return,
 }