...

compiler/Compiler/Generator.cs

@@ -74,6 +74,9 @@ public sealed class Generator(List<NodeDefinition> nodes)
             case NodeStatementIf statement:
                 EmitStatementIf(statement);
                 break;
+            case NodeStatementWhile statement:
+                EmitStatementWhile(statement);
+                break;
             default:
                 throw new ArgumentOutOfRangeException(nameof(node), node, null);
         }
@@ -147,6 +150,18 @@ public sealed class Generator(List<NodeDefinition> nodes)
         }
     }
 
+    private void EmitStatementWhile(NodeStatementWhile statement)
+    {
+        var condition = EmitExpression(statement.Condition);
+        writer.WriteLine($"while ({condition})");
+        writer.WriteLine("{");
+        using (writer.Indent())
+        {
+            EmitStatement(statement.Block);
+        }
+        writer.WriteLine("}");
+    }
+
     private string EmitExpression(NodeExpression node)
     {
         return node switch

compiler/Compiler/Parser.cs

@@ -92,6 +92,13 @@ public sealed class Parser(List<Token> tokens)
             return new NodeStatementIf(TokensFrom(startIndex), condition, thenBlock, elseBlock);
         }
 
+        if (TryExpectKeyword(Keyword.While))
+        {
+            var condition = ParseExpression();
+            var thenBlock = ParseStatement();
+            return new NodeStatementWhile(TokensFrom(startIndex), condition, thenBlock);
+        }
+
         var target = ParseExpression();
 
         if (TryExpectSymbol(Symbol.OpenParen))
@@ -377,6 +384,12 @@ internal class NodeStatementIf(List<Token> tokens, NodeExpression condition, Nod
     public readonly NodeStatement? ElseBlock = elseBlock;
 }
 
+internal class NodeStatementWhile(List<Token> tokens, NodeExpression condition, NodeStatement block) : NodeStatement(tokens)
+{
+    public readonly NodeExpression Condition = condition;
+    public readonly NodeStatement Block = block;
+}
+
 public abstract class NodeExpression(List<Token> tokens) : Node(tokens);
 
 public sealed class NodeExpressionIntLiteral(List<Token> tokens, TokenIntLiteral value) : NodeExpression(tokens)

compiler/Compiler/Program.cs

@@ -7,11 +7,14 @@ const string contents = """
                             
                             if true {
                                 x = 49
-                            }
+                            } else {
-                            else {
                                 x = 3
                             }
                             
+                            while false {
+                                x = 6
+                            }
+                            
                             do_something("test")
                             return x
                         }

compiler/Compiler/Tokenizer.cs

@@ -280,6 +280,7 @@ public sealed class Tokenizer(string contents)
                         "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),
+                        "while" => new TokenKeyword(line, startColumn, column - startColumn, Keyword.While),
                         "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),
@@ -400,6 +401,7 @@ public enum Keyword
     Let,
     If,
     Else,
+    While,
     Return,
 }