Implemented loops and empty string constants,

Starship/Rockstar.Engine/Expressions/CommonVariable.cs

@@ -0,0 +1,6 @@
+namespace Rockstar.Engine.Expressions;
+
+public class CommonVariable(string name, Source source) : Variable(name, source) {
+	public CommonVariable(string name) : this(name, Source.None) { }
+	public override string Key => NormalizedName.ToLowerInvariant();
+}

Starship/Rockstar.Engine/Expressions/Pronoun.cs

@@ -0,0 +1,12 @@
+using System.Text;
+
+namespace Rockstar.Engine.Expressions;
+
+public class Pronoun(string name, Source source) : Variable(name, source) {
+	public Pronoun() : this(String.Empty) { }
+	public Pronoun(string name) : this(name, Source.None) { }
+	public override string Key => Name.ToLowerInvariant();
+	public override void Print(StringBuilder sb, int depth) {
+		sb.Indent(depth).AppendLine($"pronoun: {Name}");
+	}
+}

Starship/Rockstar.Engine/Expressions/ProperVariable.cs

@@ -0,0 +1,6 @@
+namespace Rockstar.Engine.Expressions;
+
+public class ProperVariable(string name, Source source) : Variable(name, source) {
+	public ProperVariable(string name) : this(name, Source.None) { }
+	public override string Key => NormalizedName.ToUpperInvariant();
+}

Starship/Rockstar.Engine/Expressions/SimpleVariable.cs

@@ -0,0 +1,6 @@
+namespace Rockstar.Engine.Expressions;
+
+public class SimpleVariable(string name, Source source) : Variable(name, source) {
+	public SimpleVariable(string name) : this(name, Source.None) { }
+	public override string Key => Name.ToLowerInvariant();
+}

Starship/Rockstar.Engine/Expressions/Variable.cs

@@ -16,28 +16,4 @@ protected string NormalizedName
 		=> String.Join("_", whitespace.Split(Name));
 
 	public abstract string Key { get; }
-}
-
-public class Pronoun(string name, Source source) : Variable(name, source) {
-	public Pronoun() : this(String.Empty) { }
-	public Pronoun(string name) : this(name, Source.None) { }
-	public override string Key => Name.ToLowerInvariant();
-	public override void Print(StringBuilder sb, int depth) {
-		sb.Indent(depth).AppendLine($"pronoun: {Name}");
-	}
-}
-
-public class SimpleVariable(string name, Source source) : Variable(name, source) {
-	public SimpleVariable(string name) : this(name, Source.None) { }
-	public override string Key => Name.ToLowerInvariant();
-}
-
-public class ProperVariable(string name, Source source) : Variable(name, source) {
-	public ProperVariable(string name) : this(name, Source.None) { }
-	public override string Key => NormalizedName.ToUpperInvariant();
-}
-
-public class CommonVariable(string name, Source source) : Variable(name, source) {
-	public CommonVariable(string name) : this(name, Source.None) { }
-	public override string Key => NormalizedName.ToLowerInvariant();
-}
+}

Starship/Rockstar.Engine/Interpreter.cs

@@ -4,11 +4,6 @@
 
 namespace Rockstar.Engine;
 
-public class Result {
-	public static readonly Result Ok = new();
-	public static readonly Result Unknown = new();
-}
-
 public class Interpreter(RockstarEnvironment env) {
 
 	public Result Exec(Block block) {
@@ -23,9 +18,20 @@ public Result Exec(Block block) {
 		Conditional cond => Conditional(cond),
 		Increment inc => Increment(inc),
 		Decrement dec => Decrement(dec),
+		Loop loop => Loop(loop),
 		_ => throw new($"I don't know how to execute {statement.GetType().Name} statements")
 	};
 
+	private Result Loop(Loop loop) {
+		var result = Result.Unknown;
+		var condition = Eval(loop.Condition);
+		while (condition.Truthy == loop.CompareTo) {
+			result = Exec(loop.Body);
+			condition = Eval(loop.Condition);
+		}
+		return result;
+	}
+
 	private Result Increment(Increment inc) {
 		return Eval(inc.Variable) switch {
 			Number n => Assign(inc.Variable, new Number(n.Value + inc.Multiple)),

Starship/Rockstar.Engine/PegasusParserExtensions.cs

@@ -0,0 +1,12 @@
+using System.Text.RegularExpressions;
+using Pegasus.Common;
+
+namespace Rockstar.Engine;
+
+public static class PegasusParserExtensions {
+	public static Source Source(this Cursor cursor, string lexeme = "")
+		=> new(cursor.Line, cursor.Column, lexeme);
+
+	public static string Error(this Cursor cursor, string unexpected)
+		=> "Unexpected '" + Regex.Escape(unexpected) + "' at line " + cursor.Line + ", col " + (cursor.Column - 1);
+}

Starship/Rockstar.Engine/Result.cs

@@ -0,0 +1,6 @@
+namespace Rockstar.Engine;
+
+public class Result {
+	public static readonly Result Ok = new();
+	public static readonly Result Unknown = new();
+}

Starship/Rockstar.Engine/Source.cs

@@ -1,6 +1,3 @@
-using Pegasus.Common;
-using System.Text.RegularExpressions;
-
 namespace Rockstar.Engine;
 
 public class Source(int line, int column, string lexeme = "") {
@@ -9,12 +6,4 @@ public class Source(int line, int column, string lexeme = "") {
 		$"(line {line}, column {column - lexeme.Length} [{lexeme}])";
 
 	public static readonly Source None = new(0, 0, "");
-}
-
-public static class PegasusParserExtensions {
-	public static Source Source(this Cursor cursor, string lexeme = "")
-		=> new(cursor.Line, cursor.Column, lexeme);
-
-	public static string Error(this Cursor cursor, string unexpected)
-		=> "Unexpected '" + Regex.Escape(unexpected) + "' at line " + cursor.Line + ", col " + (cursor.Column - 1);
-}
+}

Starship/Rockstar.Engine/Statements/Conditional.cs

@@ -3,25 +3,6 @@
 
 namespace Rockstar.Engine.Statements;
 
-public class Increment(Variable v, int multiple, Source source) : Statement(source) {
-	public Variable Variable => v;
-	public int Multiple => multiple;
-	public override void Print(StringBuilder sb, int depth = 0) {
-		sb.Indent(depth).AppendLine($"increment x {multiple}");
-		v.Print(sb, depth + 1);
-	}
-}
-
-public class Decrement(Variable v, int multiple, Source source) : Statement(source) {
-	public Variable Variable => v;
-	public int Multiple => multiple;
-	public override void Print(StringBuilder sb, int depth = 0) {
-		sb.Indent(depth).AppendLine($"decrement x {multiple}");
-		v.Print(sb, depth + 1);
-	}
-}
-
-
 public class Conditional(Expression condition, Block consequent, Source source)
 	: Statement(source) {
 	public Expression Condition => condition;

Starship/Rockstar.Engine/Statements/Decrement.cs

@@ -0,0 +1,13 @@
+using System.Text;
+using Rockstar.Engine.Expressions;
+
+namespace Rockstar.Engine.Statements;
+
+public class Decrement(Variable v, int multiple, Source source) : Statement(source) {
+	public Variable Variable => v;
+	public int Multiple => multiple;
+	public override void Print(StringBuilder sb, int depth = 0) {
+		sb.Indent(depth).AppendLine($"decrement x {multiple}");
+		v.Print(sb, depth + 1);
+	}
+}

Starship/Rockstar.Engine/Statements/Increment.cs

@@ -0,0 +1,13 @@
+using System.Text;
+using Rockstar.Engine.Expressions;
+
+namespace Rockstar.Engine.Statements;
+
+public class Increment(Variable v, int multiple, Source source) : Statement(source) {
+	public Variable Variable => v;
+	public int Multiple => multiple;
+	public override void Print(StringBuilder sb, int depth = 0) {
+		sb.Indent(depth).AppendLine($"increment x {multiple}");
+		v.Print(sb, depth + 1);
+	}
+}

Starship/Rockstar.Engine/Statements/Loop.cs

@@ -0,0 +1,20 @@
+using System.Text;
+using Rockstar.Engine.Expressions;
+using Rockstar.Engine.Values;
+
+namespace Rockstar.Engine.Statements;
+
+public abstract class Loop(Expression condition, bool compareTo, Block body, Source source)
+	: Statement(source) {
+	public bool CompareTo => compareTo;
+	public Expression Condition => condition;
+	public Block Body => body;
+	protected abstract string LoopType { get; }
+	public override void Print(StringBuilder sb, int depth = 0) {
+		sb.Indent(depth).AppendLine($"{LoopType}:");
+		sb.Indent(depth + 1).AppendLine("test:");
+		condition.Print(sb, depth + 2);
+		sb.Indent(depth + 1).AppendLine("then:");
+		body.Print(sb, depth + 2);
+	}
+}

Starship/Rockstar.Engine/Statements/UntilLoop.cs

@@ -0,0 +1,8 @@
+using Rockstar.Engine.Expressions;
+
+namespace Rockstar.Engine.Statements;
+
+public class UntilLoop(Expression condition, Block body, Source source)
+	: Loop(condition, false, body, source) {
+	protected override string LoopType => "until";
+}

Starship/Rockstar.Engine/Statements/WhileLoop.cs

@@ -0,0 +1,8 @@
+using Rockstar.Engine.Expressions;
+
+namespace Rockstar.Engine.Statements;
+
+public class WhileLoop(Expression condition, Block body, Source source)
+	: Loop(condition, true, body, source) {
+	protected override string LoopType => "while";
+}

Starship/Rockstar.Engine/Values/IHaveANumber.cs

@@ -0,0 +1,5 @@
+namespace Rockstar.Engine.Values;
+
+public interface IHaveANumber {
+	decimal NumericValue { get; }
+}

Starship/Rockstar.Engine/Values/Number.cs

@@ -2,10 +2,6 @@
 using System.Text;
 namespace Rockstar.Engine.Values;
 
-public interface IHaveANumber {
-	decimal NumericValue { get; }
-}
-
 public class Number(decimal value, Source source)
 	: Value(source), IHaveANumber {
 

Starship/Rockstar.Engine/Values/Strïng.cs

@@ -15,7 +15,16 @@ public override void Print(StringBuilder sb, int depth)
 	public static readonly Strïng False = new("false");
 	public static readonly Strïng Null = new("null");
 	public static readonly Strïng Mysterious = new("mysterious");
+	public static readonly Strïng Empty = new(String.Empty);
+
+	private Strïng(IEnumerable<string> strings)
+		: this(String.Join("", strings)) { }
 
 	public Value Concat(Value that)
 		=> new Strïng(this.Value + that.ToStrïng().Value);
+
+	public Value Repeat(IHaveANumber n)
+		=> new Strïng(Enumerable
+			.Range(0, (int) n.NumericValue)
+			.Select(_ => this.Value));
 }

Starship/Rockstar.Engine/Values/Value.cs

@@ -14,8 +14,14 @@ public abstract class Value(Source source)
 	public Value Or(Value that) => this.Truthy ? this : that;
 
 	public Value Plus(Value that) => (this, that) switch {
-		(Number a, Number b) => new Number(a.Value + b.Value),
 		(Strïng a, _) => a.Concat(that),
+		(_, Strïng b) => this.ToStrïng().Concat(b),
+		(IHaveANumber a, IHaveANumber b)
+			=> new Number(a.NumericValue + b.NumericValue),
+		(IHaveANumber a, _)
+			=> Decimal.TryParse(that.ToStrïng().Value, out var d)
+				? new Number(a.NumericValue + d)
+					: throw Boom(nameof(Plus), this, that),
 		_ => throw Boom(nameof(Plus), this, that)
 	};
 
@@ -43,7 +49,8 @@ public override void Print(StringBuilder sb, int depth)
 	public Value Times(Value that) => (this, that) switch {
 		(IHaveANumber a, IHaveANumber b)
 			=> new Number(a.NumericValue * b.NumericValue),
-		_ => throw new NotImplementedException()
+		(Strïng s, IHaveANumber n) => s.Repeat(n),
+		_ => Mysterious.Instance
 	};
 
 	public Value Divide(Value that) => (this, that) switch {

Starship/Rockstar.Engine/rockstar.peg

@@ -40,7 +40,8 @@ EOF	= !.
 		#error{ $"Unexpected '{Regex.Escape(unexpected)}' at line {state.Line}, col {state.Column - 1}" }
 
 statement <Statement>
-	= alternate
+	= loop
+	/ alternate
 	/ output_stmt
 	/ assign_stmt
 	/ increment
@@ -58,15 +59,21 @@ decrement <Decrement>
 		{ new Decrement(v, t.Count, state.Source()) }
 
 alternate <Conditional>
-	= c:conditional (_ / EOS) 'else' a:bonglit
+	= c:conditional (_ / EOS) 'else' a:body
 		{ c.Else(a) }
 	/ c:conditional { c }
 
 conditional <Conditional>
-	= 'if' _ e:expression a:bonglit
+	= 'if' _ e:expression a:body
 		{ new Conditional(e, a, state.Source()) }
 
-bonglit <Block>
+loop <Loop>
+	= 'while' _ e:expression b:body
+		{ new WhileLoop(e, b, state.Source()) }
+	/ 'until' _ e:expression b:body
+		{ new UntilLoop(e, b, state.Source()) }
+
+body <Block>
 	= EOS b:block
 		{ b }
 	/ _ s:statement
@@ -137,7 +144,7 @@ common_prefix
 	= ('an' / 'a' / 'the' / 'my' / 'your' / 'our') !letter
 
 simple_variable
-	= !keyword ("" letter+)
+	= !keyword ("" letter (letter / [0-9])*)
 
 letter
 	= uppercase_letter / lowercase_letter
@@ -248,6 +255,10 @@ constant <Expression>
 	/ f:false { new Booleän(false, state.Source(f)) }
 	/ n:null { new Null(state.Source(n)) }
 	/ m:'mysterious' { Mysterious.Instance }
+	/ e:empty { Strïng.Empty }
+
+empty
+	= ('empty'i / 'silent'i / 'silence'i)
 
 true
 	= ("true" / "yes" / "ok" / "right") !letter