Initial data commit

Task/Amb/C-sharp/amb-1.cs

@@ -0,0 +1,152 @@
+using System;
+using System.Collections.Generic;
+
+public class Amb : IDisposable
+{
+    List<IValueSet> streams = new List<IValueSet>();
+    List<IAssertOrAction> assertsOrActions = new List<IAssertOrAction>();
+    volatile bool stopped = false;
+
+    public IAmbValue<T> DefineValues<T>(params T[] values)
+    {
+        return DefineValueSet(values);
+    }
+
+    public IAmbValue<T> DefineValueSet<T>(IEnumerable<T> values)
+    {
+        ValueSet<T> stream = new ValueSet<T>();
+        stream.Enumerable = values;
+        streams.Add(stream);
+        return stream;
+    }
+
+    public Amb Assert(Func<bool> function)
+    {
+        assertsOrActions.Add(new AmbAssert()
+        {
+            Level = streams.Count,
+            IsValidFunction = function
+        });
+        return this;
+    }
+
+    public Amb Perform(Action action)
+    {
+        assertsOrActions.Add(new AmbAction()
+        {
+            Level = streams.Count,
+            Action = action
+        });
+        return this;
+    }
+
+    public void Stop()
+    {
+        stopped = true;
+    }
+
+    public void Dispose()
+    {
+        RunLevel(0, 0);
+        if (!stopped)
+        {
+            throw new AmbException();
+        }
+    }
+
+    void RunLevel(int level, int actionIndex)
+    {
+        while (actionIndex < assertsOrActions.Count && assertsOrActions[actionIndex].Level <= level)
+        {
+            if (!assertsOrActions[actionIndex].Invoke() || stopped)
+                return;
+            actionIndex++;
+        }
+        if (level < streams.Count)
+        {
+            using (IValueSetIterator iterator = streams[level].CreateIterator())
+            {
+                while (iterator.MoveNext())
+                {
+                    RunLevel(level + 1, actionIndex);
+                }
+            }
+        }
+    }
+
+    interface IValueSet
+    {
+        IValueSetIterator CreateIterator();
+    }
+
+    interface IValueSetIterator : IDisposable
+    {
+        bool MoveNext();
+    }
+
+    interface IAssertOrAction
+    {
+        int Level { get; }
+        bool Invoke();
+    }
+
+    class AmbAssert : IAssertOrAction
+    {
+        internal int Level;
+        internal Func<bool> IsValidFunction;
+
+        int IAssertOrAction.Level { get { return Level; } }
+
+        bool IAssertOrAction.Invoke()
+        {
+            return IsValidFunction();
+        }
+    }
+
+    class AmbAction : IAssertOrAction
+    {
+        internal int Level;
+        internal Action Action;
+
+        int IAssertOrAction.Level { get { return Level; } }
+
+        bool IAssertOrAction.Invoke()
+        {
+            Action(); return true;
+        }
+    }
+
+    class ValueSet<T> : IValueSet, IAmbValue<T>, IValueSetIterator
+    {
+        internal IEnumerable<T> Enumerable;
+        private IEnumerator<T> enumerator;
+
+        public T Value { get { return enumerator.Current; } }
+
+        public IValueSetIterator CreateIterator()
+        {
+            enumerator = Enumerable.GetEnumerator();
+            return this;
+        }
+
+        public bool MoveNext()
+        {
+            return enumerator.MoveNext();
+        }
+
+        public void Dispose()
+        {
+            enumerator.Dispose();
+        }
+    }
+}
+
+public interface IAmbValue<T>
+{
+    T Value { get; }
+}
+
+public class AmbException : Exception
+{
+    public AmbException() : base("AMB is angry") { }
+}

Task/Amb/C-sharp/amb-2.cs

@@ -0,0 +1,30 @@
+    // original problem
+    using (Amb amb = new Amb())
+    {
+        var set1 = amb.DefineValues("the", "that", "a");
+        var set2 = amb.DefineValues("frog", "elephant", "thing");
+        var set3 = amb.DefineValues("walked", "treaded", "grows");
+        var set4 = amb.DefineValues("slowly", "quickly");
+
+        amb.Assert(() => IsJoinable(set1.Value, set2.Value));
+        amb.Assert(() => IsJoinable(set2.Value, set3.Value));
+        amb.Assert(() => IsJoinable(set3.Value, set4.Value));
+
+        amb.Perform(() =>
+            {
+                System.Console.WriteLine("{0} {1} {2} {3}", set1.Value, set2.Value, set3.Value, set4.Value);
+                amb.Stop();
+            });
+    }
+    // problem from http://www.randomhacks.net/articles/2005/10/11/amb-operator
+    using (Amb amb = new Amb())
+    {
+        IAmbValue<int> x = amb.DefineValues(1, 2, 3);
+        IAmbValue<int> y = amb.DefineValues(4, 5, 6);
+        amb.Assert(() => x.Value * y.Value == 8);
+        amb.Perform(() =>
+            {
+                System.Console.WriteLine("{0} {1}", x.Value, y.Value);
+                amb.Stop();
+            });
+    }

Task/Amb/C-sharp/amb-3.cs

@@ -0,0 +1,73 @@
+using System;
+using System.Collections.Generic;
+
+namespace Amb {
+    public interface IValue<T> {
+        T Value { get; }
+        string ToString();
+    }
+
+    public sealed class Amb {
+        public IValue<T> Choose<T>(params T[] choices) {
+            var array = new ChoiceArray<T> { Values = choices };
+            _choices.Add(array);
+            return array;
+        }
+
+        public void Require(Func<bool> predicate) =>
+            _constraints.Add(new Constraint { Predicate = predicate, AppliesForItems = _choices.Count });
+
+        public bool Disambiguate() => Disambiguate(0, 0);
+
+        interface IChoices {
+            int Length { get; }
+            int Index { get; set; }
+        }
+
+        interface IConstraint {
+            int AppliesForItems { get; }
+            bool Invoke();
+        }
+
+        readonly List<IChoices> _choices = new();
+        readonly List<IConstraint> _constraints = new();
+
+        bool Disambiguate(int choicesTracked, int constraintIdx) {
+            while (constraintIdx < _constraints.Count && _constraints[constraintIdx].AppliesForItems <= choicesTracked) {
+                if (!_constraints[constraintIdx].Invoke())
+                    return false;
+                constraintIdx++;
+            }
+
+            if (choicesTracked == _choices.Count)
+                return true;
+
+            for (var i = 0; i < _choices[choicesTracked].Length; i++) {
+                _choices[choicesTracked].Index = i;
+                if (Disambiguate(choicesTracked + 1, constraintIdx))
+                    return true;
+            }
+            return false;
+        }
+
+        class Constraint : IConstraint {
+            internal Func<bool> Predicate;
+
+            public int AppliesForItems { get; set; }
+
+            public bool Invoke() => Predicate?.Invoke() ?? default;
+        }
+
+        class ChoiceArray<T> : IChoices, IValue<T> {
+            internal T[] Values;
+
+            public int Index { get; set; }
+
+            public T Value => Values[Index];
+
+            public int Length => Values.Length;
+
+            public override string ToString() => Value.ToString();
+        }
+    }
+}

Task/Amb/C-sharp/amb-4.cs

@@ -0,0 +1,32 @@
+using System.Linq;
+using static System.Console;
+
+namespace Amb {
+    class Program {
+        static void Main(string[] args) {
+
+            var amb = new Amb();
+
+            var set1 = amb.Choose("the", "that", "a");
+            var set2 = amb.Choose("frog", "elephant", "thing");
+            amb.Require(() => set1.Value.Last() == set2.Value[0]);
+            var set3 = amb.Choose("walked", "treaded", "grows");
+            amb.Require(() => set2.Value.Last() == set3.Value[0]);
+            var set4 = amb.Choose("slowly", "quickly");
+            amb.Require(() => set3.Value.Last() == set4.Value[0]);
+
+            WriteLine(amb.Disambiguate()? $"{set1} {set2} {set3} {set4}" : "Amb failed");
+            Read();
+
+            // problem from http://www.randomhacks.net/articles/2005/10/11/amb-operator
+            amb = new Amb();
+
+            var x = amb.Choose(1, 2, 3);
+            var y = amb.Choose(4, 5, 6);
+            amb.Require(() => x.Value * y.Value == 8);
+
+            WriteLine(amb.Disambiguate() ? $"{x} * {y} = 8" : "Amb failed");
+            Read();
+        }
+    }
+}

Task/Amb/C-sharp/amb-5.cs

@@ -0,0 +1,22 @@
+using static System.Console;
+using System.Linq;
+
+string[] w1 = { "the", "that", "a" };
+string[] w2 = { "frog", "elephant", "thing" };
+string[] w3 = { "walked", "treaded", "grows" };
+string[] w4 = { "slowly", "quickly" };
+
+var result = from a in w1
+             join b in w2 on a?.LastOrDefault() equals b?.FirstOrDefault()
+             join c in w3 on b?.LastOrDefault() equals c?.FirstOrDefault()
+             join d in w4 on c?.LastOrDefault() equals d?.FirstOrDefault()
+             select new [] {a, b, c, d};
+WriteLine(string.Join(" ", result.SelectMany(x => x)));
+
+double[] x = { 1, 2, 3 };
+double[] y = { 7, 6, 4, 5 };
+
+var result2 = from a in x
+              join b in y on a equals 8 / b
+              select new[] { a, b };
+WriteLine(string.Join(" ", result2.SelectMany(x => x)));