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compiler/NubLang/Optional.cs

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+using System.Diagnostics.CodeAnalysis;
+
+namespace NubLang;
+
+public static class Optional
+{
+    public static Optional<TValue> Empty<TValue>() => new();
+
+    /// <summary>
+    /// Alias for creating an Optional which allows for implicit types
+    /// </summary>
+    public static Optional<TValue> OfNullable<TValue>(TValue? value)
+    {
+        return value ?? Optional<TValue>.Empty();
+    }
+
+    /// <summary>
+    /// Converts a nullable type to an Optional
+    /// </summary>
+    public static Optional<TValue> ToOptional<TValue>(this TValue? value)
+    {
+        return OfNullable(value);
+    }
+}
+
+public readonly struct Optional<TValue>
+{
+    public static Optional<TValue> Empty() => new();
+
+    public static Optional<TValue> OfNullable(TValue? value)
+    {
+        return value ?? Empty();
+    }
+
+    public Optional()
+    {
+        Value = default;
+        HasValue = false;
+    }
+
+    public Optional(TValue value)
+    {
+        Value = value;
+        HasValue = true;
+    }
+
+    public TValue? Value { get; }
+
+    [MemberNotNullWhen(true, nameof(Value))]
+    public bool HasValue { get; }
+
+
+    [MemberNotNullWhen(true, nameof(Value))]
+    public bool TryGetValue([NotNullWhen(true)] out TValue? value)
+    {
+        if (HasValue)
+        {
+            value = Value;
+            return true;
+        }
+
+        value = default;
+        return false;
+    }
+
+    public TValue GetValue()
+    {
+        return Value ?? throw new InvalidOperationException("Value is not set");
+    }
+
+    public static implicit operator Optional<TValue>(TValue value) => new(value);
+
+    public TValue Or(TValue other)
+    {
+        if (HasValue)
+        {
+            return Value;
+        }
+
+        return other;
+    }
+}