feat: add NotEqualsFunction for inequality comparison across multiple types

Author: pksorensen

src/Compo/Functions/Logical/NotEqualsFunction.cs

@@ -0,0 +1,40 @@
+namespace Compo.Functions.Logical;
+
+/// <summary>
+/// Inequality comparison.
+/// Returns true if values are not equal.
+/// Convenience function equivalent to not(equals(a, b)).
+/// </summary>
+[FunctionRegistration("neq")]
+public class NotEqualsFunction :
+    IFunction<string, string, bool>,
+    IFunction<int, int, bool>,
+    IFunction<double, double, bool>,
+    IFunction<decimal, decimal, bool>,
+    IFunction<bool, bool, bool>
+{
+    public bool Execute(string a, string b)
+    {
+        return !string.Equals(a, b, StringComparison.Ordinal);
+    }
+
+    public bool Execute(int a, int b)
+    {
+        return a != b;
+    }
+
+    public bool Execute(double a, double b)
+    {
+        return System.Math.Abs(a - b) >= double.Epsilon;
+    }
+
+    public bool Execute(decimal a, decimal b)
+    {
+        return a != b;
+    }
+
+    public bool Execute(bool a, bool b)
+    {
+        return a != b;
+    }
+}