An example of how to implement partially-applied generic factories with Functify so that you can create functions that create generic type factory methods with only some of the type parameters left open

gistfile1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace FunctifyBench
{
    using Functify;

    using LinFu.Delegates;

    public class SampleGenericType<T1, T2>
    {
        public void DoSomething(T1 first, T2 second)
        {
            Console.WriteLine(first);
            Console.WriteLine(second);
        }
    }


    public static class ArrayFunctorInputExtensions
    {
        public static Func<TResult> Narrow<T1, TResult>(this Func<T1[], TResult> builderFunc, T1 arg1)
        {
            return () => builderFunc(new[] { arg1 });
        }

        public static Func<TResult> Narrow<T1, TResult>(this Func<T1[], TResult> builderFunc, T1 arg1, T1 arg2)
        {
            return () => builderFunc(new[] { arg1, arg2 });
        }
        public static Func<TResult> Narrow<T1, TResult>(this Func<T1[], TResult> builderFunc, T1 arg1, T1 arg2, T1 arg3)
        {
            return () => builderFunc(new[] { arg1, arg2, arg3 });
        }
        public static Func<TResult> Narrow<T1, TResult>(this Func<T1[], TResult> builderFunc, T1 arg1, T1 arg2, T1 arg3, T1 arg4)
        {
            return () => builderFunc(new[] { arg1, arg2, arg3, arg4 });
        }

        public static Func<TResult> Narrow<T1, TResult>(this Func<T1[], TResult> builderFunc, T1 arg1, T1 arg2, T1 arg3, T1 arg4, T1 arg5)
        {
            return () => builderFunc(new[] { arg1, arg2, arg3, arg4, arg5 });
        }

        public static Func<TResult> Narrow<T1, TResult>(this Func<T1[], TResult> builderFunc, T1 arg1, T1 arg2, T1 arg3, T1 arg4, T1 arg5, T1 arg6)
        {
            return () => builderFunc(new[] { arg1, arg2, arg3, arg4, arg5, arg6 });
        }

        public static Func<TResult> Narrow<T1, TResult>(this Func<T1[], TResult> builderFunc, T1 arg1, T1 arg2, T1 arg3, T1 arg4, T1 arg5, T1 arg6, T1 arg7)
        {
            return () => builderFunc(new[] { arg1, arg2, arg3, arg4, arg5, arg6, arg7 });
        }
        public static Func<TResult> Narrow<T1, TResult>(this Func<T1[], TResult> builderFunc, T1 arg1, T1 arg2, T1 arg3, T1 arg4, T1 arg5, T1 arg6, T1 arg7, T1 arg8)
        {
            return () => builderFunc(new[] { arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8 });
        }
        public static Func<TResult> Narrow<T1, TResult>(this Func<T1[], TResult> builderFunc, T1 arg1, T1 arg2, T1 arg3, T1 arg4, T1 arg5, T1 arg6, T1 arg7, T1 arg8, T1 arg9)
        {
            return () => builderFunc(new[] { arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9 });
        }
        public static Func<TResult> Narrow<T1, TResult>(this Func<T1[], TResult> builderFunc, T1 arg1, T1 arg2, T1 arg3, T1 arg4, T1 arg5, T1 arg6, T1 arg7, T1 arg8, T1 arg9, T1 arg10)
        {
            return () => builderFunc(new[] { arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9, arg10 });
        }
        public static Func<TResult> Narrow<T1, TResult>(this Func<T1[], TResult> builderFunc, T1 arg1, T1 arg2, T1 arg3, T1 arg4, T1 arg5, T1 arg6, T1 arg7, T1 arg8, T1 arg9, T1 arg10, T1 arg11)
        {
            return () => builderFunc(new[] { arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8, arg9, arg10, arg11 });
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var typeDefinition = typeof(SampleGenericType<,>);
            Func<Type[], Type> makeGenericType = typeDefinition.MakeGenericType;

            Func<Type, Type, Type> createType = (type1, type2) => makeGenericType.Narrow(type1, type2)();
            
            // This is equivalent to creating a
            // SampleGenericType<T1,T2> with T1 being an open param, and T2 = typeof(int)
            var createPartial = createType.Partial<Func<Type, Type>>(Args.Open, typeof(int));

            // Create a SampleGenericType<string, int> type
            var firstType = createPartial(typeof(string));

            // Create a SampleGenericType<double, int> type
            var secondType = createPartial(typeof(double));

            return;
        }
    }
}