ErsatzTV/ErsatzTV.Application/Validators/NumericValidation.cs

using System;
using System.Linq.Expressions;
using ErsatzTV.Core;
using LanguageExt;
using static LanguageExt.Prelude;

namespace ErsatzTV
{
    public static partial class Validators
    {
        public static Func<Expression<Func<T, int>>, Validation<BaseError, int>>
            AtLeast<T>(this T input, int minimum) =>
            value => Optional(value)
                .Map(i => i.Compile()(input))
                .Where(i => i >= minimum)
                .ToValidation<BaseError>(
                    $"[{GetMemberName(value)}] must be greater or equal to {minimum}");
    }
}