c# reader

gistfile1.cs

void Main()
{
    var environment = new Environment(30);
    var composed = DoSomeStuff();                    
    var extracted = composed.RunReader(environment);    
    Console.WriteLine(extracted);
}

public class Environment {
    public int Count {get; private set;}
    
    public void Log(string message) {
        Console.WriteLine("logging: " + message);
    }
    
    public Environment(int count) {
        Count = count;
    }
}

public Reader<Environment,Double> DoSomeStuff() {
    return  from i in Reader<Environment,int>.Wrap(e => 65)
            from d in DivideByCount(i)            
            select d;
}

public Reader<Environment,double> DivideByCount(int n) {    
    return Reader<Environment,double>.Wrap(e => { 
        e.Log(string.Format("Dividing {0} by {1}", n, e.Count));
        return Convert.ToDouble(n) / e.Count;
    });
}

public static class ReaderExt
{
    public static Reader<TEnv, T> SelectMany<TEnv, A, T, C>(this Reader<TEnv, A> reader, Func<A, Reader<TEnv, T>> bind, Func<A,T,C> select)
    {
        return new Reader<TEnv, T>(environment =>
        {
            var a = reader.EnvironmentToValue(environment);
            return bind(a).EnvironmentToValue(environment);
        });
    }
    
    public static T RunReader<TEnv, T>(this Reader<TEnv, T> reader, TEnv environment) {
        return reader.EnvironmentToValue(environment);
    }
}

public class Reader<TEnv, T> {
    public Func<TEnv,T> EnvironmentToValue;

    public Reader(Func<TEnv, T> environmentToValue) {
        EnvironmentToValue = environmentToValue;
    }
   
    public static Reader<TEnv,T> Wrap(Func<TEnv, T> environmentToValue) {
        return new Reader<TEnv, T>(environmentToValue);
   }
}