How Function Composition Can Make Your Code Better | Functional Programming

Function composition is a simple concept: you combine a few smaller functions to produce a more complicated function. An example is passing the results of a small function as an argument to a complex function. This is a common concept in functional programming, and I'll show you how it can make your code better.

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Chapters
0:00 What are we trying to do?
1:29 Defining the first function
2:48 Defining the second function
5:27 Implementing function composition
7:56 Another approach to function composition

[soverain]

The second approach is super clean, removes all the boilerplate that comes from static methods. I very much appreciate your videos about functional programming in C#, keep up the good work.

[adiazwise]

Great Milan, you explanation was very clear.

[krzysztofhandzlik]

Very nice and clean. That would be usefull in many cases, thanks.

[birukayalew]

Thank you Milan. I prefer the second one because it's more readable and we can passed many validations at once.

[Tamer_Ali]

Thanks Milan, you awesome
I hope you talk about Vertical Slice Architecture and compare it with Clean Architecture.

[andreibicu]

Hi Milan. Another great video.
I have one additional suggestion.
If the email is null or empty, we need to check on all predicates against it, otherwise we get null reference error.
Instead of repeating the check, I would advise to add the check in the Ensure method like this, and the call stays the same as you showed.
public static Result<T> Ensure<T>(
T value,
(Func<T, bool> Predicate, Error Error) hasValue,
params (Func<T, bool> Predicate, Error Error)[] functions)
{
if (!hasValue.Predicate(value))
{
return Failure<T>(hasValue.Error);
}
...
}
What do you think?

[angelldark]

I like both options, but would like more examples using class Rusults. I want more practice. Thanks

[mahmmoudkinawy]

Hello Milan, where to get resources to write a FP code such you.

[gardnerjens]

i like the idea of having an array of tuples one question, would it not be more functional had you use Aggregate instead of foreach? since you are creating a new type, then folding over the array of tuples you could then pass in the value t, to each function?

[darwish]

hello thank you its was useful, can i ask you how i can learn how i create my own extenision result ?
and Function Composition?

[EdsonViniciusSchmitt]

Hey there! On your thumbnail ... composition is spelled wrong ... to me it shows as "comopsition"

[antonmartyniuk]

I like the 2nd approach more. Looks much cleaner and has less code

[AmirHashemZadeh]

how could i get the ResultExtensions class?

[alberthalbert]

Thoughts on making videos showing how to build good WPF applications?

[able]

You are getting closer and closer to F# :D

[dusrdev]

About the second approach, it is rather unoptimized, firstly because the parameter is a params array object, in the function you can check the length of it and create an array of results to match the length, and use a for loop instead of the foreach, then pass the array to the combine method. This will entirely eliminate the List allocation, because you are already allocating a new array with the ToArray method which you could then remove. Or even more simple, without using the loop, run over the params object with a .Where method, and pass the Enumerable to the combine. For even more efficiency, you could modify the check to add an object only if an error occurred, and combine that with a .Where method.

[eloherbapol]

Nice video! But stop abusing the phrase "I'am going to" every 3 seconds :D