Heads up! To view this whole video, sign in with your Courses account or enroll in your free 7-day trial. Sign In Enroll
Preview
Start a free Courses trial
to watch this video
Learn about the core concepts of the functional programming style.
[MUSIC]
0:00
Before we get into using
methods syntax with LINQ.
0:04
I wanna over a set of features in C# that
fit the style of functional programming.
0:07
Functional programming
languages focus on computations
0:14
as opposed to executing
a series of commands.
0:17
C# is an object oriented language.
0:19
However, many of the object oriented
languages out there have adopted elements
0:22
of functional programming and give us the
ability to program in a functional style.
0:27
LINQ queries are inherently functional
because as we write our queries,
0:32
we are expressing what we want,
and not how we want it.
0:36
If all this sounds a bit
confusing don't worry,
0:41
I'll show you some examples
that should help clear it up.
0:44
We'll only touch lightly on
functional programming for LINQ but
0:47
we'll cover it in more
detail in a future course.
0:50
There are some guidelines that functional
programming languages follow, and
0:54
it can be helpful to keep them
in mind when writing code.
0:58
The big one is that there
are no side effects.
1:01
When you run a function,
1:04
it should not modify anything
outside of the function scope.
1:05
For instance, if we have a function
that evaluates a collection that exists
1:09
outside the function, it shouldn't add or
remove anything from that collection.
1:13
Another concept is that functions
are first class citizens.
1:18
This means that functions
are treated like any other type and
1:22
can be passed around as objects.
1:26
We'll be going over delegates and other
function types in C# that let us do that.
1:28
We also wanna make sure that a function
has the smallest scope and performs
1:34
the least amount of work possible,
which is usually computational in nature.
1:38
We should be able to treat
it like a piece of data.
1:43
The function takes input and
gives us the result of the computation.
1:45
We could replace the function
call with its expected result and
1:50
everything would run the same.
1:54
This is a good practice, in general.
1:56
But it is definitely showcased when
applying functional programming concepts.
1:57
And last but
not least is the use of expressions.
2:02
For instance, instead of creating
a variable without a value and
2:06
then running some kind of
logic to assign its value.
2:09
You use an expression to assign
a value as you create it.
2:13
This concept goes very well with LINQ.
2:16
Applying these concepts in
your code has huge benefits.
2:19
Your code becomes more readable,
easier to maintain and easier to test.
2:23
However don't feel like you have to
use functional programming just for
2:28
the sake of it.
2:32
You can take these concepts and
2:33
apply them in your applications
if it's the right fit.
2:35
The goal is to help you
be a better programmer.
2:38
You don't have to relearn how to
program in a functional way but you can
2:41
take from these concepts and write code
that's cleaner and easier to maintain.
2:45
You need to sign up for Treehouse in order to download course files.
Sign up